Patent Publication Number: US-2023165124-A1

Title: Method for patterning a coating on a surface and device including a patterned coating

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/608,794, filed Oct. 25, 2019, which application is a National Stage Entry of International Application No. PCT/1132018/052881, filed Apr. 26, 2018, which application claims the benefit of and priority to U.S. Provisional Application No. 62/490,564, filed Apr. 26, 2017, US Provisional Application No. 62/521,499, filed Jun. 18, 2017, and U.S. Provisional Application No. 62/573,028, filed Oct. 16, 2017, the contents of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The following generally relates to a method for depositing an electrically conductive material on a surface. Specifically, the method relates to selective deposition of the electrically conductive material on a surface for forming an electrically conductive structure of a device. 
     BACKGROUND 
     Organic light emitting diodes (OLEDs) typically include several layers of organic materials interposed between conductive thin film electrodes, with at least one of the organic layers being an electroluminescent layer. When a voltage is applied to electrodes, holes and electrons are injected from an anode and a cathode, respectively. The holes and electrons injected by the electrodes migrate through the organic layers to reach the electroluminescent layer. When a hole and an electron are in close proximity, they are attracted to each other due to a Coulomb force. The hole and electron may then combine to form a bound state referred to as an exciton. An exciton may decay through a radiative recombination process, in which a photon is released. Alternatively, an exciton may decay through a non-radiative recombination process, in which no photon is released. It is noted that, as used herein, internal quantum efficiency (IQE) will be understood to be a proportion of all electron-hole pairs generated in a device which decay through a radiative recombination process. 
     A radiative recombination process can occur as a fluorescence or phosphorescence process, depending on a spin state of an electron-hole pair (namely, an exciton). Specifically, the exciton formed by the electron-hole pair may be characterized as having a singlet or triplet spin state. Generally, radiative decay of a singlet exciton results in fluorescence, whereas radiative decay of a triplet exciton results in phosphorescence. 
     More recently, other light emission mechanisms for OLEDs have been proposed and investigated, including thermally activated delayed fluorescence (TADF). Briefly, TADF emission occurs through a conversion of triplet excitons into singlet excitons via a reverse inter system crossing process with the aid of thermal energy, followed by radiative decay of the singlet excitons. 
     An external quantum efficiency (EQE) of an OLED device may refer to a ratio of charge carriers provided to the OLED device relative to a number of photons emitted by the device. For example, an EQE of 100% indicates that one photon is emitted for each electron that is injected into the device. As will be appreciated, an EQE of a device is generally substantially lower than an IQE of the device. The difference between the EQE and the IQE can generally be attributed to a number of factors such as absorption and reflection of light caused by various components of the device. 
     An OLED device can typically be classified as being either a “bottom-emission” or “top-emission” device, depending on a relative direction in which light is emitted from the device. In a bottom-emission device, light generated as a result of a radiative recombination process is emitted in a direction towards a base substrate of the device, whereas, in a top-emission device, light is emitted in a direction away from the base substrate. Accordingly, an electrode that is proximal to the base substrate is generally made to be light transmissive (e.g., substantially transparent or semi-transparent) in a bottom-emission device, whereas, in a top-emission device, an electrode that is distal to the base substrate is generally made to be light transmissive in order to reduce attenuation of light. Depending on the specific device structure, either an anode or a cathode may act as a transmissive electrode in top-emission and bottom-emission devices. 
     An OLED device also may be a double-sided emission device, which is configured to emit light in both directions relative to a base substrate. For example, a double-sided emission device may include a transmissive anode and a transmissive cathode, such that light from each pixel is emitted in both directions. In another example, a double-sided emission display device may include a first set of pixels configured to emit light in one direction, and a second set of pixels configured to emit light in the other direction, such that a single electrode from each pixel is transmissive. 
     In addition to the above device configurations, a transparent or semi-transparent OLED device also can be implemented, in which the device includes a transparent portion which allows external light to be transmitted through the device. For example, in a transparent OLED display device, a transparent portion may be provided in a non-emissive region between each neighboring pixels. In another example, a transparent OLED lighting panel may be formed by providing a plurality of transparent regions between emissive regions of the panel. Transparent or semi-transparent OLED devices may be bottom-emission, top-emission, or double-sided emission devices. 
     While either a cathode or an anode can be selected as a transmissive electrode, a typical top-emission device includes a light transmissive cathode. Materials which are typically used to form the transmissive cathode include transparent conducting oxides (TCOs), such as indium tin oxide (ITO) and zinc oxide (ZnO), as well as thin films, such as those formed by depositing a thin layer of silver (Ag), aluminum (Al), or various metallic alloys such as magnesium silver (Mg:Ag) alloy and ytterbium silver (Yb:Ag) alloy with compositions ranging from about 1:9 to about 9:1 by volume. A multi-layered cathode including two or more layers of TCOs and/or thin metal films also can be used. 
     Particularly in the case of thin films, a relatively thin layer thickness of up to about a few tens of nanometers contributes to enhanced transparency and favorable optical properties (e.g., reduced microcavity effects) for use in OLEDs. However, a reduction in the thickness of a transmissive electrode is accompanied by an increase in its sheet resistance. An electrode with a high sheet resistance is generally undesirable for use in OLEDs, since it creates a large current-resistance (IR) drop when a device is in use, which is detrimental to the performance and efficiency of OLEDs. The IR drop can be compensated to some extent by increasing a power supply level; however, when the power supply level is increased for one pixel, voltages supplied to other components are also increased to maintain proper operation of the device, and thus is unfavorable. 
     In order to reduce power supply specifications for top-emission OLED devices, solutions have been proposed to form busbar structures or auxiliary electrodes on the devices. For example, such an auxiliary electrode may be formed by depositing a conductive coating in electrical communication with a transmissive electrode of an OLED device. Such an auxiliary electrode may allow current to be carried more effectively to various regions of the device by lowering a sheet resistance and an associated IR drop of the transmissive electrode. 
     Since an auxiliary electrode is typically provided on top of an OLED stack including an anode, one or more organic layers, and a cathode, patterning of the auxiliary electrode is traditionally achieved using a shadow mask with mask apertures through which a conductive coating is selectively deposited, for example by a physical vapor deposition (PVD) process. However, since masks are typically metal masks, they have a tendency to warp during a high-temperature deposition process, thereby distorting mask apertures and a resulting deposition pattern. Furthermore, a mask is typically degraded through successive depositions, as a conductive coating adheres to the mask and obfuscates features of the mask. Consequently, such a mask should either be cleaned using time-consuming and expensive processes or should be disposed once the mask is deemed to be ineffective at producing the desired pattern, thereby rendering such process highly costly and complex. Accordingly, a shadow mask process may not be commercially feasible for mass production of OLED devices. Moreover, an aspect ratio of features which can be produced using the shadow mask process is typically constrained due to shadowing effects and a mechanical (e.g., tensile) strength of the metal mask, since large metal masks are typically stretched during a shadow mask deposition process. 
     Another challenge of patterning a conductive coating onto a surface through a shadow mask is that certain, but not all, patterns can be achieved using a single mask. As each portion of the mask is physically supported, not all patterns are possible in a single processing stage. For example, where a pattern specifies an isolated feature, a single mask processing stage typically cannot be used to achieve the desired pattern. In addition, masks which are used to produce repeating structures (e.g., busbar structures or auxiliary electrodes) spread across an entire device surface include a large number of perforations or apertures formed on the masks. However, forming a large number of apertures on a mask can compromise the structural integrity of the mask, thus leading to significant warping or deformation of the mask during processing, which can distort a pattern of deposited structures. 
     In addition to the above, when a common electrode having a substantially uniform thickness is provided as the top-emission cathode in an OLED display device, the optical performance of the device cannot readily be fine tuned according to the emission spectrum associated each subpixel. In a typical OLED display device, red, green, and blue subpixels are provided to form the pixels of the display device. The top-emission electrode used in such OLED display device is typically a common electrode coating a plurality of pixels. For example, such common electrode may be a relatively thin conductive layer having a substantially uniform thickness across the device. While efforts have been made to tune the optical microcavity effects associated with each subpixel color by varying the thickness of organic layers disposed within different subpixels, such approach may not provide sufficient degree of tuning of the optical microcavity effects in at least some cases. In addition, such approach may be difficult to implement in an OLED display production environment. 
     SUMMARY OF THE INVENTION 
     According to some embodiments, a device (e.g., an opto-electronic device) includes: (1) a substrate including a first region and a second region; and (2) a conductive coating covering the second region of the substrate. The first region of the substrate is exposed from the conductive coating, and an edge the conductive coating adjacent to the first region of the substrate has a contact angle that is greater than about 20 degrees. 
     According to some embodiments, a device (e.g., an opto-electronic device) includes: (1) a substrate; (2) a nucleation inhibiting coating covering a first region of the substrate; and (3) a conductive coating covering a laterally adjacent, second region of the substrate. A surface of the nucleation inhibiting coating is characterized, with respect to a material of the conductive coating, as having a desorption activation energy greater than or equal to a diffusion activation energy of the surface, and less than or equal to about 2.5 times the diffusion activation energy of the surface. 
     According to some embodiments, a manufacturing method of a device (e.g., an opto-electronic device) includes: (1) providing a substrate and a nucleation inhibiting coating covering a first region of the substrate; and (2) depositing a conductive coating covering a second region of the substrate. The conductive coating includes magnesium, and a surface of the nucleation inhibiting coating is characterized, with respect to magnesium, as having a relationship between a desorption activation energy and a diffusion activation energy in which the desorption activation energy is greater than or equal to the diffusion activation energy, and less than or equal to about 2.5 times the diffusion activation energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some embodiments will now be described by way of example with reference to the appended drawings wherein: 
         FIG.  1    is a schematic diagram illustrating a shadow mask deposition of a nucleation inhibiting coating according to one embodiment; 
         FIG.  2 A ,  FIG.  2 B , and  FIG.  2 C  are schematic diagrams illustrating a micro-contact transfer printing process of a nucleation inhibiting coating according to one embodiment; 
         FIG.  3    is a schematic diagram illustrating the deposition of a conductive coating on a patterned surface according to one embodiment; 
         FIG.  4    is a diagram illustrating a device produced according to one embodiment of a process; 
         FIG.  5 A ,  FIGS.  5 B, and  5 C  are schematic diagrams illustrating a process for selectively depositing a conductive coating according to one embodiment; 
         FIG.  5 D ,  FIGS.  5 E, and  5 F  are schematic diagrams illustrating a process for selectively depositing a conductive coating according to another embodiment; 
         FIG.  6    is a diagram illustrating an electroluminescent device according to one embodiment; 
         FIG.  7    is a flow diagram showing process stages according to one embodiment; 
         FIG.  8 A  is a top view illustrating an open mask according to one example; 
         FIG.  8 B  is a top view illustrating an open mask according to another example; 
         FIG.  8 C  is a top view illustrating an open mask according to yet another example; 
         FIG.  8 D  is a top view illustrating an open mask according to yet another example; 
         FIG.  9    is a top view of an OLED device according to one embodiment; 
         FIG.  10    is a cross-sectional view of the OLED device of  FIG.  9   ; 
         FIG.  11    is a cross-sectional view of an OLED device according to another embodiment; 
         FIG.  12 A  is a schematic diagram illustrating a top view of a passive matrix OLED device according to one embodiment; 
         FIG.  12 B  is a schematic cross-sectional view of the passive matrix OLED device of  FIG.  12 A ; 
         FIG.  12 C  is a schematic cross-sectional view of the passive matrix OLED device of  FIG.  12 B  after encapsulation; 
         FIG.  12 D  is a schematic cross-sectional view of a comparative passive matrix OLED device; 
         FIG.  13 A ,  FIG.  13 B ,  FIGS.  13 C, and  13 D  illustrate portions of auxiliary electrodes according to various embodiments; 
         FIG.  14    illustrate an auxiliary electrode pattern formed on an OLED device according to one embodiment; 
         FIG.  15    illustrate a portion of a device with a pixel arrangement according to one embodiment; 
         FIG.  16    is a cross-sectional diagram taken along line A-A of the device according to  FIG.  15   ; 
         FIG.  17    is a cross-sectional diagram taken along line B-B of the device according to  FIG.  15   ; 
         FIG.  18    is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to one embodiment; 
         FIG.  19    is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to another embodiment; 
         FIG.  20 A  is a diagram illustrating a cross-sectional profile around an interface of a conductive coating, a nucleation inhibiting coating, and a nucleation promoting coating according to one embodiment; 
         FIG.  20 B  is a diagram illustrating a cross-sectional profile around an interface of a conductive coating, a nucleation inhibiting coating, and a nucleation promoting coating according to another embodiment; 
         FIG.  21    is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to yet another embodiment; 
         FIG.  22 A  is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to yet another embodiment; 
         FIG.  22 B  is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to yet another embodiment; 
         FIG.  22 C  is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to yet another embodiment; 
         FIG.  22 D  is a diagram illustrating a cross-sectional profile around an interface of a conductive coating and a nucleation inhibiting coating according to yet another embodiment; 
         FIG.  23 A  and  FIG.  23 B  illustrate a process for removing a nucleation inhibiting coating following deposition of a conductive coating according to one embodiment; 
         FIG.  24    is a diagram illustrating a cross-sectional profile of an active matrix OLED device according to one embodiment; 
         FIG.  25    is a diagram illustrating a cross-sectional profile of an active matrix OLED device according to another embodiment; 
         FIG.  26    is a diagram illustrating a cross-sectional profile of an active matrix OLED device according to yet another embodiment; 
         FIG.  27    is a diagram illustrating a cross-sectional profile of an active matrix OLED device according to yet another embodiment; 
         FIG.  28 A  is a diagram illustrating a transparent active matrix OLED device according to one embodiment; 
         FIG.  28 B  is a diagram illustrating a cross-sectional profile of the device according to  FIG.  28 A ; 
         FIG.  29 A  is a diagram illustrating a transparent active matrix OLED device according to one embodiment; 
         FIG.  29 B  is a diagram illustrating a cross-sectional profile of the device according to one embodiment of  FIG.  29 A ; 
         FIG.  29 C  is a diagram illustrating a cross-sectional profile of the device according to another embodiment of  FIG.  29 A ; 
         FIG.  30    is a flow diagram illustrating the stages for fabricating a device according to one embodiment; 
         FIG.  31 A ,  FIG.  31 B ,  FIGS.  31 C, and  31 D  are schematic diagrams illustrating the various stages of device fabrication according to the embodiment of  FIG.  30   ; 
         FIG.  32    is a schematic diagram illustrating a cross-section of an active matrix OLED device according to yet another embodiment; 
         FIG.  33    is a schematic diagram illustrating a cross-section of an active matrix OLED device according to yet another embodiment; 
         FIG.  34    is a schematic diagram illustrating a cross-section of an active matrix OLED device according to yet another embodiment; 
         FIG.  35    is a schematic diagram illustrating a cross-section of an active matrix OLED device according to yet another embodiment; 
         FIG.  36 A ,  FIG.  36 B ,  FIG.  36 C ,  FIG.  36 D ,  FIG.  36 E ,  FIG.  36 F ,  FIG.  36 G , and  FIG.  36 H  are scanning electron microscopy (SEM) micrographs of samples of Example 3; 
         FIG.  37    is a schematic diagram illustrating the formation of a film nucleus; 
         FIG.  38    is a schematic diagram illustrating the relative energy states of an adatom; 
         FIG.  39    is a schematic diagram illustrating various events taken into consideration under an example simulation model; 
         FIG.  40 A  is an SEM micrograph of a sample area over which a nucleation inhibiting coating has been deposited; 
         FIG.  40 B  is an Auger electron microscopy plot showing the spectra taken from the sample area of  FIG.  40 A ; 
         FIG.  41 A  is an SEM micrograph of a sample area following deposition of a magnesium coating; 
         FIG.  41 B  is an Auger electron microscopy plot showing the spectra taken from the sample area of  FIG.  41 A ; 
         FIG.  42 A  is an SEM micrograph of a sample area in an untreated region disposed between neighboring regions coated with a nucleation inhibiting coating; 
         FIG.  42 B  is an Auger electron microscopy plot showing the spectra taken from the sample area of  FIG.  42 A ; 
         FIG.  43 A  is an SEM micrograph of a sample area following deposition of a magnesium coating; and 
         FIG.  43 B  is an Auger electron microscopy plot showing the spectra taken from the sample area of  FIG.  43 A . 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous components. In addition, numerous specific details are set forth in order to provide a thorough understanding of example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without some of those specific details. In other instances, certain methods, procedures and components have not been described in detail so as not to obscure the example embodiments described herein. 
     In one aspect according to some embodiments, a method for depositing an electrically conductive coating on a surface is provided. In some embodiments, the method is performed in the context of a manufacturing method of an opto-electronic device. In some embodiments, the method is performed in the context of a manufacturing method of another device. In some embodiments, the method includes depositing a nucleation inhibiting coating on a first region of a substrate to produce a patterned substrate. The patterned substrate includes the first region covered by the nucleation inhibiting coating, and a second region of the substrate that is exposed from, or is substantially free of or is substantially uncovered by, the nucleation inhibiting coating. The method also includes treating the patterned substrate to deposit the conductive coating on the second region of the substrate. In some embodiments, a material of the conductive coating includes magnesium. In some embodiments, treating the patterned substrate includes treating both the nucleation inhibiting coating and the second region of the substrate to deposit the conductive coating on the second region of the substrate, while the nucleation inhibiting coating remains exposed from, or is substantially free of or is substantially uncovered by, the conductive coating. In some embodiments, treating the patterned substrate includes performing evaporation or sublimation of a source material used to form the conductive coating, and exposing both the nucleation inhibiting coating and the second region of the substrate to the evaporated source material. 
     As used herein, the term “nucleation inhibiting” is used to refer to a coating or a layer of a material having a surface which exhibits a relatively low affinity towards deposition of an electrically conductive material, such that the deposition of the conductive material on the surface is inhibited, while the term “nucleation promoting” is used to refer to a coating or a layer of a material having a surface which exhibits a relatively high affinity towards deposition of an electrically conductive material, such that the deposition of the conductive material on the surface is facilitated. One measure of nucleation inhibiting or nucleation promoting property of a surface is an initial sticking probability of the surface for an electrically conductive material, such as magnesium. For example, a nucleation inhibiting coating with respect to magnesium can refer to a coating having a surface which exhibits a relatively low initial sticking probability for magnesium vapor, such that deposition of magnesium on the surface is inhibited, while a nucleation promoting coating with respect to magnesium can refer to a coating having a surface which exhibits a relatively high initial sticking probability for magnesium vapor, such that deposition of magnesium on the surface is facilitated. As used herein, the terms “sticking probability” and “sticking coefficient” may be used interchangeably. Another measure of nucleation inhibiting or nucleation promoting property of a surface is an initial deposition rate of an electrically conductive material, such as magnesium, on the surface relative to an initial deposition rate of the conductive material on another (reference) surface, where both surfaces are subjected or exposed to an evaporation flux of the conductive material. 
     As used herein, the terms “evaporation” and “sublimation” are interchangeably used to generally refer to deposition processes in which a source material is converted into a vapor (e.g., by heating) to be deposited onto a target surface in, for example, a solid state. 
     As used herein, a surface (or a certain area of the surface) which is “substantially free of” or “is substantially uncovered by” a material refers to a substantial absence of the material on the surface (or the certain area of the surface). Specifically regarding an electrically conductive coating, one measure of an amount of an electrically conductive material on a surface is a light transmittance, since electrically conductive materials, such as metals including magnesium, attenuate and/or absorb light. Accordingly, a surface can be deemed to be substantially free of an electrically conductive material if the light transmittance is greater than 90%, greater than 92%, greater than 95%, or greater than 98% in the visible portion of the electromagnetic spectrum. Another measure of an amount of a material on a surface is a percentage coverage of the surface by the material, such as where the surface can be deemed to be substantially free of the material if the percentage coverage by the material is no greater than 10%, no greater than 8%, no greater than 5%, no greater than 3%, or no greater than 1%. Surface coverage can be assessed using imaging techniques, such as using transmission electron microscopy, atomic force microscopy, or scanning electron microscopy. 
     Selective Deposition 
       FIG.  1    is a schematic diagram illustrating a process of depositing a nucleation inhibiting coating  140  onto a surface  102  of a substrate  100  according to one embodiment. In the embodiment of  FIG.  1   , a source  120  including a source material is heated under vacuum to evaporate or sublime the source material. The source material includes or substantially consists of a material used to form the nucleation inhibiting coating  140 . The evaporated source material then travels in a direction indicated by arrow  122  towards the substrate  100 . A shadow mask  110  having an aperture or slit  112  is disposed in the path of the evaporated source material such that a portion of a flux travelling through the aperture  112  is selectively incident on a region of the surface  102  of the substrate  100 , thereby forming the nucleation inhibiting coating  140  thereon. 
       FIGS.  2 A- 2 C  illustrate a micro-contact transfer printing process for depositing a nucleation inhibiting coating on a surface of a substrate in one embodiment. Similarly to a shadow mask process, the micro-contact printing process may be used to selectively deposit the nucleation inhibiting coating on a region of a substrate surface. 
       FIG.  2 A  illustrates a first stage of the micro-contact transfer printing process, wherein a stamp  210  including a protrusion  212  is provided with a nucleation inhibiting coating  240  on a surface of the protrusion  212 . As will be understood by persons skilled in the art, the nucleation inhibiting coating  240  may be deposited on the surface of the protrusion  212  using various suitable processes. 
     As illustrated in  FIG.  2 B , the stamp  210  is then brought into proximity of a substrate  100 , such that the nucleation inhibiting coating  240  deposited on the surface of the protrusion  212  is in contact with a surface  102  of the substrate  100 . Upon the nucleation inhibiting coating  240  contacting the surface  102 , the nucleation inhibiting coating  240  adheres to the surface  102  of the substrate  100 . 
     As such, when the stamp  210  is moved away from the substrate  100  as illustrated in  FIG.  2 C , the nucleation inhibiting coating  240  is effectively transferred onto the surface  102  of the substrate  100 . 
     Once a nucleation inhibiting coating has been deposited on a region of a surface of a substrate, a conductive coating may be deposited on remaining uncovered region(s) of the surface where the nucleation inhibiting coating is not present. Turning to  FIG.  3   , a conductive coating source  410  is illustrated as directing an evaporated conductive material towards a surface  102  of a substrate  100 . As illustrated in  FIG.  3   , the conducting coating source  410  may direct the evaporated conductive material such that it is incident on both covered or treated areas (namely, region(s) of the surface  102  with the nucleation inhibiting coating  140  deposited thereon) and uncovered or untreated areas of the surface  102 . However, since a surface of the nucleation inhibiting coating  140  exhibits a relatively low initial sticking coefficient compared to that of the uncovered surface  102  of the substrate  100 , a conductive coating  440  selectively deposits onto the areas of the surface  102  where the nucleation inhibiting coating  140  is not present. For example, an initial deposition rate of the evaporated conductive material on the uncovered areas of the surface  102  may be at least or greater than about 80 times, at least or greater than about 100 times, at least or greater than about 200 times, at least or greater than about 500 times, at least or greater than about 700 times, at least or greater than about 1000 times, at least or greater than about 1500 times, at least or greater than about 1700 times, or at least or greater than about 2000 times an initial deposition rate of the evaporated conductive material on the surface of the nucleation inhibiting coating  140 . The conductive coating  440  may include, for example, pure or substantially pure magnesium. 
     It will be appreciated that although shadow mask patterning and micro-contact transfer printing processes have been illustrated and described above, other processes may be used for selectively patterning a substrate by depositing a nucleation inhibiting material. Various additive and subtractive processes of patterning a surface may be used to selectively deposit a nucleation inhibiting coating. Examples of such processes include, but are not limited to, photolithography, printing (including ink or vapor jet printing and reel-to-reel printing), organic vapor phase deposition (OVPD), and laser induced thermal imaging (LITI) patterning, and combinations thereof. 
     In some applications, it may be desirable to deposit a conductive coating having specific material properties onto a substrate surface on which the conductive coating cannot be readily deposited. For example, pure or substantially pure magnesium typically cannot be readily deposited onto some organic surface due to low sticking coefficients of magnesium on some organic surfaces. Accordingly, in some embodiments, the substrate surface is further treated by depositing a nucleation promoting coating thereon prior to depositing the conductive coating, such as one including magnesium. 
     Based on findings and experimental observations, it is postulated that fullerenes and other nucleation promoting materials, as will be explained further herein, act as nucleation sites for the deposition of a conductive coating including magnesium. For example, in cases where magnesium is deposited using an evaporation process on a fullerene treated surface, the fullerene molecules act as nucleation sites that promote formation of stable nuclei for magnesium deposition. Less than a monolayer of fullerene or other nucleation promoting material may be provided on the treated surface to act as nucleation sites for deposition of magnesium in some cases. As will be understood, treating the surface by depositing several monolayers of a nucleation promoting material may result in a higher number of nucleation sites, and thus a higher initial sticking probability. 
     It will also be appreciated that an amount of fullerene or other material deposited on a surface may be more, or less, than one monolayer. For example, the surface may be treated by depositing 0.1 monolayer, 1 monolayer, 10 monolayers, or more of a nucleation promoting material or a nucleation inhibiting material. As used herein, depositing 1 monolayer of a material refers to an amount of the material to cover a desired area of a surface with a single layer of constituent molecules or atoms of the material. Similarly, as used herein, depositing 0.1 monolayer of a material refers to an amount of the material to cover 10% of a desired area of a surface with a single layer of constituent molecules or atoms of the material. Due to, for example, possible stacking or clustering of molecules or atoms, an actual thickness of a deposited material may be non-uniform. For example, depositing 1 monolayer of a material may result in some regions of a surface being uncovered by the material, while other regions of the surface may have multiple atomic or molecular layers deposited thereon. 
     As used herein, the term “fullerene” refers to a material including carbon molecules. Examples of fullerene molecules include carbon cage molecules including a three-dimensional skeleton that includes multiple carbon atoms, which form a closed shell, and which can be spherical or semi-spherical in shape. A fullerene molecule can be designated as Cn, where n is an integer corresponding to a number of carbon atoms included in a carbon skeleton of the fullerene molecule. Examples of fullerene molecules include C n , where n is in the range of 50 to 250, such as C 60 , C 70 , C 72 , C 74 , C 76 , C 78 , C 80 , C 82 , and C 84 . Additional examples of fullerene molecules include carbon molecules in a tube or cylindrical shape, such as single-walled carbon nanotubes and multi-walled carbon nanotubes. 
       FIG.  4    illustrates an embodiment of a device in which a nucleation promoting coating  160  is deposited prior to the deposition of a conductive coating  440 . As illustrated in  FIG.  4   , the nucleation promoting coating  160  is deposited over regions of the substrate  100  that are uncovered by a nucleation inhibiting coating  140 . Accordingly, when the conductive coating  440  is deposited, the conductive coating  440  forms preferentially over the nucleation promoting coating  160 . For example, an initial deposition rate of a material of the conductive coating  440  on a surface of the nucleation promoting coating  160  may be at least or greater than about 80 times, at least or greater than about 100 times, at least or greater than about 200 times, at least or greater than about 500 times, at least or greater than about 700 times, at least or greater than about 1000 times, at least or greater than about 1500 times, at least or greater than about 1700 times, or at least or greater than about 2000 times an initial deposition rate of the material on a surface of the nucleation inhibiting coating  140 . In general, the nucleation promoting coating  160  may be deposited on the substrate  100  prior to, or following, the deposition of the nucleation inhibiting coating  140 . Various processes for selectively depositing a material on a surface may be used to deposit the nucleation promoting coating  160  including, but not limited to, evaporation (including thermal evaporation and electron beam evaporation), photolithography, printing (including ink or vapor jet printing, reel-to-reel printing, and micro-contact transfer printing), OVPD, LITI patterning, and combinations thereof. 
       FIGS.  5 A- 5 C  illustrate a process for depositing a conductive coating onto a surface of a substrate in one embodiment. 
     In  FIG.  5 A , a surface  102  of a substrate  100  is treated by depositing a nucleation inhibiting coating  140  thereon. Specifically, in the illustrated embodiment, deposition is achieved by evaporating a source material inside a source  120 , and directing the evaporated source material towards the surface  102  to be deposited thereon. The general direction in which the evaporated flux is directed towards the surface  102  is indicated by arrow  122 . As illustrated, deposition of the nucleation inhibiting coating  140  may be performed using an open mask or without a mask, such that the nucleation inhibiting coating  140  substantially covers the entire surface  102  to produce a treated surface  142 . Alternatively, the nucleation inhibiting coating  140  may be selectively deposited onto a region of the surface  102  using, for example, a selective deposition technique described above. 
     While the nucleation inhibiting coating  140  is illustrated as being deposited by evaporation, it will be appreciated that other deposition and surface coating techniques may be used, including but not limited to spin coating, dip coating, printing, spray coating, OVPD, LITI patterning, physical vapor deposition (PVD) (including sputtering), chemical vapor deposition (CVD), and combinations thereof. 
     In  FIG.  5 B , a shadow mask  110  is used to selectively deposit a nucleation promoting coating  160  on the treated surface  142 . As illustrated, an evaporated source material travelling from the source  120  is directed towards the substrate  100  through the mask  110 . The mask  110  includes an aperture or slit  112  such that a portion of the evaporated source material incident on the mask  110  is prevented from traveling past the mask  110 , and another portion of the evaporated source material directed through the aperture  112  of the mask  110  selectively deposits onto the treated surface  142  to form the nucleation promoting coating  160 . Accordingly, a patterned surface  144  is produced upon completing the deposition of the nucleation promoting coating  160 . 
       FIG.  5 C  illustrates a stage of depositing a conductive coating  440  onto the patterned surface  144 . The conductive coating  440  may include, for example, pure or substantially pure magnesium. As will be explained further below, a material of the conductive coating  440  exhibits a relatively low initial sticking coefficient with respect to the nucleation inhibiting coating  140  and a relatively high initial sticking coefficient with respect to the nucleation promoting coating  160 . Accordingly, the deposition may be performed using an open mask or without a mask to selectively deposit the conductive coating  440  onto regions of the substrate  100  where the nucleation promoting coating  160  is present. As illustrated in  FIG.  5 C , an evaporated material of the conductive coating  440  that is incident on a surface of the nucleation inhibiting coating  140  may be largely or substantially prevented from being deposited onto the nucleation inhibiting coating  140 . 
       FIGS.  5 D- 5 F  illustrate a process for depositing a conductive coating onto a surface of a substrate in another embodiment. 
     In  FIG.  5 D , a nucleation promoting coating  160  is deposited on a surface  102  of a substrate  100 . For example, the nucleation promoting coating  160  may be deposited by thermal evaporation using an open mask or without a mask. Alternatively, other deposition and surface coating techniques may be used, including but not limited to spin coating, dip coating, printing, spray coating, OVPD, LITI patterning, PVD (including sputtering), CVD, and combinations thereof. 
     In  FIG.  5 E , a nucleation inhibiting coating  140  is selectively deposited over a region of the nucleation promoting coating  160  using a shadow mask  110 . Accordingly, a patterned surface is produced upon completing the deposition of the nucleation inhibiting coating  140 . Then in  FIG.  5 F , a conductive coating  440  is deposited onto the patterned surface using an open mask or a mask-free deposition process, such that the conductive coating  440  is formed over exposed regions of the nucleation promoting coating  160 . 
     In the foregoing embodiments, it will be appreciated that the conductive coating  440  formed by the processes may be used as an electrode or a conductive structure for an electronic device. For example, the conductive coating  440  may be an anode or a cathode of an organic opto-electronic device, such as an OLED device or an organic photovoltaic (OPV) device. In addition, the conductive coating  440  may also be used as an electrode for opto-electronic devices including quantum dots as an active layer material. For example, such a device may include an active layer disposed between a pair of electrodes with the active layer including quantum dots. The device may be, for example, an electroluminescent quantum dot display device in which light is emitted from the quantum dot active layer as a result of current provided by the electrodes. The conductive coating  440  may also be used as a busbar or an auxiliary electrode for any of the foregoing devices. 
     Accordingly, it will be appreciated that the substrate  100  onto which various coatings are deposited may include one or more additional organic and/or inorganic layers not specifically illustrated or described in the foregoing embodiments. For example, in the case of an OLED device, the substrate  100  may include one or more electrodes (e.g., an anode and/or a cathode), charge injection and/or transport layers, and an electroluminescent layer. The substrate  100  may further include one or more transistors and other electronic components such as resistors and capacitors, which are included in an active matrix or a passive matrix OLED device. For example, the substrate  100  may include one or more top-gate thin-film transistors (TFTs), one or more bottom-gate TFTs, and/or other TFT structures. A TFT may be an n-type TFT or a p-type TFT. Examples of TFT structures include those including amorphous silicon (a-Si), indium gallium zinc oxide (IGZO), and low-temperature polycrystalline silicon (LTPS). 
     The substrate  100  may also include a base substrate for supporting the above-identified additional organic and/or inorganic layers. For example, the base substrate may be a flexible or rigid substrate. The base substrate may include, for example, silicon, glass, metal, polymer (e.g., polyimide), sapphire, or other materials suitable for use as the base substrate. 
     The surface  102  of the substrate  100  may be an organic surface or an inorganic surface. For example, if the conductive coating  440  is for use as a cathode of an OLED device, the surface  102  may be provided by a surface of one or more semiconducting layers. For example, the surface  102  may be a top surface of a stack of organic layers. For example, such organic layers may include organic semiconducting layers (e.g., a surface of an electron injection layer). In another example, if the conductive coating  440  is for use as an auxiliary electrode of a top-emission OLED device, the surface  102  may be a top surface of an electrode (e.g., a common cathode). Alternatively, such an auxiliary electrode may be formed directly beneath a transmissive electrode on top of a stack of organic layers. 
       FIG.  6    illustrates an electroluminescent (EL) device  600  according to one embodiment. The EL device  600  may be, for example, an OLED device or an electroluminescent quantum dot device. In one embodiment, the device  600  is an OLED device including a base substrate  616 , an anode  614 , organic layers  630 , and a cathode  602 . In the illustrated embodiment, the organic layers  630  include a hole injection layer  612 , a hole transport layer  610 , an electroluminescent layer  608 , an electron transport layer  606 , and an electron injection layer  604 . 
     The hole injection layer  612  may be formed using a hole injection material which generally facilitates the injection of holes by the anode  614 . The hole transport layer  610  may be formed using a hole transport material, which is generally a material that exhibits high hole mobility. 
     The electroluminescent layer  608  may be formed, for example, by doping a host material with an emitter material. The emitter material may be a fluorescent emitter, a phosphorescent emitter, or a TADF emitter, for example. A plurality of emitter materials may also be doped into the host material to form the electroluminescent layer  608 . 
     The electron transport layer  606  may be formed using an electron transport material which generally exhibits high electron mobility. The electron injection layer  604  may be formed using an electron injection material, which generally acts to facilitate the injection of electrons by the cathode  602 . 
     It will be understood that the structure of the device  600  may be varied by omitting or combining one or more layers. Specifically, one or more of the hole injection layer  612 , the hole transport layer  610 , the electron transport layer  606 , and the electron injection layer  604  may be omitted from the device structure. One or more additional layers may also be present in the device structure. Such additional layers include, for example, a hole blocking layer, an electron blocking layer, and additional charge transport and/or injection layers. Each layer may further include any number of sub-layers, and each layer and/or sub-layer may include various mixtures and composition gradients. It will also be appreciated that the device  600  may include one or more layers containing inorganic and/or organo-metallic materials, and is not limited to devices composed solely of organic materials. For example, the device  600  may include quantum dots. 
     The device  600  may be connected to a power source  620  for supplying current to the device  600 . 
       101171  In another embodiment where the device  600  is an EL quantum dot device, the EL layer  608  generally includes quantum dots, which emit light when current is supplied. 
       FIG.  7    is a flow diagram outlining stages of fabricating an OLED device according to one embodiment. In  704 , organic layers are deposited on a target surface. For example, the target surface may be a surface of an anode that has been deposited on top of a base substrate, which may include, for example, glass, polymer, and/or metal foil. As discussed above, the organic layers may include, for example, a hole injection layer, a hole transport layer, an electroluminescence layer, an electron transport layer, and an electron injection layer. A nucleation inhibiting coating is then deposited on top of the organic layers in stage  706  using a selective deposition or patterning process. In stage  708 , a nucleation promoting coating is selectively deposited on the nucleation inhibiting coating to produce a patterned surface. For example, the nucleation promoting coating and the nucleation inhibiting coating may be selectively deposited by evaporation using a mask, micro-contact transfer printing process, photolithography, printing (including ink or vapor jet printing and reel-to-reel printing), OVPD, or LITI patterning. A conductive coating is then deposited on the patterned surface using an open mask or a mask-free deposition process in stage  710 . The conductive coating may serve as a cathode or another conductive structure of the OLED device. 
     In another embodiment, deposition of the nucleation inhibiting coating in stage  706  may be conducted using an open mask, or without a mask. In yet another embodiment, deposition of the nucleation promoting coating in step  708  may be conducted prior to deposition of the nucleation inhibiting coating in step  706 . In yet another embodiment, deposition of the nucleation promoting coating in step  708  may be conducted using an open mask, or without a mask, prior to selective deposition of the nucleation inhibiting coating in step  706 . 
     For the sake of simplicity and clarity, details of deposited materials including thickness profiles and edge profiles have been omitted from the process diagrams. 
     In accordance with the above-described embodiments, a conductive coating may be selectively deposited on target regions using an open mask or a mask-free deposition process, through the use of a nucleation inhibiting coating or a combination of nucleation inhibiting and nucleation promoting coatings. 
     It will also be appreciated that an open mask used for deposition of any of various layers or coatings, including a conductive coating, a nucleation inhibiting coating, and a nucleation promoting coating, may “mask” or prevent deposition of a material on certain regions of a substrate. However, unlike a fine metal mask (FMM) used to form relatively small features with a feature size on the order of tens of microns or smaller, a feature size of an open mask is generally comparable to the size of an OLED device being manufactured. For example, the open mask may mask edges of a display device during manufacturing, which would result in the open mask having an aperture that approximately corresponds to a size of the display device (e.g., about 1 inch for micro-displays, about 4-6 inches for mobile displays, about 8-17 inches for laptop or tablet displays, and so forth). For example, the feature size of an open mask may be on the order of about 1 cm or greater. Accordingly, an aperture formed in an open mask is typically sized to encompass a plurality of emissive regions or pixels, which together form the display device. 
       FIG.  8 A  illustrates an example of an open mask  1731  having or defining an aperture  1734  formed therein. In the illustrated example, the aperture  1734  of the mask  1731  is smaller than a size of a device  1721 , such that, when the mask  1731  is overlaid, the mask  1731  covers edges of the device  1721 . Specifically, in the illustrated embodiments, all or substantially all emissive regions or pixels  1723  of the device  1721  are exposed through the aperture  1734 , while an unexposed region  1727  is formed between outer edges  1725  of the device  1721  and the aperture  1734 . As would be appreciated, electrical contacts or other device components may be located in the unexposed region  1727  such that these components remain unaffected through the open mask deposition process. 
       FIG.  8 B  illustrates another example of an open mask  1731  where an aperture  1734  of the mask  1731  is smaller than that of  FIG.  8 A , such that the mask  1731  covers at least some emissive regions or pixels  1723  of a device  1721  when overlaid. Specifically, outer-most pixels  1723 ′ are illustrated as being located within an unexposed region  1727  of the device  1721  formed between the aperture  1734  of the mask  1731  and outer edges  1725  of the device  1721 . 
       FIG.  8 C  illustrates yet another example of an open mask  1731  wherein an aperture  1734  of the mask  1731  defines a pattern, which covers some pixels  1723 ′ while exposing other pixels  1723  of a device  1721 . Specifically, the pixels  1723 ′ located within an unexposed region  1727  of the device  1721  (formed between the aperture  1734  and outer edges  1725 ) are masked during the deposition process to inhibit a vapor flux from being incident on the unexposed region  1727 . 
     While outer-most pixels have been illustrated as being masked in the examples of  FIGS.  8 A- 8 C , it will be appreciated that an aperture of an open mask may be shaped to mask other emissive and non-emissive regions of a device. Furthermore, while an open mask has been illustrated in the foregoing examples as having one aperture, the open mask may also include additional apertures for exposing multiple regions of a substrate or a device. 
       FIG.  8 D  illustrates another example of an open mask  1731 , where the mask  1731  has or defines a plurality of apertures  1734   a -1734 d.  The apertures  1734   a -1734 d  are positioned such that they selectively expose certain regions of a device  1721  while masking other regions. For example, certain emissive regions or pixels  1723  are exposed through the apertures  1734   a - d , while other pixels  1723 ′ located within an unexposed region  1727  are masked. 
     In various embodiments described herein, it will be understood that the use of an open mask may be omitted, if desired. Specifically, an open mask deposition process described herein may alternatively be conducted without the use of a mask, such that an entire target surface is exposed. 
     At least some of the above embodiments have been described with reference to various layers or coatings, including a nucleation promoting coating, a nucleation inhibiting coating, and a conductive coating, being formed using an evaporation process. As will be understood, an evaporation process is a type of PVD process where one or more source materials are evaporated or sublimed under a low pressure (e.g., vacuum) environment and deposited on a target surface through de-sublimation of the one or more evaporated source materials. A variety of different evaporation sources may be used for heating a source material, and, as such, it will be appreciated that the source material may be heated in various ways. For example, the source material may be heated by an electric filament, electron beam, inductive heating, or by resistive heating. In addition, such layers or coatings may be deposited and/or patterned using other suitable processes, including photolithography, printing, OVPD, LITI patterning, and combinations thereof. These processes may also be used in combination with a shadow mask to achieve various patterns. 
     For example, magnesium may be deposited at source temperatures up to about 600° C. to achieve a faster rate of deposition, such as about 10 to 30 nm per second or more. Referring to Table  1  below, various deposition rates measured using a Knudsen cell source to deposit substantially pure magnesium on a fullerene-treated organic surface of about 1 nm are provided. It will be appreciated that other factors may also affect a deposition rate including, but not limited to, a distance between a source and a substrate, characteristics of the substrate, presence of a nucleation promoting coating on the substrate, the type of source used and a shaping of a flux of material evaporated from the source. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Magnesium Deposition Rate by Temperature 
               
            
           
           
               
               
               
               
            
               
                   
                 Sample # 
                 Temperature (° C.) 
                 Rate (angstroms/s) 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 1 
                 510 
                 10 
               
               
                   
                 2 
                 525 
                 40 
               
               
                   
                 3 
                 575 
                 140 
               
               
                   
                 4 
                 600 
                 160 
               
               
                   
                   
               
            
           
         
       
     
     It will be appreciated by those skilled in the art that particular processing conditions used may vary depending on an equipment being used to conduct a deposition. It will also be appreciated that higher deposition rates are generally attained at higher source temperatures; however, other deposition conditions can be selected, such as, for example, by placing a substrate closer to a deposition source. 
     Although certain processes have been described with reference to evaporation for purposes of depositing a nucleation promoting material, a nucleation inhibiting material, and magnesium, it will be appreciated that various other processes may be used to deposit these materials. For example, deposition may be conducted using other PVD processes (including sputtering), CVD processes (including plasma enhanced chemical vapor deposition (PECVD)), or other suitable processes for depositing such materials. In some embodiments, magnesium is deposited by heating a magnesium source material using a resistive heater. In other embodiments, a magnesium source material may be loaded in a heated crucible, a heated boat, a Knudsen cell (e.g., an effusion evaporator source), or any other type of evaporation source. 
     A deposition source material used to deposit a conductive coating may be a mixture or a compound, and, in some embodiments, at least one component of the mixture or compound is not deposited on a substrate during deposition (or is deposited in a relatively small amount compared to, for example, magnesium). In some embodiments, the source material may be a copper-magnesium (Cu—Mg) mixture or a Cu—Mg compound. In some embodiments, the source material for a magnesium deposition source includes magnesium and a material with a lower vapor pressure than magnesium, such as, for example, Cu. In other embodiments, the source material for a magnesium deposition source is substantially pure magnesium. Specifically, substantially pure magnesium can exhibit substantially similar properties (e.g., initial sticking probabilities on nucleation inhibiting and promoting coatings) compared to pure magnesium (99.99% and higher purity magnesium). For example, an initial sticking probability of substantially pure magnesium on a nucleation inhibiting coating can be within ±10% or within ±5% of an initial sticking probability of 99.99% purity magnesium on the nucleation inhibiting coating. Purity of magnesium may be about 95% or higher, about 98% or higher, about 99% or higher, or about 99.9% or higher. Deposition source materials used to deposit a conductive coating may include other metals in place of, or in combination with, magnesium. For example, a source material may include high vapor pressure materials, such as ytterbium (Yb), cadmium (Cd), zinc (Zn), or any combination thereof. 
     Furthermore, it will be appreciated that the processes of various embodiments may be performed on surfaces of other various organic or inorganic materials used as an electron injection layer, an electron transport layer, an electroluminescent layer, and/or a pixel definition layer (PDL) of an organic opto-electronic device. Examples of such materials include organic molecules as well as organic polymers such as those described in PCT Publication No. WO 2012/016074. It will also be understood by persons skilled in the art that organic materials doped with various elements and/or inorganic compounds may still be considered to be an organic material. It will further be appreciated by those skilled in the art that various organic materials may be used, and the processes described herein are generally applicable to an entire range of such organic materials. 
     It will also be appreciated that an inorganic substrate or surface can refer to a substrate or surface primarily including an inorganic material. For greater clarity, an inorganic material will generally be understood to be any material that is not considered to be an organic material. Examples of inorganic materials include metals, glasses, and minerals. Specifically, a conductive coating including magnesium may be deposited using a process according to the present disclosure on surfaces of lithium fluoride (LiF), glass and silicon (Si). Other surfaces on which the processes according to the present disclosure may be applied include those of silicon or silicone-based polymers, inorganic semiconductor materials, electron injection materials, salts, metals, and metal oxides. 
     It will be appreciated that a substrate may include a semiconductor material, and, accordingly, a surface of such a substrate may be a semiconductor surface. A semiconductor material may be described as a material which generally exhibits a band gap. For example, such a band gap may be formed between a highest occupied molecular orbital (HOMO) and a lowest unoccupied molecular orbital (LUMO). Semiconductor materials thus generally possess electrical conductivity that is less than that of a conductive material (e.g., a metal) but greater than that of an insulating material (e.g., a glass). It will be understood that a semiconductor material may be an organic semiconductor material or an inorganic semiconductor material. 
     Selective Deposition of an Electrode 
       FIGS.  9  and  10    illustrates an OLED device  1500  according to one embodiment. Specifically,  FIG.  9    shows a top view of the OLED device  1500 , and  FIG.  10    illustrates a cross-sectional view of a structure of the OLED device  1500 . In  FIG.  9   , a cathode  1550  is illustrated as a single monolithic or continuous structure having or defining a plurality of apertures or holes  1560  formed therein, which correspond to regions of the device  1500  where a cathode material was not deposited. This is further illustrated in  FIG.  10   , which shows the OLED device  1500  including a base substrate  1510 , an anode  1520 , organic layers  1530 , a nucleation promoting coating  1540 , a nucleation inhibiting coating  1570  selectively deposited over certain regions of the nucleation promoting coating  1540 , and the cathode  1550  deposited over other regions of the nucleation promoting coating  1540  where the nucleation inhibiting coating  1570  is not present. More specifically, by selectively depositing the nucleation inhibiting coating  1570  to cover certain regions of a surface of the nucleation promoting coating  1540  during the fabrication of the device  1500 , the cathode material is selectively deposited on exposed regions of the surface of the nucleation promoting coating  1540  using an open mask or a mask-free deposition process. The transparency or transmittance of the OLED device  1500  may be adjusted or modified by changing various parameters of an imparted pattern, such as an average size of the holes  1560  and a density of the holes  1560  formed in the cathode  1550 . Accordingly, the OLED device  1500  may be a substantially transparent OLED device, which allows at least a portion of an external light incident on the OLED device to be transmitted therethrough. For example, the OLED device  1500  may be a substantially transparent OLED lighting panel. Such OLED lighting panel may be, for example, configured to emit light in one direction (e.g., either towards or away from the base substrate  1510 ) or in both directions (e.g., towards and away from the base substrate  1510 ). 
       FIG.  11    illustrates an OLED device  1600  according to another embodiment in which a cathode  1650  substantially covers an entire device area. Specifically, the OLED device  1600  includes a base substrate  1610 , an anode  1620 , organic layers  1630 , a nucleation promoting coating  1640 , the cathode  1650 , a nucleation inhibiting coating  1660  selectively deposited over certain regions of the cathode  1650 , and an auxiliary electrode  1670  deposited over other regions of the cathode  1650  where the nucleation inhibiting coating  1660  is not present. 
     The auxiliary electrode  1670  is electrically connected to the cathode  1650 . Particularly in a top-emission configuration, it is desirable to deposit a relatively thin layer of the cathode  1650  to reduce optical interference (e.g., attenuation, reflection, diffusion, and so forth) due to the presence of the cathode  1650 . However, a reduced thickness of the cathode  1650  generally increases a sheet resistance of the cathode  1650 , thus reducing the performance and efficiency of the OLED device  1600 . By providing the auxiliary electrode  1670  that is electrically connected to the cathode  1650 , the sheet resistance and thus the IR drop associated with the cathode  1650  can be decreased. Furthermore, by selectively depositing the auxiliary electrode  1670  to cover certain regions of the device area while other regions remain uncovered, optical interference due to the presence of the auxiliary electrode  1670  may be controlled and/or reduced. 
     While the advantages of auxiliary electrodes have been explained in reference to top-emission OLED devices, it may also be advantageous to selectively deposit an auxiliary electrode over a cathode of a bottom-emission or double-sided emission OLED device. For example, while the cathode may be formed as a relatively thick layer in a bottom-emission OLED device without substantially affecting optical characteristics of the device, it may still be advantageous to form a relatively thin cathode. For example, in a transparent or semi-transparent display device, layers of the entire device including a cathode can be formed to be substantially transparent or semi-transparent. Accordingly, it may be beneficial to provide a patterned auxiliary electrode which cannot be readily detected by a naked eye from a typical viewing distance. It will also be appreciated that the described processes may be used to form busbars or auxiliary electrodes for decreasing a resistance of electrodes for devices other than OLED devices. 
       FIG.  12 A  shows a patterned cathode  1712  according to one embodiment, in which the cathode  1712  includes a plurality of spaced apart and elongated conductive strips. For example, the cathode  1712  may be used in a passive matrix OLED device (PMOLED)  1715 . In the PMOLED device  1715 , emissive regions or pixels are generally formed at regions where counter-electrodes overlap. Accordingly, in the embodiment of  FIG.  12 A , emissive regions or pixels  1751  are formed at overlapping regions of the cathode  1712  and an anode  1741 , which includes a plurality of spaced apart and elongated conductive strips. Non-emissive regions  1755  are formed at regions where the cathode  1712  and the anode  1741  do not overlap. Generally, the strips of the cathode  1712  and the strips of the anode  1741  are oriented substantially perpendicular to each other in the PMOLED device  1715  as illustrated. The cathode  1712  and the anode  1741  may be connected to a power source and associated driving circuitry for supplying current to the respective electrodes. 
       FIG.  12 B  illustrates a cross-sectional view taken along line A-A in  FIG.  12 A . In  FIG.  12 B , a base substrate  1702  is provided, which may be, for example, a transparent substrate. The anode  1741  is provided over the base substrate  1702  in the form of strips as illustrated in  FIG.  12 A . One or more organic layers  1761  are deposited over the anode  1741 . For example, the organic layers  1761  may be provided as a common layer across the entire device, and may include any number of layers of organic and/or inorganic materials described herein, such as hole injection and transport layers, an electroluminescence layer, and electron transport and injection layers. Certain regions of a top surface of the organic layers  1761  are illustrated as being covered by a nucleation inhibition coating  1771 , which is used to selectively pattern the cathode  1712  in accordance with the deposition processes described above. The cathode  1712  and the anode  1741  may be connected to their respective drive circuitry (not shown), which controls emission of light from the pixels  1751 . 
     While thicknesses of the nucleation inhibiting coating  1771  and the cathode  1712  may be varied depending on the desired application and performance, at least in some embodiments, the thickness of the nucleation inhibiting coating  1771  may be comparable to, or substantially less than, the thickness of the cathode  1712  as illustrated in  FIG.  12 B . The use of a relatively thin nucleation inhibiting coating to achieve patterning of a cathode may be particularly advantageous for flexible PMOLED devices, since it can provide a relatively planar surface onto which a barrier coating may be applied. 
       FIG.  12 C  illustrates the PMOLED device  1715  of  FIG.  12 B  with a barrier coating  1775  applied over the cathode  1712  and the nucleation inhibiting coating  1771 . As will be appreciated, the barrier coating  1775  is generally provided to inhibit the various device layers, including organic layers and the cathode  1712  which may be prone to oxidation, from being exposed to moisture and ambient air. For example, the barrier coating  1775  may be a thin film encapsulation formed by printing, CVD, sputtering, atomic-layer deposition (ALD), any combinations of the foregoing, or by any other suitable methods. The barrier coating  1775  may also be provided by laminating a pre-formed barrier film onto the device  1715  using an adhesive (not shown). For example, the barrier coating  1775  may be a multi-layer coating comprising organic materials, inorganic materials, or combination of both. The barrier coating  1775  may further comprise a getter material and/or a desiccant. 
     For comparative purposes, an example of a comparative PMOLED device  1719  is illustrated in  FIG.  12 D . In the comparative example of  FIG.  12 D , a plurality of pixel definition structures  1783  are provided in non-emissive regions of the device  1719 , such that when a conductive material is deposited using an open mask or a mask-free deposition process, the conductive material is deposited on both emissive regions located between neighboring pixel definition structures  1783  to form the cathode  1712 , as well as on top of the pixel definition structures  1783  to form conductive strips  1718 . However, in order to ensure that each segment of the cathode  1712  is electrically isolated from the conductive strips  1718 , a thickness or height of the pixel definition structures  1783  are formed to be greater than a thickness of the cathode  1712 . The pixel definition structures  1783  may also have an undercut profile to further decrease the likelihood of the cathode  1712  coming in electrical contact with the conductive strips  1718 . The barrier coating  1775  is provided to cover the PMOLED device  1719  including the cathode  1712 , the pixel definition structures  1783 , and the conductive strips  1718 . 
     In the comparative PMOLED device  1719  illustrated in  FIG.  12 D , the surface onto which the barrier coating  1775  is applied is non-uniform due to the presence of the pixel definition structures  1783 . This makes the application of the barrier coating  1775  difficult, and even upon the application of the barrier coating  1775 , the adhesion of the barrier coating  1775  to the underlying surface may be relatively poor. Poor adhesion increases the likelihood of the barrier coating  1775  peeling off the device  1719 , particularly when the device  1719  is bent or flexed. Additionally, there is a relatively high probability of air pockets being trapped between the barrier coating  1775  and the underlying surface during the application procedure due to the non-uniform surface. The presence of air pockets and/or peeling of the barrier coating  1775  can cause or contribute to defects and partial or total device failure, and thus is highly undesirable. These factors are mitigated or reduced in the embodiment of  FIG.  12 C . 
     While the patterned cathode  1712  shown in  FIG.  12 A  may be used to form a cathode of an OLED device, it is appreciated that a similar patterning or selective deposition technique may be used to form an auxiliary electrode for an OLED device. Specifically, such an OLED device may be provided with a common cathode, and an auxiliary electrode deposited on top of, or beneath, the common cathode such that the auxiliary electrode is in electrical communication with the common cathode. For example, such an auxiliary electrode may be implemented in an OLED device including a plurality of emissive regions (e.g., an active matrix OLED device) such that the auxiliary electrode is formed over non-emissive regions, and not over the emissive regions. In another example, an auxiliary electrode may be provided to cover non-emissive regions as well as at least some emissive regions of an OLED device. 
     Selective Deposition of an Auxiliary Electrode 
       FIG.  13 A  depicts a portion of an OLED device  1800  including a plurality of emissive regions  1810   a -1810 f  and a non-emissive region  1820 . For example, the OLED device  1800  may be an active matrix OLED (AMOLED) device, and each of the emissive regions  1810   a -1810 f  may correspond to a pixel or a subpixel of such a device. For sake of simplicity,  FIGS.  13 B- 13 D  depict a portion of the OLED device  1800 . Specifically,  FIGS.  13 B- 13 D  show a region surrounding a first emissive region  1810   a  and a second emissive region  1810   b,  which are two neighboring emissive regions. While not explicitly illustrated, a common cathode may be provided that substantially covers both emissive regions and non-emissive regions of the device  1800 . 
     In  FIG.  13 B , an auxiliary electrode  1830  according to one embodiment is shown, in which the auxiliary electrode  1830  is disposed between the two neighboring emissive regions  1810   a  and  1810   b.  The auxiliary electrode  1830  is electrically connected to the common cathode (not shown). Specifically, the auxiliary electrode  1830  is illustrated as having a width (a), which is less than a separation distance (d) between the neighboring emissive regions  1810   a  and  1810   b,  thus creating a non-emissive gap region on each side of the auxiliary electrode  1830 . For example, such an arrangement may be desirable in the device  1800  where the separation distance between the neighboring emissive regions  1810   a  and  1810   b  are sufficient to accommodate the auxiliary electrode  1830  of sufficient width, since the likelihood of the auxiliary electrode  1830  interfering with an optical output of the device  1800  can be reduced by providing the non-emissive gap regions. Furthermore, such an arrangement may be particularly beneficial in cases where the auxiliary electrode  1830  is relatively thick (e.g., greater than several hundred nanometers or on the order a few microns thick). For example, a ratio of a height or a thickness of the auxiliary electrode  1830  relative to its width (namely, an aspect ratio) may be greater than about 0.05, such as about 0.1 or greater, about 0.2 or greater, about 0.5 or greater, about 0.8 or greater, about 1 or greater, or about 2 or greater. For example, the height or the thickness of the auxiliary electrode  1830  may be greater than about 50 nm, such as about 80 nm or greater, about 100 nm or greater, about 200 nm or greater, about 500 nm or greater, about 700 nm or greater, about 1000 nm or greater, about 1500 nm or greater, about 1700 nm or greater, or about 2000 nm or greater. 
     In  FIG.  13 C , an auxiliary electrode  1832  according to another embodiment is shown. The auxiliary electrode  1832  is electrically connected to the common cathode (not shown). As illustrated, the auxiliary electrode  1832  has substantially the same width as the separation distance between the two neighboring emissive regions  1810   a  and  1810   b,  such that the auxiliary electrode  1832  substantially fully occupies the entire non-emissive region provided between the neighboring emissive regions  1810   a  and  1810   b.  Such an arrangement may be desirable, for example, in cases where the separation distance between the two neighboring emissive regions  1810   a  and  1810   b  is relatively small, such as in a high pixel density display device. 
     In  FIG.  13 D , an auxiliary electrode  1834  according to yet another embodiment is illustrated. The auxiliary electrode  1834  is electrically connected to the common cathode (not shown). The auxiliary electrode  1834  is illustrated as having a width (a), which is greater than the separation distance (d) between the two neighboring emissive regions  1810   a  and  1810   b.  Accordingly, a portion of the auxiliary electrode  1834  overlaps a portion of the first emissive region  1810   a  and a portion of the second emissive region  1810   b.  Such an arrangement may be desirable, for example, in cases where the non-emissive region between the neighboring emissive regions  1810   a  and  1810   b  is not sufficient to fully accommodate the auxiliary electrode  1834  of the desired width. While the auxiliary electrode  1834  is illustrated in  FIG.  13 D  as overlapping with the first emissive region  1810   a  to substantially the same degree as the second emissive region  1810   b,  the extent to which the auxiliary electrode  1834  overlaps with an adjacent emissive region may be modulated in other embodiments. For example, in other embodiments, the auxiliary electrode  1834  may overlap to a greater extent with the first emissive region  1810   a  than the second emissive region  1810   b  and vice versa. Furthermore, a profile of overlap between the auxiliary electrode  1834  and an emissive region can also be varied. For example, an overlapping portion of the auxiliary electrode  1834  may be shaped such that the auxiliary electrode  1834  overlaps with a portion of an emissive region to a greater extent than it does with another portion of the same emissive region to create a non-uniform overlapping region. 
       FIG.  14    illustrates an embodiment in which an auxiliary electrode  2530  is formed as a grid over an OLED device  2500 . As illustrated, the auxiliary electrode is  2530  provided over a non-emissive region  2520  of the device  2500 , such that it does not substantially cover any portion of emissive regions  2510 . 
     While the auxiliary electrode has been illustrated as being formed as a connected and continuous structure in the embodiment of  FIG.  14   , it will be appreciated that in some embodiments, the auxiliary electrode may be provided in the form of discrete auxiliary electrode units wherein the discrete auxiliary electrode units are not physically connected to one another. However, even in such cases, the auxiliary electrode units may be nevertheless in electrical communication with one another via a common electrode. For example, providing discrete auxiliary electrode units, which are indirectly connected to one another via the common electrode, may still substantially lower a sheet resistance and thus increase an efficiency of an OLED device without substantially interfering with optical characteristics of the device. 
     Auxiliary electrodes may be used in display devices with various pixel or sub-pixel arrangements. For example, auxiliary electrodes may be provided on a display device in which a diamond pixel arrangement is used. Examples of such pixel arrangements are illustrated in  FIGS.  15 - 17   . 
       FIG.  15    is a schematic illustration of an OLED device  2900  having a diamond pixel arrangement according to one embodiment. The OLED device  2900  includes a plurality of pixel definition layers (PDLs)  2930  and emissive regions  2912  (sub-pixels) disposed between neighboring PDLs  2930 . The emissive regions  2912  include those corresponding to first sub-pixels  2912   a,  which may, for example, correspond to green sub-pixels, second sub-pixels  2912   b,  which may, for example, correspond to blue sub-pixels, and third sub-pixels  2912   c,  which may, for example, correspond to red sub-pixels. 
       FIG.  16    is a schematic illustration of the OLED device  2900  taken along line A-A shown in  FIG.  15   . As more clearly illustrated in  FIG.  16   , the device  2900  includes a substrate  2903  and a plurality of anode units  2921  formed on a surface of the base substrate  2903 . The substrate  2903  may further include a plurality of transistors and a base substrate, which have been omitted from the figure for sake of simplicity. An organic layer  2915  is provided on top of each anode unit  2921  in a region between neighboring PDLs  2930 , and a common cathode  2942  is provided over the organic layer  2915  and the PDLs  2930  to form the first sub-pixels  2912   a.  The organic layer  2915  may include a plurality of organic and/or inorganic layers. For example, such layers may include a hole transport layer, a hole injection layer, an electroluminescence layer, an electron injection layer, and/or an electron transport layer. A nucleation inhibiting coating  2945  is provided over regions of the common cathode  2942  corresponding to the first sub-pixels  2912   a  to allow selective deposition of an auxiliary electrode  2951  over uncovered regions of the common cathode  2942  corresponding to substantially planar regions of the PDLs  2930 . The nucleation inhibiting coating  2945  may also act as an index-matching coating. A thin film encapsulation layer  2961  may optionally be provided to encapsulate the device  2900 . 
       FIG.  17    shows a schematic illustration of the OLED device  2900  taken along line B-B indicated in  FIG.  15   . The device  2900  includes the plurality of anode units  2921  formed on the surface of the substrate  2903 , and an organic layer  2916  or  2917  provided on top of each anode unit  2921  in a region between neighboring PDLs  2930 . The common cathode  2942  is provided over the organic layers  2916  and  2917  and the PDLs  2930  to form the second sub-pixel  2912   b  and the third sub-pixel  2912   c,  respectively. The nucleation inhibiting coating  2945  is provided over regions of the common cathode  2942  corresponding to the sub-pixels  2912   b  and  2912   c  to allow selective deposition of the auxiliary electrode  2951  over uncovered regions of the common cathode  2942  corresponding to the substantially planar regions of the PDLs  2930 . The nucleation inhibiting coating  2945  may also act as an index-matching coating. The thin film encapsulation layer  2961  may optionally be provided to encapsulate the device  2900 . 
     In another aspect according to some embodiments, a device is provided. In some embodiments, the device is an opto-electronic device. In some embodiments, the device is another electronic device or other product. In some embodiments, the device includes a substrate, a nucleation inhibiting coating, and a conductive coating. The nucleation inhibiting coating covers a first region of the substrate. The conductive coating covers a second region of the substrate, and partially overlaps the nucleation inhibiting coating such that at least a portion of the nucleation inhibiting coating is exposed from, or is substantially free of or is substantially uncovered by, the conductive coating. In some embodiments, the conductive coating includes a first portion and a second portion, the first portion of the conductive coating covers the second region of the substrate, and the second portion of the conductive coating overlaps a portion of the nucleation inhibiting coating. In some embodiments, the second portion of the conductive coating is spaced from the nucleation inhibiting coating by a gap. In some embodiments, the nucleation inhibiting coating includes an organic material. In some embodiments, the first portion of the conductive coating and the second portion of the conductive coating are formed integral or continuous with one another to provide a single monolithic structure. 
     j In another aspect according to some embodiments, a device is provided. In some embodiments, the device is an opto-electronic device. In some embodiments, the device is another electronic device or other product. In some embodiments, the device includes a substrate and a conductive coating. The substrate includes a first region and a second region. The conductive coating covers the second region of the substrate, and partially overlaps the first region of the substrate such that at least a portion of the first region of the substrate is exposed from, or is substantially free of or is substantially uncovered by, the conductive coating. In some embodiments, the conductive coating includes a first portion and a second portion, the first portion of the conductive coating covers the second region of the substrate, and the second portion of the conductive coating overlaps a portion of the first region of the substrate. In some embodiments, the second portion of the conductive coating is spaced from the first region of the substrate by a gap. In some embodiments, the first portion of the conductive coating and the second portion of the conductive coating are integrally formed with one another. 
       FIG.  18    illustrates a portion of a device according to one embodiment. The device includes a substrate  3410  having a surface  3417 . A nucleation inhibiting coating  3420  covers a first region  3415  of the surface  3417  of the substrate  3410 , and a conductive coating  3430  covers a second region  3412  of the surface  3417  of the substrate  3410 . As illustrated in  FIG.  18   , the first region  3415  and the second region  3412  are distinct and non-overlapping regions of the surface  3417  of the substrate  3410 . The conductive coating  3430  includes a first portion  3432  and a second portion  3434 . As illustrated in the figure, the first portion  3432  of the conductive coating  3430  covers the second region  3412  of the substrate  3410 , and the second portion  3434  of the conductive coating  3430  partially overlaps a portion of the nucleation inhibiting coating  3420 . Specifically, the second portion  3434  is illustrated as overlapping the portion of the nucleation inhibiting coating  3420  in a direction that is perpendicular (or normal) to the underlying substrate surface  3417 . 
     Particularly in the case where the nucleation inhibiting coating  3420  is formed such that its surface  3422  exhibits a relatively low affinity or initial sticking probability against a material used to form the conductive coating  3430 , there is a gap  3441  formed between the overlapping, second portion  3434  of the conductive coating  3430  and the surface  3422  of the nucleation inhibiting coating  3420 . Accordingly, the second portion  3434  of the conductive coating  3430  is not in direct physical contact with the nucleation inhibiting coating  3420 , but is spaced from the nucleation inhibiting coating  3420  by the gap  3441  along the direction perpendicular to the surface  3417  of the substrate  3410  as indicated by arrow  3490 . Nevertheless, the first portion  3432  of the conductive coating  3430  may be in direct physical contact with the nucleation inhibiting coating  3420  at an interface or a boundary between the first region  3415  and the second region  3412  of the substrate  3410 . 
     In some embodiments, the overlapping, second portion  3434  of the conductive coating  3430  may laterally extend over the nucleation inhibiting coating  3420  by a comparable extent as a thickness of the conductive coating  3430 . For example, in reference to  FIG.  18   , a width W 2  (or a dimension along a direction parallel to the surface  3417  of the substrate  3410 ) of the second portion  3434  may be comparable to a thickness t 1  (or a dimension along a direction perpendicular to the surface  3417  of the substrate  3410 ) of the first portion  3432  of the conductive coating  3430 . For example, a ratio of w 2 : t 1  may be in a range of about 1:1 to about 1:3, about 1:1 to about 1:1.5, or about 1:1 to about 1:2. While the thickness t 1  would generally be relatively uniform across the conductive coating  3430 , the extent to which the second portion  3434  overlaps with the nucleation inhibiting coating  3420  (namely, W 2 ) may vary to some extent across different portions of the surface  3417 . 
     In another embodiment illustrated in  FIG.  19   , the conductive coating  3430  further includes a third portion  3436  disposed between the second portion  3434  and the nucleation inhibiting coating  3420 . As illustrated, the second portion  3434  of the conductive coating  3430  laterally extends over and is spaced from the third portion  3436  of the conductive coating  3430 , and the third portion  3436  may be in direct physical contact with the surface  3422  of the nucleation inhibiting coating  3420 . A thickness t 3  of the third portion  3436  may be less, and, in some cases, substantially less than the thickness t 1  of the first portion  3432  of the conductive coating  3430 . Furthermore, at least in some embodiments, a width  14 ) 3  of the third portion  3436  may be greater than the width W 2  of the second portion  3434 . Accordingly, the third portion  3436  may extend laterally to overlap with the nucleation inhibiting coating  3420  to a greater extent than the second portion  3434 . For example, a ratio of w 3 :t 1  may be in a range of about 1:2 to about 3:1 or about 1:1.2 to about 2.5:1. While the thickness t 1  would generally be relatively uniform across the conductive coating  3430 , the extent to which the third portion  3436  overlaps with the nucleation inhibiting coating  3420  (namely, w 3 ) may vary to some extent across different portions of the surface  3417 . The thickness t 3  of the third portion  3436  may be no greater than or less than about 5% of the thickness t 1  of the first portion  3432 . For example, t 3  may be no greater than or less than about 4%, no greater than or less than about 3%, no greater than or less than about 2%, no greater than or less than about 1%, or no greater than or less than about 0.5% of t 1 . Instead of, or in addition to, the third portion  3436  being formed as a thin film as shown in  FIG.  19   , the material of the conductive coating  3430  may form as islands or disconnected clusters on a portion of the nucleation inhibiting coating  3420 . For example, such islands or disconnected clusters may include features which are physically separated from one another, such that the islands or clusters are not formed as a continuous layer. 
     In yet another embodiment illustrated in  FIG.  20 A , a nucleation promoting coating  3451  is disposed between the substrate  3410  and the conductive coating  3430 . Specifically, the nucleation promoting coating  3451  is disposed between the first portion  3432  of the conducting coating  3430  and the second region  3412  of the substrate  3410 . The nucleation promoting coating  3451  is illustrated as being disposed on the second region  3412  of the substrate  3410 , and not on the first region  3415  where the nucleation inhibiting coating  3420  is deposited. The nucleation promoting coating  3451  may be formed such that, at an interface or a boundary between the nucleation promoting coating  3451  and the conductive coating  3430 , a surface of the nucleation promoting coating  3451  exhibits a relatively high affinity or initial sticking probability for the material of the conductive coating  3430 . As such, the presence of the nucleation promoting coating  3451  may promote the formation and growth of the conductive coating  3430  during deposition. Various features of the conductive coating  3430  (including the dimensions of the first portion  3432  and the second portion  3434 ) and other coatings of  FIG.  20 A  can be similar to those described above for  FIG.  18 - 19    and are not repeated for brevity. 
     In yet another embodiment illustrated in  FIG.  20 B , the nucleation promoting coating  3451  is disposed on both the first region  3415  and the second region  3412  of the substrate  3410 , and the nucleation inhibiting coating  3420  covers a portion of the nucleation promoting coating  3451  disposed on the first region  3415 . Another portion of the nucleation promoting coating  3451  is exposed from, or is substantially free of or is substantially uncovered by, the nucleation inhibiting coating  3420 , and the conductive coating  3430  covers the exposed portion of the nucleation promoting coating  3451 . Various features of the conducting coating  3430  and other coatings of  FIG.  20 B  can be similar to those described above for  FIG.  18 - 19    and are not repeated for brevity. 
       FIG.  21    illustrates a yet another embodiment in which the conductive coating  3430  partially overlaps a portion of the nucleation inhibiting coating  3420  in a third region  3419  of the substrate  3410 . Specifically, in addition to the first portion  3432  and the second portion  3434 , the conductive coating  3430  further includes a third portion  3480 . As illustrated in the figure, the third portion  3480  of the conductive coating  3430  is disposed between the first portion  3432  and the second portion  3434  of the conductive coating  3430 , and the third portion  3480  may be in direct physical contact with the surface  3422  of the nucleation inhibiting coating  3420 . In this regard, the overlap in the third region  3419  may be formed as a result of lateral growth of the conductive coating  3430  during an open mask or mask-free deposition process. More specifically, while the surface  3422  of the nucleation inhibiting coating  3420  may exhibit a relatively low initial sticking probability for the material of the conductive coating  3430  and thus the probability of the material nucleating on the surface  3422  is low, as the conductive coating  3430  grows in thickness, the coating  3430  may also grow laterally and may cover a portion of the nucleation inhibiting coating  3420  as illustrated in  FIG.  21   . 
     While details regarding certain features of the device and the conductive coating  3430  have been omitted in the above description for the embodiments of  FIGS.  20 A- 21   , it will be appreciated that descriptions of various features including the gap  3441 , the second portion  3434 , and the third portion  3436  of the conductive coating  3430  described in relation to  FIG.  18    and  FIG.  19    would similarly apply to such embodiments. 
       FIG.  22 A  illustrates a yet another embodiment wherein the first region  3415  of the substrate  3410  is coated with the nucleation inhibiting coating  3420 , and the second region  3412  adjacent to the first region  3415  is coated with the conductive coating  3430 . 
     It has been observed that, at least in some cases, conducting the open mask or mask-free deposition of the conductive coating  3430  over a substrate surface which has been partially coated with the nucleation inhibiting coating  3420  can result in the formation of the conductive coating  3430  exhibiting a tapered cross-sectional profile at or near the interface between the conductive coating  3430  and the nucleation inhibiting coating  3420 . 
       FIG.  22 A  illustrates one embodiment in which the thickness of the conductive coating  3430  is reduced at, near, or adjacent to the interface between the conductive coating  3430  and the nucleation inhibiting coating  3420  due to the tapered profile of the conductive coating  3430 . Specifically, the thickness of the conductive coating  3430  at or near the interface is less than the average thickness of the conductive coating  3430 . While the tapered profile of the conductive coating  3430  is illustrated as being curved or arched (e.g., with a convex shape) in the embodiment of  FIG.  22 A , the profile may be substantially linear or non-linear (e.g., with a concave shape) in other embodiments. For example, the thickness of the conductive coating  3430  may decrease in substantially linear, exponential, quadratic, or other manner in the region proximal to the interface. 
     During the nucleation stage of a thin film formation process, molecules in a vapor phase condense onto a surface of a substrate to form nuclei. Without wishing to be bound by a particular theory, it is postulated that the shapes and sizes of these nuclei and the subsequent growth of these nuclei into islands and then into a thin film, depend on a number of factors, such as the interfacial tensions between the vapor, substrate, and the condensed film nuclei. It is further postulated that, during thin film nucleation and growth at or near the interface between an exposed surface of the substrate and a nucleation inhibiting coating, a relatively large contact angle between the edge of the film and the substrate would be observed due to “dewetting” of the solid surface of the thin film by the nucleation inhibiting coating. This dewetting property is driven by the minimization of surface energy between the substrate, thin film, vapor and nucleation inhibiting coating. Accordingly, it is postulated that the presence of the nucleation inhibiting coating and the properties of the nucleation inhibiting coating have a significant effect on the nuclei formation and the growth mode of the edge of the conductive coating. 
     It has been observed that a contact angle of the conductive coating  3430  at or near the interface between the conductive coating  3430  and the nucleation inhibiting coating  3420  can vary depending on properties of the nucleation inhibiting coating  3420 , such as the relative affinity or the initial sticking probability. It is further postulated that the contact angle of the nuclei may dictate the thin film contact angle of the conductive coating  3430  formed by deposition. Referring to  FIG.  22 A  for example, the contact angle,  8 , may be determined by measuring a slope of a tangent of an edge of the conductive coating  3430  at or near the interface between the conductive coating  3430  and the nucleation inhibiting coating  3420 . In other examples where the cross-sectional taper profile of the conductive coating  3430  is substantially linear, the contact angle may be determined by measuring the slope of the conductive coating  3430  at or near the interface. As would be appreciated, the contact angle is generally measured relative to an angle of the underlying surface of the substrate  3410 . For sake of simplicity, the embodiments provided herein have been illustrated to show the coatings deposited on a planar surface, however it will be appreciated that the coatings may be deposited on non-planar surfaces. 
     Referring to  FIG.  22 A , the contact angle of the conductive coating  3430  is shown as about 90 degrees or less. In some embodiments, the contact angle of the conductive coating  3430  may be greater than about 90 degrees. Referring now to  FIG.  22 B , an embodiment is illustrated wherein the conductive coating  3430  includes a portion extending past the interface between the nucleation inhibiting coating  3420  and the conductive coating  3430 , and is spaced apart from the nucleation inhibiting coating  3420  by a gap  3441 . In such embodiment, for example, the contact angle,  8 , may be greater than about 90 degrees. 
     In at least some applications, it may be particularly advantageous to form a conductive coating  3430  exhibiting a relatively large contact angle. For example, the contact angle may be at least or greater than about 10 degrees, at least or greater than about 15 degrees, at least or greater than about 20 degrees, at least or greater than about 25 degrees, at least or greater than about 30 degrees, at least or greater than about 35 degrees, at least or greater than about 40 degrees, at least or greater than about 50 degrees, at least or greater than about 60 degrees, at least or greater than about 70 degrees, at least or greater than about 75 degrees, or at least or greater than about 80 degrees. For example, conductive coating  3430  having a relatively large contact angle may be particularly advantageous for creating finely patterned features while maintaining a relatively high aspect ratio. In some applications, it may be advantageous to form the conductive coating  3430  exhibiting a contact angle greater than about 90 degrees. For example, the contact angle may be greater than about 90 degrees, at least or greater than about 95 degrees, at least or greater than about 100 degrees, at least or greater than about 105 degrees, at least or greater than about 110 degrees, at least or greater than about 120 degrees, at least or greater than about 130 degrees, at least or greater than about 135 degrees, at least or greater than about 140 degrees, at least or greater than about 145 degrees, at least or greater than about 150 degrees, or at least or greater than about 160 degrees. 
     As described above, it is postulated that a contact angle of a conductive coating is determined based at least partially on the properties (e.g., initial sticking probability) of a nucleation inhibiting coating disposed adjacent to an area onto which the conductive coating is formed. Accordingly, nucleation inhibiting coating materials which allow selective deposition of a conductive coating exhibiting a relatively large contact angle may be particularly useful in certain applications. 
     Without wishing to be bound by a particular theory, it is postulated that the relationship among the various interfacial tensions present during nucleation and growth is dictated according to the following equation, which is also referred to as the Young&#39;s equation in capillarity theory: 
       γ sv =γ fs +cos θ
 
     wherein γ sv  corresponds to the interfacial tension between a substrate and a vapor, γ fs  corresponds to the interfacial tension between a film and the substrate, γ vf  corresponds to the interfacial tension between the vapor and the film, and θ is the film nucleus contact angle.  FIG.  37    illustrates the relationship among the various parameters represented in Young&#39;s equation above. 
     On the basis of Young&#39;s equation, it can be derived that, for island growth, the film nucleus contact angle θ is greater than zero and therefore γ sv &lt;γ fs +γ vf . 
     For layer growth wherein the deposited film “wets” the substrate, the nucleus contact angle θ =0 and therefore γ sv =γ fs +γ vf . 
     For Stranski-Krastanov (S-K) growth, wherein the strain energy per unit area of the film overgrowth is large with respect to the interfacial tension between the vapor and the film, γ sv &gt;γ fs +γ vf . 
       10182 ) It is postulated that the nucleation and growth mode of a conductive coating at an interface between a nucleation inhibiting coating and an exposed substrate surface follows the island growth model, wherein θ&gt;0. Particularly in cases where the nucleation inhibiting coating exhibits a relatively low affinity or low initial sticking probability (e.g., dewetting) towards a material used to form the conductive coating, this low affinity results in a relatively large thin film contact angle of the conductive coating. On the contrary, when a conductive coating is selectively deposited on a surface without the use of a nucleation inhibiting coating, for example, by employing a shadow mask, the nucleation and growth mode of the conductive coating may differ. In particular, it has been observed that the conductive coating formed using a shadow mask patterning process may, at least in some cases, exhibit a relatively small thin film contact angle of less than about 10 degrees. 
     It will be appreciated that, while not explicitly illustrated, a material used to form the nucleation inhibiting coating  3420  may also be present to some extent at an interface between the conductive coating  3430  and an underlying surface (e.g., a surface of the nucleation promoting layer  3451  or the substrate  3410 ). Such material may be deposited as a result of a shadowing effect, in which a deposited pattern is not identical to a pattern of a mask and may result in some evaporated material being deposited on a masked portion of a target surface. For example, such material may form as islands or disconnected clusters, or as a thin film having a thickness that is substantially less than an average thickness of the nucleation inhibiting coating  3420 . 
       FIGS.  22 C and  22 D  illustrate yet other embodiments in which the conductive coating  3430  partially overlaps a portion of the nucleation inhibiting coating  3420  in the third region  3419 , which is disposed between the first region  3415  and the second region  3412 . As illustrated in the figures, the portion of the conductive coating  3430  partially overlapping with a portion of the nucleation inhibiting coating  3420  may be in direct physical contact with the surface  3422  of the nucleation inhibiting coating  3420 . In this regard, the overlap in the third region  3419  may be formed as a result of lateral growth of the conductive coating  3430  during an open mask or mask-free deposition process. More specifically, while the surface  3422  of the nucleation inhibiting coating  3420  may exhibit a relatively low affinity or initial sticking probability for the material of the conductive coating  3430  and thus the probability of the material nucleating on the surface  3422  is low, as the conductive coating  3430  grows in thickness, the coating  3430  may also grow laterally and may cover a portion of the nucleation inhibiting coating  3420 . 
     In the case of  FIGS.  22 C and  22 D , the contact angle θ c  of the conductive coating  3430  may be measured at an edge of the conductive coating  3430  near the interface between the conductive coating  3430  and the nucleation inhibiting coating  3420 , as illustrated in the figures. Particularly with reference to  FIG.  22 D , the contact angle θ c  may be greater than about 90 degrees, which results in a portion of the conductive coating  3430  being spaced apart from the nucleation inhibiting coating  3420  by a gap  3441 . 
     In some embodiments, the nucleation inhibiting coating  3420  may be removed subsequent to deposition of the conductive coating  3430 , such that at least a portion of an underlying surface covered by the nucleation inhibiting coating  3420  in the embodiments of  FIGS.  18 - 22 D  becomes exposed. For example, the nucleation inhibiting coating  3420  may be selectively removed by etching or dissolving the nucleation inhibiting coating  3420 , or using plasma or solvent processing techniques without substantially affecting or eroding the conductive coating  3430 . 
       FIG.  23 A  illustrates a device  5901  according to one embodiment, which includes a substrate  5910  and a nucleation inhibiting coating  5920  and a conductive coating  5915  (e.g., a magnesium coating) deposited over respective regions of a surface of the substrate  5910 . 
       FIG.  23 B  illustrates a device  5902  after the nucleation inhibiting coating  5920  present in the device  5901  has been removed from the surface of the substrate  5910 , such that the conductive coating  5915  remains on the substrate  5910  and regions of the substrate  5910  which were covered by the nucleation inhibiting coating  5920  are now exposed or uncovered. For example, the nucleation inhibiting coating  5920  of the device  5901  may be removed by exposing the substrate  5910  to solvent or plasma which preferentially reacts and/or etches away the nucleation inhibiting coating  5920  without substantially affecting the conductive coating  5915 . 
     A device of some embodiments may be an electronic device, and, more specifically, an opto-electronic device. An opto-electronic device generally encompasses any device that converts electrical signals into photons or vice versa. As such, an organic opto-electronic device can encompass any opto-electronic device where one or more active layers of the device are formed primarily of an organic material, and, more specifically, an organic semiconductor material. Examples of organic opto-electronic devices include, but are not limited to, OLED devices and OPV devices. 
     It will also be appreciated that organic opto-electronic devices may be formed on various types of base substrates. For example, a base substrate may be a flexible or rigid substrate. The base substrate may include, for example, silicon, glass, metal, polymer (e.g., polyimide), sapphire, or other materials suitable for use as the base substrate. 
     It will also be appreciated that various components of a device may be deposited using a wide variety of techniques, including vapor deposition, spin-coating, line coating, printing, and various other deposition techniques. 
     In some embodiments, an organic opto-electronic device is an OLED device, wherein an organic semiconductor layer includes an electroluminescent layer. In some embodiments, the organic semiconductor layer may include additional layers, such as an electron injection layer, an electron transport layer, a hole transport layer, and/or a hole injection layer. For example, the OLED device may be an AMOLED device, PMOLED device, or an OLED lighting panel or module. Furthermore, the opto-electronic device may be a part of an electronic device. For example, the opto-electronic device may be an OLED display module of a computing device, such as a smartphone, a tablet, a laptop, or other electronic device such as a monitor or a television set. 
       FIGS.  24 - 26    illustrate various embodiments of an AMOLED display device. For the sake of simplicity, various details and characteristics of a conductive coating at or near an interface between the conductive coating and a nucleation inhibiting coating described above in reference to  FIGS.  18 - 22 D  have been omitted. However, it will be appreciated that the features described in reference to  FIGS.  18 - 22 D  may also be applicable to the embodiments of  FIGS.  24 - 26   . 
       FIG.  24    is a schematic diagram illustrating a structure of an AMOLED device  3802  according to one embodiment. 
     The device  3802  includes a base substrate  3810 , and a buffer layer  3812  deposited over a surface of the base substrate  3810 . A TFT  3804  is then formed over the buffer layer  3812 . Specifically, a semiconductor active area  3814  is formed over a portion of the buffer layer  3812 , and a gate insulating layer  3816  is deposited to substantially cover the semiconductor active area  3814 . Next, a gate electrode  3818  is formed on top of the gate insulating layer  3816 , and an interlayer insulating layer  3820  is deposited. A source electrode  3824  and a drain electrode  3822  are formed such that they extend through openings formed through the interlayer insulating layer  3820  and the gate insulating layer  3816  to be in contact with the semiconductor active layer  3814 . An insulating layer  3842  is then formed over the TFT  3804 . A first electrode  3844  is then formed over a portion of the insulating layer  3842 . As illustrated in  FIG.  24   , the first electrode  3844  extends through an opening of the insulating layer  3842  such that it is in electrical communication with the drain electrode  3822 . PDLs  3846  are then formed to cover at least a portion of the first electrode  3844 , including its outer edges. For example, the PDLs  3846  may include an insulating organic or inorganic material. An organic layer  3848  is then deposited over the first electrode  3844 , particularly in regions between neighboring PDLs  3846 . A second electrode  3850  is deposited to substantially cover both the organic layer  3848  and the PDLs  3846 . A surface of the second electrode  3850  is then substantially covered with a nucleation promoting coating  3852 . For example, the nucleation promoting coating  3852  may be deposited using an open mask or a mask-free deposition technique. A nucleation inhibiting coating  3854  is selectively deposited over a portion of the nucleation promoting coating  3852 . For example, the nucleation inhibiting coating  3854  may be selectively deposited using a shadow mask. Accordingly, an auxiliary electrode  3856  is selectively deposited over an exposed surface of the nucleation promoting coating  3852  using an open mask or a mask-free deposition process. For further specificity, by conducting thermal deposition of the auxiliary electrode  3856  (e.g., including magnesium) using an open mask or with a mask, the auxiliary electrode  3856  is selectively deposited over the exposed surface of the nucleation promoting coating  3852 , while leaving a surface of the nucleation inhibiting coating  3854  substantially free of a material of the auxiliary electrode  3856 . 
       FIG.  25    illustrates a structure of an AMOLED device  3902  according to another embodiment in which a nucleation promoting coating has been omitted. For example, the nucleation promoting coating may be omitted in cases where a surface on which an auxiliary electrode is deposited has a relatively high initial sticking probability for a material of the auxiliary electrode. In other words, for surfaces with a relatively high initial sticking probability, the nucleation promoting coating may be omitted, and a conductive coating may still be deposited thereon. For sake of simplicity, certain details of a backplane including those regarding the TFT are omitted in describing the following embodiments. 
       101971  In  FIG.  25   , an organic layer  3948  is deposited between a first electrode  3944  and a second electrode  3950 . The organic layer  3948  may partially overlap with portions of PDLs  3946 . A nucleation inhibiting coating  3954  is deposited over a portion (e.g., corresponding to an emissive region) of the second electrode  3950 , thereby providing a surface with a relatively low initial sticking probability (e.g., a relatively low desorption energy) for a material used to form an auxiliary electrode  3956 . Accordingly, the auxiliary electrode  3956  is selectively deposited over a portion of the second electrode  3950  that is exposed from the nucleation inhibiting coating  3954 . As would be understood, the auxiliary electrode  3956  is in electrical communication with the underlying second electrode  3950  so as to reduce a sheet resistance of the second electrode  3950 . For example, the second electrode  3950  and the auxiliary electrode  3956  may include substantially the same material to ensure a high initial sticking probability for the material of the auxiliary electrode  3956 . Specifically, the second electrode  3950  may include substantially pure magnesium (Mg) or an alloy of magnesium and another metal, such as silver (Ag). For Mg:Ag alloy, an alloy composition may range from about 1:9 to about 9:1 by volume. The auxiliary electrode  3956  may include substantially pure magnesium. 
       FIG.  26    illustrates a structure of an AMOLED device  4002  according to yet another embodiment. In the illustrated embodiment, an organic layer  4048  is deposited between a first electrode  4044  and a second electrode  4050  such that it partially overlaps with portions of PDLs  4046 . A nucleation inhibiting coating  4054  is deposited so as to substantially cover a surface of the second electrode  4050 , and a nucleation promoting coating  4052  is selectively deposited on a portion of the nucleation inhibiting coating  4054 . An auxiliary electrode  4056  is then formed over the nucleation promoting coating  4052 . Optionally, a capping layer  4058  may be deposited to cover exposed surfaces of the nucleation inhibiting coating  4054  and the auxiliary electrode  4056 . 
     While the auxiliary electrode  3856  or  4056  is illustrated as not being in direct physical contact with the second electrode  3850  or  4050  in the embodiments of  FIGS.  24  and  26   , it will be understood that the auxiliary electrode  3856  or  4056  and the second electrode  3850  or  4050  may nevertheless be in electrical communication. For example, the presence of a relatively thin film (e.g., up to about 100 nm) of a nucleation promoting material or a nucleation inhibiting material between the auxiliary electrode  3856  or  4056  and the second electrode  3850  or  4050  may still sufficiently allow a current to pass therethrough, thus allowing a sheet resistance of the second electrode  3850  or  4050  to be reduced. 
       FIG.  27    illustrates a structure of an AMOLED device  4102  according to yet another embodiment in which an interface between a nucleation inhibiting coating  4154  and an auxiliary electrode  4156  is formed on a slanted surface created by PDLs  4146 . The device  4102  includes an organic layer  4148  deposited between a first electrode  4144  and a second electrode  4150 , and the nucleation inhibiting coating  4154  is deposited over a portion of the second electrode  4150  which corresponds to an emissive region of the device  4102 . The auxiliary electrode  4156  is deposited over portions of the second electrode  4150  that are exposed from the nucleation inhibiting coating  4154 . 
     While not shown, the AMOLED device  4102  of  FIG.  27    may further include a nucleation promoting coating disposed between the auxiliary electrode  4156  and the second electrode  4150 . The nucleation promoting coating may also be disposed between the nucleation inhibiting coating  4154  and the second electrode  4150 , particularly in cases where the nucleation promoting coating is deposited using an open mask or a mask-free deposition process. 
       FIG.  28 A  illustrates a portion of an AMOLED device  4300  according to yet another embodiment wherein the AMOLED device  4300  includes a plurality of light transmissive regions. As illustrated, the AMOLED device  4300  includes a plurality of pixels  4321  and an auxiliary electrode  4361  disposed between neighboring pixels  4321 . Each pixel  4321  includes a subpixel region  4331 , which further includes a plurality of subpixels  4333 ,  4335 ,  4337 , and a light transmissive region  4351 . For example, the subpixel  4333  may correspond to a red subpixel, the subpixel  4335  may correspond to a green subpixel, and the subpixel  4337  may correspond to a blue subpixel. As will be explained, the light transmissive region  4351  is substantially transparent to allow light to pass through the device  4300 . 
       FIG.  28 B  illustrates a cross-sectional view of the device  4300  taken along line A-A as indicated in  FIG.  28 A . Briefly, the device  4300  includes a base substrate  4310 , a TFT  4308 , an insulating layer  4342 , and an anode  4344  formed on the insulating layer  4342  and in electrical communication with the TFT  4308 . A first PDL  4346   a  and a second PDL  4346   b  are formed over the insulating layer  4342  and cover edges of the anode  4344 . One or more organic layers  4348  are deposited to cover an exposed region of the anode  4344  and portions of the PDLs  4346   a,    4346   b.  A cathode  4350  is then deposited over the one or more organic layers  4348 . Next, a nucleation inhibiting coating  4354  is deposited to cover portions of the device  4300  corresponding to the light transmissive region  4351  and the subpixel region  4331 . The entire device surface is then exposed to magnesium vapor flux, thus causing selective deposition of magnesium over an uncoated region of the cathode  4350 . In this way, the auxiliary electrode  4361 , which is in electrical contact with the underlying cathode  4350 , is formed. 
     In the device  4300 , the light transmissive region  4351  is substantially free of any materials which may substantially affect the transmission of light therethrough. In particular, the TFT  4308 , the anode  4344 , and the auxiliary electrode  4361  are all positioned within the subpixel region  4331  such that these components do not attenuate or impede light from being transmitted through the light transmissive region  4351 . Such arrangement allows a viewer viewing the device  4300  from a typical viewing distance to see through the device  4300  when the pixels are off or are non-emitting, thus creating a transparent AMOLED display. 
     While not shown, the AMOLED device  4300  of  FIG.  28 B  may further include a nucleation promoting coating disposed between the auxiliary electrode  4361  and the cathode  4350 . The nucleation promoting coating may also be disposed between the nucleation inhibiting coating  4354  and the cathode  4350 . 
     In other embodiments, various layers or coatings, including the organic layers  4348  and the cathode  4350 , may cover a portion of the light transmissive region  4351  if such layers or coatings are substantially transparent. Alternatively, the PDLs  4346   a,    4346   b  may not be provided in the light transmissive region  4351 , if desired. 
     It will be appreciated that pixel and subpixel arrangements other than the arrangement illustrated in  FIGS.  28 A and  28 B  may also be used, and the auxiliary electrode  4361  may be provided in other regions of a pixel. For example, the auxiliary electrode  4361  may be provided in the region between the subpixel region  4331  and the light transmissive region  4351 , and/or be provided between neighbouring subpixels, if desired. 
       FIG.  29 A  illustrates a portion of an AMOLED device  4300 ′ according to yet another embodiment wherein the AMOLED device  4300 ′ includes a plurality of light transmissive regions. As illustrated, the AMOLED device  4300 ′ includes a plurality of pixels  4321 ′. Each pixel  4321 ′ includes a subpixel region  4331 ′, which further includes a plurality of subpixels  4333 ′,  4335 ′,  4337 ′, and a light transmissive region  4351 ′. For example, the subpixel  4333 ′ may correspond to a red subpixel, the subpixel  4335 ′ may correspond to a green subpixel, and the subpixel  4337 ′ may correspond to a blue subpixel. As will be explained, the light transmissive region  4351 ′ is substantially transparent to allow light to pass through the device  4300 ′. 
       FIG.  29 B  illustrates a cross-sectional view of the device  4300 ′ taken along line B-B according to one embodiment. The device  4300 ′ includes a base substrate  4310 ′, a TFT  4308 ′, an insulating layer  4342 ′, and an anode  4344 ′ formed on the insulating layer  4342 ′ and in electrical communication with the TFT  4308 ′. A first PDL  4346   a ′ and a second PDL  4346   b ′ are formed over the insulating layer  4342 ′ and cover the edges of the anode  4344 ′. One or more organic layers  4348 ′ are deposited to cover an exposed region of the anode  4344 ′ and portions of the PDLs  4346   a ′,  4346   b ′. A first conductive coating  4350 ′ is then deposited over the one or more organic layers  4348 ′. In the illustrated embodiment, the first conductive coating  4350 ′ is disposed over both the subpixel region  4331 ′ and the light transmissive region  4351 ′. In such embodiment, the first conductive coating  4350 ′ may be substantially transparent or light-transmissive. For example, the thickness of the first conductive coating  4350 ′ may be relatively thin such that the presence of the first conductive coating  4350 ′ does not substantially attenuate transmission of light through the light transmissive region  4351 ′. The first conductive coating  4350 ′ may, for example, be deposited using an open mask or mask-free deposition process. Next, a nucleation inhibiting coating  4362 ′ is deposited to cover portions of the device  4300 ′ corresponding to the light transmissive region  4351 ′. The entire device surface is then exposed to a vapor flux of material for forming the second conductive coating  4352 ′, thus causing selective deposition of the second conductive coating  4352 ′ over an uncoated region of the first conductive coating  4350 ′. Specifically, the second conductive coating  4352 ′ is disposed over a portion of the device  4300 ′ corresponding to the subpixel region  4331 ′. In this way, a cathode for the device  4300 ′ is formed by the combination of the first conductive coating  4350 ′ and the second conductive coating  4352 ′. 
     In some embodiments, the thickness of the first conductive coating  4350 ′ is less than the thickness of the second conductive coating  4352 ′. In this way, relatively high light transmittance may be maintained in the light transmissive region  4351 ′. For example, the thickness of the first conductive coating  4350 ′ may be up to or less than about 30 nm, up to or less than about 25 nm, up to or less than about 20 nm, up to or less than about 15 nm, up to or less than about 10 nm, up to or less than about 8 nm, or up to or less than about 5 nm, and the thickness of the second conductive coating  4352 ′ may be up to or less than about 30 nm, up to or less than about 25 nm, up to or less than about 20 nm, up to or less than about 15 nm, up to or less than about 10 nm, or up to or less than about 8 nm. In other embodiments, the thickness of the first conductive coating  4350 ′ is greater than the thickness of the second conductive coating  4352 ′. In yet another embodiment, the thickness of the first conductive coating  4350 ′ and the thickness of the second conductive coating  4352 ′ may be substantially the same. 
     The material(s) which may be used to form the first conductive coating  4350 ′ and the second conductive coating  4352 ′ may be substantially the same as those used to form conductive coatings in above-described embodiments. Since such materials have been described above in relation to other embodiments, descriptions of these materials are omitted for sake of brevity. 
     In the device  4300 ′, the light transmissive region  4351 ′ is substantially free of any materials which may substantially affect the transmission of light therethrough. In particular, the TFT  4308 ′, the anode  4344 ′, and the conductive coating  4352 ′ are all positioned within the subpixel region  4331  such that these components do not attenuate or impede light from being transmitted through the light transmissive region  4351 ′. Such arrangement allows a viewer viewing the device  4300 ′ from a typical viewing distance to see through the device  4300 ′ when the pixels are off or are non-emitting, thus creating a transparent AMOLED display. 
       FIG.  29 C  illustrates the cross-section of a device  4300 ″ according to another embodiment, wherein a first conductive coating  4350 ″ is selectively disposed in the subpixel region  4331 ′ and the light transmissive region  4351 ′ is substantially free of, or exposed from, the material used to form the first conductive coating  4350 ″. For example, during fabrication of the device  4300 ″, the nucleation inhibiting coating  4362 ′ may be deposited in the light transmissive region  4351 ′ prior to depositing the first conductive coating  4350 ″. In this way, the first conductive coating  4350 ″ may be selectively deposited in the subpixel region  4331 ′ using an open mask or mask-free deposition process. As explained above, the material used to form the first conductive coating  4350 ″ generally exhibits a relatively poor affinity (e.g., low initial sticking probability) towards being deposited onto the surface of the nucleation inhibiting coating  4362 ′. For example, the first conductive coating  4350 ″ may comprise high vapor pressure materials, such as Yb, Zn, Cd and Mg. In some embodiments, the first conductive coating  4350 ″ may comprise pure or substantially pure magnesium. By providing a light transmissive region  4351 ′ that is free or substantially free of the first conductive coating  4350 ″, the light transmittance in such region may be favorably enhanced in some cases, for example in comparison to the device  4300 ′ of  FIG.  29 B . 
     While not shown, the AMOLED device  4300 ′ of  FIG.  29 B  and the AMOLED device  4300 ″ of  FIG.  29 C  may each further include a nucleation promoting coating disposed between the first conductive coating  4350 ′ or  4350 ″ and the underlying surfaces (e.g., the organic layer  4348 ′). Such nucleation promoting coating may also be disposed between the nucleation inhibiting coating  4362 ′ and the underlying surfaces (e.g., the PDLs  4346   a ′- b ′). 
     In some embodiments, the nucleation inhibiting coating  4362 ′ may be formed concurrently with at least one of the organic layers  4348 ′. For example, the material for forming the nucleation inhibiting coating  4362 ′ may also be used to form at least one of the organic layers  4348 ′. In this way, the number of stages for fabricating the device  4300 ′ or  4300 ″ may be reduced. 
     In some embodiments, additional conductive coatings, including the second conductive coating  4352 ′ and a third conductive coating may also be provided over subpixels  4333 ′,  4335 ′, and  4337 ′. Additionally, in some embodiments, an auxiliary electrode may also be provided in non-emissive regions of the device  4300 ′,  4300 ″. For example, such auxiliary electrode may be provided in the regions between neighboring pixels  4321 ′ such that it does not substantially affect the light transmittance in the subpixel regions  4331 ′ or the light transmissive regions  4351 ′. The auxiliary electrode may also be provided in the region between the subpixel region  4331 ′ and the light transmissive region  4351 ′, and/or be provided between neighboring subpixels, if desired. For example, referring to the embodiment of  FIG.  29 B , an additional nucleation inhibiting coating may be deposited over a portion of the second conductive coating  4352 ′ corresponding to the subpixel  4333 ′ region, while leaving a portion corresponding to the non-emissive region uncovered or exposed. In this way, an open mask or mask-free deposition of a conductive material may be conducted to result in an auxiliary electrode being formed over the non-emissive regions of the device  4300 ′. 
     In some embodiments, various layers or coatings, including the organic layers  4348 ′, may cover a portion of the light transmissive region  4351 ′ if such layers or coatings are substantially transparent. Alternatively, the PDLs  4346   a ′,  4346   b ′ may be omitted from the light transmissive region  4351 ′, if desired. 
     It will be appreciated that pixel and subpixel arrangements other than the arrangement illustrated in  FIG.  29 A ,  FIG.  29 B , and  FIG.  29 C  may also be used. 
     In the foregoing embodiments, a nucleation inhibiting coating may, in addition to inhibiting nucleation and deposition of a conductive material (e.g., magnesium) thereon, act to enhance an out-coupling of light from a device. Specifically, the nucleation inhibiting coating may act as an index-matching coating and/or an anti-reflective coating. 
     A barrier coating (not shown) may be provided to encapsulate the devices illustrated in the foregoing embodiments depicting AMOLED display devices. As will be appreciated, such a barrier coating may inhibit various device layers, including organic layers and a cathode which may be prone to oxidation, from being exposed to moisture and ambient air. For example, the barrier coating may be a thin film encapsulation formed by printing, CVD, sputtering, ALD, any combinations of the foregoing, or by any other suitable methods. The barrier coating may also be provided by laminating a pre-formed barrier film onto the devices using an adhesive. For example, the barrier coating may be a multi-layer coating comprising organic materials, inorganic materials, or combination of both. The barrier coating may further comprise a getter material and/or a desiccant in some embodiments. 
     A sheet resistance specification for a common electrode of an AMOLED display device may vary according to a size of the display device (e.g., a panel size) and a tolerance for voltage variation. In general, the sheet resistance specification increases (e.g., a lower sheet resistance is specified) with larger panel sizes and lower tolerances for voltage variation across a panel. 
     The sheet resistance specification and an associated thickness of an auxiliary electrode to comply with the specification according to an embodiment were calculated for various panel sizes. The sheet resistances and the auxiliary electrode thicknesses were calculated for voltage tolerances of 0.1 V and 0.2 V. For the purpose of the calculation, an aperture ratio of 0.64 was assumed for all display panel sizes. 
     The specified thickness of the auxiliary electrode at example panel sizes are summarized in Table 2 below. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Specified thickness of auxiliary  
               
               
                 electrode for various panel sizes 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Panel Size 
                   
                   
                   
                   
                   
                   
               
               
                 (inch) 
                   
                 9.7 
                 12.9 
                 15.4 
                 27 
                 65 
               
               
                   
               
               
                 Specified 
                 @0.1 V 
                 132 
                 239 
                 335 
                 1100 
                 6500 
               
               
                 Thickness 
                   
                   
                   
                   
                   
                   
               
               
                 (nm) 
                 @0.2 V 
                  67 
                 117 
                 174 
                  516 
                 2800 
               
               
                   
               
            
           
         
       
     
     As will be understood, various layers and portions of a backplane, including a TFT (e.g., TFT  3804  shown in  FIG.  24   ) may be fabricated using a variety of suitable materials and processes. For example, the TFT may be fabricated using organic or inorganic materials, which may be deposited and/or processed using techniques such as CVD, PECVD, laser annealing, and PVD (including sputtering). As would be understood, such layers may be patterned using photolithography, which uses a photomask to expose selective portions of a photoresist covering an underlying device layer to UV light. Depending on the type of photoresist used, exposed or unexposed portions of the photomask may then be washed off to reveal desired portion(s) of the underlying device layer. A patterned surface may then be etched, chemically or physically, to effectively remove an exposed portion of the device layer. 
     Furthermore, while a top-gate TFT has been illustrated and described in certain embodiments above, it will be appreciated that other TFT structures may also be used. For example, the TFT may be a bottom-gate TFT. The TFT may be an n-type TFT or a p-type TFT. Examples of TFT structures include those utilizing a-Si, IGZO, and LTPS. 
     Various layers and portions of a frontplane, including electrodes, one or more organic layers, a PDL, and a capping layer may be deposited using any suitable deposition processes, including thermal evaporation and/or printing. It will be appreciated that, for example, a shadow mask may be used as appropriate to produce desired patterns when depositing such materials, and that various etching and selective deposition processes may also be used to pattern various layers. Examples of such methods include, but are not limited to, photolithography, printing (including ink or vapor jet printing and reel-to-reel printing), OVPD, and LITI patterning. 
     Selective Deposition of a Conductive Coating over Emissive Regions 
     In one aspect, a method for selectively depositing a conductive coating over one or more emissive regions is provided. In some embodiments, the method includes depositing a first conductive coating on a substrate. The substrate may include a first emissive region and a second emissive region. The first conductive coating deposited on the substrate may include a first portion coating the first emissive region and a second portion coating the second emissive region of the substrate. The method may further include depositing a first nucleation inhibiting coating on the first portion of the first conductive coating, and then depositing a second conductive coating on the second portion of the first conductive coating. 
       FIG.  30    is a flow diagram outlining stages of manufacturing a device according to one embodiment.  FIGS.  31 A- 31 D  are schematic diagrams illustrating the device at each stage of the process. 
     As illustrated in  FIG.  31 A , a substrate  3102  is provided. The substrate  3102  includes a first emissive region  3112  and a second emissive region  3114 . The substrate  3102  may further include one or more non-emissive regions  3121   a - 3121   c.  For example, the first emissive region  3112  and the second emissive region  3114  may correspond to pixel regions or subpixel regions of an electroluminescent device. 
     In stage  12 , a first conductive coating  3131  is deposited over the substrate. As illustrated in  FIG.  31 B , the first conductive coating  3131  is deposited to coat the first emissive region  3112 , the second emissive region  3114 , and the non-emissive regions  3121   a - 3121   c.  The first conductive coating  3131  includes a first portion  3132  corresponding to the portion coating the first emissive region  3112 , and a second portion  3133  corresponding to the portion coating the second emissive region  3114 . For example, the first conductive coating  3131  may be deposited by evaporation, including thermal evaporation and electron beam evaporation. In some embodiments, the first conductive coating  3131  may be deposited using an open mask or without a mask (e.g., mask-free). The first conductive coating  3131  may be deposited using other methods including, but not limited to, sputtering, chemical vapor deposition, printing (including ink or vapor jet printing, reel-to-reel printing, and micro-contact transfer printing), OVPD, LITI patterning, and combinations thereof. 
     In stage  14 , a first nucleation inhibiting coating  3141  is selectively deposited over a portion of the first conductive coating  3131 . In the embodiment illustrated in  FIG.  31 C , the first nucleation inhibiting coating  3141  is deposited to coat the first portion  3132  of the first conductive coating  3131 , which corresponds to the first emissive region  3112 . In such embodiment, the second portion  3133  of the first conductive coating  3131  disposed over the second emissive region  3114  is substantially free of, or exposed from, the first nucleation inhibiting coating  3141 . In some embodiments, the first nucleation inhibiting coating  3141  may optionally also coat portion(s) of the first conductive coating  3131  deposited over one or more non-emissive regions. For example, the first nucleation inhibiting coating  3141  may optionally also coat the portion(s) of the first conductive coating  3131  deposited over one or more non-emissive regions adjacent to the first emissive region  3112 , such as the non-emissive region  3121   a  and/or  3121   b.  Various processes for selectively depositing a material on a surface may be used to deposit the first nucleation inhibiting coating  3141  including, but not limited to, evaporation (including thermal evaporation and electron beam evaporation), photolithography, printing (including ink or vapor jet printing, reel-to-reel printing, and micro-contact transfer printing), OVPD, LITI patterning, and combinations thereof. 
     Once the first nucleation inhibiting coating  3141  has been deposited on a region of the surface of the first conductive coating  3131 , a second conductive coating  3151  may be deposited on remaining uncovered region(s) of the surface where the nucleation inhibiting coating  3141  is not present. Turning to  FIG.  31 D , in stage  16 , a conductive coating source  3105  is illustrated as directing an evaporated conductive material towards the surfaces of the first conductive coating  3131  and the first nucleation inhibiting coating  3141 . As illustrated in  FIG.  31 D , the conducting coating source  3105  may direct the evaporated conductive material such that it is incident on both covered or treated areas (namely, region(s) of the first conductive coating  3131  with the nucleation inhibiting coating  3141  deposited thereon) and uncovered or untreated areas of the first conductive coating  3131 . However, since a surface of the first nucleation inhibiting coating  3141  exhibits a relatively low initial sticking coefficient compared to that of the uncovered surface of the first conductive coating  3131 , a second conductive coating  3151  selectively deposits onto the areas of the first conductive coating surface where the first nucleation inhibiting coating  3141  is not present. Accordingly, the second conductive coating  3151  may coat the second portion  3133  of the first conductive coating  3131 , which corresponds to the portion of the first conductive coating  3131  coating the second emissive region  3114 . As illustrated in  FIG.  31 D , the second conductive coating  3151  may also coat other portions or regions of the first conductive coating  3131 , including the portions coating the non-emissive regions  3121   a,    3121   b,  and  3121   c.  The second conductive coating  3151  may include, for example, pure or substantially pure magnesium. For example, the second conductive coating  3151  may be formed using materials which are identical to those used to form the first conductive coating  3131 . The second conductive coating  3151  may be deposited using an open mask or without a mask (e.g., mask-free deposition process). 
     In some embodiments, the method may further include additional stages following stage  16 . Such additional stages may include, for example, depositing one or more additional nucleation inhibiting coatings, depositing one or more additional conductive coatings, depositing an auxiliary electrode, depositing an outcoupling coating, and/or encapsulation of the device. 
     It will be appreciated that, while the method has been illustrated and described above in relation to a device having the first and second emissive regions, it can similarly be applied to devices having three or more emissive regions. For example, such method may be used to deposit a conductive coating of varying thickness according to the emission spectrum of each of the emissive regions. 
     The first conductive coating  3131  and the second conductive coating  3151  may be light transmissive or substantially transparent in at least a portion of the visible wavelength range of the electromagnetic spectrum. For further clarity, the first conductive coating  3131  and the second conductive coating  3151  may each be light transmissive or substantially transparent in at least a portion of the visible wavelength range of the electromagnetic spectrum. Thus when the second conductive coating  3151  (and any additional conductive coating) is disposed on top of the first conductive coating  3131  to form a multi-coating electrode, such electrode may also be light transmissive or substantially transparent in the visible wavelength portion of the electromagnetic spectrum. For example, the light transmittance of the first conductive coating  3131 , the second conductive coating  3151 , and/or the multi-coating electrode may be at least or greater than about 30%, at least or greater than about 40%, at least or greater than about 45%, at least or greater than about 50%, at least or greater than about 60%, at least or greater than 70%, at least or greater than about 75%, or at least or greater than about 80% in a visible portion of the electromagnetic spectrum. 
     In some embodiments, the thickness of the first conductive coating  3131  and the second conductive coating  3151  may be made relatively thin to maintain a relatively high light transmittance. For example, the thickness of the first conductive coating  3131  may be about 5 nm to about 30 nm, about 8 nm to about 25 nm, or about 10 nm to about 20 nm. The thickness of the second conductive coating  3151  may, for example, be about 1 nm to about 25 nm, about 1 nm to about 20 nm, about 1 nm to about 15 nm, about 1 nm to about 10 nm, or about 3 nm to about 6 nm. Accordingly, the thickness of a multi-coating electrode formed by the combination of the first conductive coating  3131 , the second conductive coating  3151  and any additional conductive coating may, for example, be about 6 nm to about 35 nm, about 10 nm to about 30 nm, about 10 nm to about 25 nm, or about 12 nm to about 18 nm. 
     The first emissive region  3112  and the second emissive region  3114  may correspond to subpixel regions of an OLED display device in some embodiments. Accordingly, it will be appreciated that the substrate  3102  onto which various coatings are deposited may include one or more additional organic and/or inorganic layers not specifically illustrated or described in the foregoing embodiments. For example, the OLED display device may be an AMOLED display device. In such embodiments, the substrate  3102  may include an electrode and at least one organic layer deposited over the electrode in each emissive region (e.g., subpixel), such that the first conductive coating  3131  may be deposited over the at least one organic layer. For example, the electrode may be an anode, and the first conductive coating  3131 , either by itself or in combination with the second conductive coating  3151  and any additional conductive coatings, may form a cathode. The at least one organic layer may include an emitter layer. The at least one organic layer may further include a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, and/or any additional layers. The substrate  3102  may further include a plurality of TFTs. Each anode provided in the device may be electrically connected to at least one TFT. For example, the substrate  3102  may include one or more top-gate TFTs, one or more bottom-gate TFTs, and/or other TFT structures. A TFT may be an n-type TFT or a p-type TFT. Examples of TFT structures include those including a-Si, IGZO, and LTPS. 
     The substrate  3102  may also include a base substrate for supporting the above-identified additional organic and/or inorganic layers. For example, the base substrate may be a flexible or rigid substrate. The base substrate may include, for example, silicon, glass, metal, polymer (e.g., polyimide), sapphire, or other materials suitable for use as the base substrate. 
     The first emissive region  3112  and the second emissive region  3114  may be subpixels configured to emit light of different wavelength or emission spectrum from one another. The first emissive region  3112  may be configured to emit light having a first wavelength or first emission spectrum, and the second emissive region  3114  may be configured to emit light having a second wavelength or second emission spectrum. The first wavelength may be less than or greater than the second wavelength. The device may include any number of additional emissive regions, pixels, or subpixels. For instance, the device may include additional emissive regions which are configured to emit light having a third wavelength or third emissive spectrum, which is different from the wavelength or emissive spectrum of the first emissive region  3112  or the second emissive region  3114 . The device may also include additional emissive regions which are configured to emit light having substantially identical wavelength or emissive spectrum as the first emissive region  3112 , the second emissive region  3114 , or other additional emissive regions. 
     In some embodiments, the first nucleation inhibiting coating  3141  may be selectively deposited using the same shadow mask used to deposit the at least one organic layer of the first emissive region  3112 . In this way, an optical microcavity effect may be tuned for each subpixel in a cost-effective manner due to there being no additional mask requirements for depositing the nucleation inhibiting coating  3141 . 
       FIG.  32    is a schematic cross-sectional diagram illustrating a portion of an AMOLED device  1300 . For sake of simplicity, certain details of a backplane including those regarding the TFTs  1308   a,    1308   b,    1308   c  are omitted in describing the following embodiments. 
     In the embodiment of  FIG.  32   , the device  1300  includes a first emissive region  1331   a,  a second emissive region  1331   b,  and a third emissive region  1331   c.  For example, the emissive regions may correspond to the subpixels of the device  1300 . In the device  1300 , a first electrode  1344   a,    1344   b,    1344   c  is formed in each of the first emissive region  1331   a,  the second emissive region  1331   b,  and the third emissive region  1331   c,  respectively. As illustrated in  FIG.  32   , each of the first electrode  1344   a,    1344   b,    1344   c  extends through an opening of an insulating layer  1342  such that it is in electrical communication with the respective TFTs  1308   a,    1308   b.    1308   c.  PDLs  1346   a - d  are then formed to cover at least a portion of the first electrodes  1344   a - c , including the outer edges of each electrode. For example, the PDLs  1346   a - d  may include an insulating organic or inorganic material. An organic layer  1348   a,    1348   b,    1348   c  is then deposited over the respective first electrode  1344   a,    1344   b,    1344   c,  particularly in regions between neighboring PDLs  1346   a - d . A first conductive coating  1371  is deposited to substantially cover both the organic layers  1348   a - d  and the PDLs  1346   a - d . For example, the first conductive coating  1371  may form a common cathode, or a portion thereof. A first nucleation inhibiting coating  1361  is selectively deposited over a portion of the first conductive coating  1371  disposed over the first emissive region  1331   a.  For example, the first nucleation inhibiting coating  1361  may be selectively deposited using a fine metal mask or a shadow mask. Accordingly, a second conductive coating  1372  is selectively deposited over an exposed surface of the first conductive coating  1371  using an open mask or a mask-free deposition process. For further specificity, by conducting thermal deposition of the second conductive coating  1372  (e.g., including magnesium) using an open mask or without a mask, the second conductive coating  1372  is selectively deposited over the exposed surface of the first conductive coating  1371 , while leaving a surface of the first nucleation inhibiting coating  1361  substantially free of a material of the first conductive coating  1372 . The second conductive coating  1372  may be deposited to coat the portions of the first conductive coating  1371  disposed over the second emissive region  1331   b  and the third emissive region  1331   c.    
     In the device  1300  illustrated in  FIG.  32   , the first conductive coating  1371  and the second conductive coating  1372  may collectively form a common cathode  1375 . Specifically, the common cathode  1375  may be formed by the combination of the first conductive coating  1371  and the second conductive coating  1372 , wherein the second conductive coating  1372  is disposed directly over at least a portion of the first conductive coating  1371 . The common cathode  1375  has a first thickness t c1  in the first emissive region  1331   a,  and a second thickness t c2  in the second emissive region  1335   b  and the third emissive region  1335   c.  The first thickness t c1  may correspond to the thickness of the first conductive coating  1371 , and the second thickness tc 2  may correspond to the combined thickness of the first conductive coating  1371  and the second conductive coating  1372 . Accordingly, the second thickness tc 2  is greater than the first thickness t c1 . 
       FIG.  33    illustrates a further embodiment of the device  1300  wherein the common cathode  1375  further includes a third conductive coating  1373 . Specifically in the embodiment of  FIG.  33   , the device  1300  includes a second nucleation inhibiting coating  1362  disposed over a portion of the second conductive coating  1372  provided over the second emissive region  1331   b . A third conductive coating  1373  is then deposited over the exposed or untreated surface(s) of the second conductive coating  1372 , including the portion of the second conductive coating  1372  disposed over the third emissive region  1331   c.  In this way, a common cathode  1375  having a first thickness t c1  in the first emissive region  1331   a,  a second thickness tc 2  in the second emissive region  1331   b,  and a third thickness t c3  in the third emissive region  1331   c  may be provided. As would be appreciated, the first thickness t c1  corresponds to the thickness of the first conductive coating  1371 , the second thickness tc 2  corresponds to the combined thickness of the first conductive coating  1371  and the second conductive coating  1372 , and the third thickness t c3  corresponds to the combined thickness of the first conductive coating  1371 , the second conductive coating  1372 , and the third conductive coating  1373 . Accordingly, the first thickness t c1  may be less than the second thickness tc 2 , and the third thickness t c3  may be greater than the second thickness t c2 . 
     In yet another embodiment illustrated in  FIG.  34   , the device  1300  may further include a third nucleation inhibiting coating  1363  disposed over the third emissive region  1331   c.  Specifically, the third nucleation inhibiting coating  1363  is illustrated as being deposited over a portion of the third conductive coating  1373  coating a portion of the device  1300  corresponding to the third emissive region  1331   c.    
     In yet another embodiment illustrated in  FIG.  35   , the device  1300  further includes an auxiliary electrode  1381  disposed in the non-emissive regions of the device  1300 . For example, the auxiliary electrode  1381  may be formed using substantially the same processes as those used to deposit the second conductive coating  1372  and/or the third conductive coating  1373 . The auxiliary electrode  1381  is illustrated as being deposited over the PDLs  1346   a -1346 d,  which correspond to the non-emissive regions of the device  1300 . The emissive regions  1331   a,    1331   b,    1331   c  may be substantially free of the material used to form the auxiliary electrode  1381 . 
     The first conductive coating  1371 , the second conductive coating  1372 , and the third conductive coating  1373  may be light transmissive or substantially transparent in the visible wavelength portion of the electromagnetic spectrum. For further clarity, the first conductive coating  1371 , the second conductive coating  1372 , and the third conductive coating  1373  may each be light transmissive or substantially transparent at least in a portion of the visible wavelength range of the electromagnetic spectrum. Thus, when the second conductive coating  1372  and/or the third conductive coating  1373  are disposed on top of the first conductive coating  1371  to form the common cathode  1375 , such electrode may also be light transmissive or substantially transparent in the visible wavelength portion of the electromagnetic spectrum. For example, the light transmittance of the first conductive coating  1371 , the second conductive coating  1372 , the third conductive coating  1373 , and/or the common cathode  1375  may be at least or greater than about 30%, at least or greater than about 40%, at least or greater than about 45%, at least or greater than about 50%, at least or greater than about 60%, at least or greater than 70%, at least or greater than about 75%, or at least or greater than about 80% in a visible portion of the electromagnetic spectrum. 
     In some embodiments, the thickness of the first conductive coating  1371 , the second conductive coating  1372 , and the third conductive coating  1373  may be made relatively thin to maintain a relatively high light transmittance. For example, the thickness of the first conductive coating  1371  may be about 5 nm to about 30 nm, about 8 nm to about 25 nm, or about 10 nm to about 20 nm. The thickness of the second conductive coating  1372  may, for example, be about 1 nm to about 25 nm, about 1 nm to about 20 nm, about 1 nm to about 15 nm, about 1 nm to about 10 nm, or about 3 nm to about 6 nm. The thickness of the third conductive coating  1373  may, for example, be about 1 nm to about 25 nm, about 1 nm to about 20 nm, about 1 nm to about 15 nm, about 1 nm to about 10 nm, or about 3 nm to about 6 nm. Accordingly, the thickness of a common cathode  1375  formed by the combination of the first conductive coating  1371  and the second conductive coating  1372  and/or the third conductive coating  1373  may, for example, be about 6 nm to about 35 nm, about 10 nm to about 30 nm, or about 10 nm to about 25 nm, or about 12 nm to about 18 nm. 
     The thickness of the auxiliary electrode  1381  may be greater than the thickness of the first conductive coating  1371 , the second conductive coating  1372 , the third conductive coating  1373 , and/or the common cathode  1375 . For example, the thickness of the auxiliary electrode  1381  may be at least or greater than about 50 nm, at least or greater than about 80 nm, at least or greater than about 100 nm, at least or greater than about 150 nm, at least or greater than about 200 nm, at least or greater than about 300 nm, at least or greater than about 400 nm, at least or greater than about 500 nm, at least or greater than about 700 nm, at least or greater than about 800 nm, at least or greater than about 1 μm, at least or greater than about 1.2 μm, at least or greater than about 1.5 μm, at least or greater than about 2 μm, at least or greater than about 2.5 μm, or at least or greater than about 3 μm. In some embodiments, the auxiliary electrode  1381  may be substantially non-transparent or opaque. However, since the auxiliary electrode  1381  is generally provided in the non-emissive region(s) of the device  1300 , the auxiliary electrode  1381  may not cause significant optical interference. For example, the light transmittance of the auxiliary electrode  1381  may be less than about 50%, less than about 70%, less than about 80%, less than about 85%, less than about 90%, or less than about 95% in the visible portion of the electromagnetic spectrum. In some embodiments, the auxiliary electrode  1381  may absorb light in at least a portion of the visible wavelength range of the electromagnetic spectrum. 
     The first conductive coating  1371  may include various materials suitably used to form light transmissive conductive layers or coatings. For example, the first conductive coating  1371  may include TCOs, metallic or non-metallic thin films, and any combination thereof. The first conductive coating  1371  may further include two or more layers or coatings. For example, such layers or coatings may be distinct layers or coatings disposed on top of one another. The first conductive coating  1371  may include various materials including, for example, ITO, fluorine tin oxide (FTO), Mg, Al, Yb, Ag, Zn, Cd and any combinations thereof, including alloys containing any of the foregoing materials. For example, the first conductive coating  1371  may include a Mg:Ag alloy, a Mg:Yb alloy, or a combination thereof. For a Mg:Ag alloy or a Mg:Yb alloy, the alloy composition may range from about 1:9 to about 9:1 by volume. 
     The second conductive coating  1372  and the third conductive coating  1373  may include high vapor pressure materials, such as Yb, Zn, Cd and Mg. In some embodiments, the second conductive coating  1372  and the third conductive coating  1373  may include pure or substantially pure magnesium. 
     The auxiliary electrode  1381  may include substantially the same material(s) as the second conductive coating  1372  and/or the third conductive coating  1373 . In some embodiments, the auxiliary electrode  1381  may include magnesium. For example, the auxiliary electrode  1381  may include pure or substantially pure magnesium. In other examples, the auxiliary electrode  1381  may include Yb, Cd, and/or Zn. 
     In some embodiments, the thickness of the nucleation inhibiting coating  1361 ,  1362 ,  1363  disposed in the emissive regions  1331   a,    1331   b,    1331   c  may be varied according to the color or emission spectrum of the light emitted by each emissive region. As illustrated in  FIGS.  34 - 35   , the first nucleation inhibiting coating  1361  may have a first nucleation inhibiting coating thickness t n1 , the second nucleation inhibiting coating  1362  may have a second nucleation inhibiting coating thickness t n2 , and the third nucleation inhibiting coating  1363  may have a third nucleation inhibiting coating thickness t n3 . The first nucleation inhibiting coating thickness hit, the second nucleation inhibiting coating thickness t n2 , and/or the third nucleation inhibiting coating thickness t n3  may be substantially the same as one another. Alternatively, the first nucleation inhibiting coating thickness t n1 , the second nucleation inhibiting coating thickness t n2 , and/or the third nucleation inhibiting coating thickness tn 3  may be different from one another. 
     By modulating the thickness of a nucleation inhibiting coating disposed in each emissive region or subpixel independently of one another, optical microcavity effects in each emissive region or subpixel can be further controlled. For example, the thickness of the nucleation inhibiting coating disposed over a blue subpixel may be less than the thickness of the nucleation inhibiting coating disposed over a green subpixel, and the thickness of the nucleation inhibiting coating disposed over a green subpixel may be less than the thickness of the nucleation inhibiting coating disposed over a red subpixel. As would be appreciated, the optical microcavity effect in each emissive region or subpixel may be controlled to an even greater extent by modulating both the nucleation inhibiting coating thickness and the conductive coating thickness for each emissive region or subpixel independent of other emissive regions or subpixels. 
     Optical microcavity effects arise due to the presence of optical interfaces created by numerous thin-film layers and coatings with different refractive indices, which are used to construct opto-electronic devices such as OLEDs. Some factors which affect the optical microcavity effect observed in a device include the total path length (e.g., the total thickness of the device through which light emitted from the device travels before being out-coupled) and the refractive indices of various layers and coatings. It has now been found that, by modulating the thickness of a cathode in an emissive region (e.g., subpixel), the optical microcavity effect in the emissive region may be varied. Such effect may generally be attributed to the change in the total optical path length. It is further postulated that, particularly in the case of light-transmissive cathode formed by thin coating(s), the change in the cathode thickness may also change the refractive index of the cathode in addition to the total optical path length. Furthermore, the optical path length, and thus the optical microcavity effect, may also be modulated by changing the thickness of a nucleation inhibiting coating disposed in the emissive region. 
     The optical properties of a device which may be affected by modulating the optical microcavity effects include the emission spectrum, intensity (e.g., luminous intensity), and angular distribution of the output light, including the angular dependence of the brightness and color shift of the output light. 
     While various embodiments have been described with 2 or 3 emissive regions or subpixels, it will be appreciated devices may include any number of emissive regions or subpixels. For example, a device may include a plurality of pixels, wherein each pixel includes 2, 3, or more subpixels. Furthermore, the specific arrangement of the pixels or subpixels with respect to other pixels or subpixels may be varied depending on the device design. For example, the subpixels may be arranged according to suitable arrangement schemes such as RGB side-by-side, diamond, or PenTile®. 
     Selective Deposition of Optical Coating 
     In one aspect according to some embodiments, a device is provided. The device may be an opto-electronic device. In some embodiments, the device includes a substrate, a nucleation inhibiting coating, and an optical coating. The nucleation inhibiting coating covers a first region of the substrate. The optical coating covers a second region of the substrate, and at least a portion of the nucleation inhibiting coating is exposed from, or is substantially free of or is substantially uncovered by, the optical coating. 
     The optical coating may be used to modulate optical properties of light being transmitted, emitted, or absorbed by the device, including plasmon modes. For example, the optical coating may be used as an optical filter, index-matching coating, optical out-coupling coating, scattering layer, diffraction grating, or portions thereof. In another example, the optical coating may be used to modulate the microcavity effects in an opto-electronic device by tuning, for example, the total optical path length and/or the refractive index. The optical properties of the device which may be affected by modulating the optical microcavity effects include the emission spectrum, intensity (e.g., luminous intensity), and angular distribution of the output light, including the angular dependence of the brightness and color shift of the output light. In some embodiments, the optical coating may be a non-electrical component. In other words, the optical coating may not be configured to conduct or transmit electrical current during normal device operation in such embodiments. 
     For example, the optical coating may be formed using any of the various embodiments of methods for depositing a conductive coating described above. The optical coating may include high vapor pressure materials, such as Yb, Zn, Cd and Mg. In some embodiments, the optical coating may include pure or substantially pure magnesium. 
     Thin Film Formation 
     The formation of thin films during vapor deposition on a surface of a substrate involves processes of nucleation and growth. During initial stages of film formation, a sufficient number of vapor monomers (e.g., atoms or molecules) typically condense from a vapor phase to form initial nuclei on the surface. As vapor monomers continue to impinge upon the surface, a size and density of these initial nuclei increase to form small clusters or islands. After reaching a saturation island density, adjacent islands typically will start to coalesce, increasing an average island size, while decreasing an island density. Coalescence of adjacent islands continues until a substantially closed film is formed. 
     There can be three basic growth modes for the formation of thin films: 1) island (Volmer-Weber), 2) layer-by-layer (Frank-van der Merwe), and 3) Stranski-Krastanov. Island growth typically occurs when stable clusters of monomers nucleate on a surface and grow to form discrete islands. This growth mode occurs when the interactions between the monomers is stronger than that between the monomers and the surface. 
     The nucleation rate describes how many nuclei of a critical size form on a surface per unit time. During initial stages of film formation, it is unlikely that nuclei will grow from direct impingement of monomers on the surface, since the density of nuclei is low, and thus the nuclei cover a relatively small fraction of the surface (e.g., there are large gaps/spaces between neighboring nuclei). Therefore, the rate at which critical nuclei grow typically depends on the rate at which adsorbed monomers (e.g., adatoms) on the surface migrate and attach to nearby nuclei. 
     After adsorption of an adatom on a surface, the adatom may either desorb from the surface, or may migrate some distance on the surface before either desorbing, interacting with other adatoms to form a small cluster, or attach to a growing nuclei. An average amount of time that an adatom remains on the surface after initial adsorption is given by: 
     
       
         
           
             
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     In the above equation, v is a vibrational frequency of the adatom on the surface, k is the Boltzmann constant, T is temperature, and E des  is an energy involved to desorb the adatom from the surface. From this equation it is noted that the lower the value of E des  the easier it is for the adatom to desorb from the surface, and hence the shorter the time the adatom will remain on the surface. A mean distance an adatom can diffuse is given by, 
     
       
         
           
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     where a 0  is a lattice constant and E s  is an activation energy for surface diffusion. For low values of E des  and/or high values of E s  the adatom will diffuse a shorter distance before desorbing, and hence is less likely to attach to a growing nuclei or interact with another adatom or cluster of adatoms. 
     During initial stages of film formation, adsorbed adatoms may interact to form clusters, with a critical concentration of clusters per unit area being given by, 
     
       
         
           
             
               
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     where E i  is an energy involved to dissociate a critical cluster containing i adatoms into separate adatoms, n 0  is a total density of adsorption sites, and N 1  is a monomer density given by: 
       N 1 ={dot over (R)}τ s  
 
     where {dot over (R)} is a vapor impingement rate. Typically i will depend on a crystal structure of a material being deposited and will determine the critical cluster size to form a stable nucleus. 
     A critical monomer supply rate for growing clusters is given by the rate of vapor impingement and an average area over which an adatom can diffuse before desorbing: 
     
       
         
           
             
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     The critical nucleation rate is thus given by the combination of the above equations: 
     
       
         
           
             
               
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     From the above equation it is noted that the critical nucleation rate will be suppressed for surfaces that have a low desorption energy for adsorbed adatoms, a high activation energy for diffusion of an adatom, are at high temperatures, or are subjected to low vapor impingement rates. 
     Sites of substrate heterogeneities, such as defects, ledges or step edges, may increase E des , leading to a higher density of nuclei observed at such sites. Also, impurities or contamination on a surface may also increase E des , leading to a higher density of nuclei. For vapor deposition processes conducted under high vacuum conditions, the type and density of contaminates on a surface are affected by a vacuum pressure and a composition of residual gases that make up that pressure. 
     Under high vacuum conditions, a flux of molecules that impinge on a surface (per cm 2 -sec) is given by: 
     
       
         
           
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     where P is pressure, and M is molecular weight. Therefore, a higher partial pressure of a reactive gas, such as H 2 O, can lead to a higher density of contamination on a surface during vapor deposition, leading to an increase in E des  and hence a higher density of nuclei. 
       102751  A useful parameter for characterizing nucleation and growth of thin films is the sticking probability given by: 
     
       
         
           
             S 
             = 
             
               
                 N 
                 ads 
               
               
                 N 
                 total 
               
             
           
         
       
     
     where N ads  is a number of adsorbed monomers that remain on a surface (e.g., are incorporated into a film) and N total  is a total number of impinging monomers on the surface. A sticking probability equal to 1 indicates that all monomers that impinge the surface are adsorbed and subsequently incorporated into a growing film. A sticking probability equal to 0 indicates that all monomers that impinge the surface are desorbed and subsequently no film is formed on the surface. A sticking probability of metals on various surfaces can be evaluated using various techniques of measuring the sticking probability, such as a dual quartz crystal microbalance (QCM) technique as described by Walker et al., J. Phys. Chem. C 2007, 111, 765 (2006). 
     As the density of islands increases (e.g., increasing average film thickness), a sticking probability may change. For example, a low initial sticking probability may increase with increasing average film thickness. This can be understood based on a difference in sticking probability between an area of a surface with no islands (bare substrate) and an area with a high density of islands. For example, a monomer that impinges a surface of an island may have a sticking probability close to 1. 
     An initial sticking probability So can therefore be specified as a sticking probability of a surface prior to the formation of any significant number of critical nuclei. One measure of an initial sticking probability can involve a sticking probability of a surface for a material during an initial stage of deposition of the material, where an average thickness of the deposited material across the surface is at or below a threshold value. In the description of some embodiments, a threshold value for an initial sticking probability can be specified as 1 nm. An average sticking probability is then given by: 
           S =S   0 (1− A   nuc )+ S   nuc ( A   nuc )
 
     where S nuc  is a sticking probability of an area covered by islands, and A nuc  is a percentage of an area of a substrate surface covered by islands. 
     An example of an energy profile of an adatom adsorbed onto a substrate surface is illustrated in  FIG.  38   . Specifically,  FIG.  38    illustrates the energy profiles corresponding to: (1) an adatom escaping from a local low energy site; (2) diffusion of the adatom on the surface; and (3) desorption of the adatom. 
     In (1), the local low energy site may be any site on the substrate surface onto which the adatom will be at a lower energy. Typically, the nucleation site may be a defect or anomaly on the surface substrate, such as for example, step edges, chemical impurities, bonding sites, or kinks. Once the adatom is trapped at the local low energy site, there is typically an energy barrier before surface diffusion can take place. This energy barrier is represented as ΔE in the diagram of  FIG.  38   . If the energy barrier to escape the local low energy site is large enough, the site may act as a nucleation site. 
     In (2), the adatom may diffuse on the substrate surface. For example, in the case of localized absorbates, the adatom tends to oscillate near the minima of the surface potential and migrates to various neighboring sites until the adatom is either desorbed, or is incorporated into a growing film or growing islands formed by a cluster of adatoms. In the diagram of  FIG.  38   , the activation energy associated with surface diffusion of the adatom is represented as E s . 
     In (3), the activation energy associated with desorption of the adatom from the surface is represented as E des . It will be appreciated that any adatoms that are not desorbed would remain on the substrate surface. For example, such adatoms may diffuse on the surface, be incorporated as part of a growing film or coating, or become part of a cluster of adatoms that form islands on the surface. 
     Based on energy profile shown in  FIG.  38   , it can be postulated that nucleation inhibiting coating materials exhibiting a relatively low activation energy for desorption (E des ) and/or a relatively high activation energy for surface diffusion (E s ) may be particularly advantageous for use in various applications. For example, it may be particularly advantageous in some embodiments for the activation energy for desorption (E des ) to be less than about 2 times the thermal energy (k B T), less than about 1.5 times the thermal energy, less than about 1.3 times the thermal energy, less than about 1.2 times the thermal energy, less than the thermal energy, less than about 0.8 times the thermal energy, or less than about 0.5 times the thermal energy. In some embodiments, it may be particularly advantageous for the activation energy for surface diffusion (E s ) to be greater than the thermal energy, greater than about 1.5 times the thermal energy, greater than about 1.8 times the thermal energy, greater than about 2 times the thermal energy, greater than about 3 times the thermal energy, greater than about 5 times the thermal energy, greater than about 7 times the thermal energy, or greater than about 10 times the thermal energy. 
     While certain embodiments have been described above with reference to selectively depositing a conductive coating to form a cathode or an auxiliary electrode for a common cathode, it will be understood that similar materials and processes may be used to form an anode or an auxiliary electrode for an anode in other embodiments. 
     Nucleation Inhibiting Coating 
     Suitable materials for use to form a nucleation inhibiting coating include those exhibiting or characterized as having an initial sticking probability for a material of a conductive coating of no greater than or less than about 0.1 (or 10%) or no greater than or less than about 0.05, and, more particularly, no greater than or less than about 0.03, no greater than or less than about 0.02, no greater than or less than about 0.01, no greater than or less than about 0.08, no greater than or less than about 0.005, no greater than or less than about 0.003, no greater than or less than about 0.001, no greater than or less than about 0.0008, no greater than or less than about 0.0005, or no greater than or less than about 0.0001. Suitable materials for use to form a nucleation promoting coating include those exhibiting or characterized as having an initial sticking probability for a material of a conductive coating of at least about 0.6 (or 60%), at least about 0.7, at least about 0.75, at least about 0.8, at least about 0.9, at least about 0.93, at least about 0.95, at least about 0.98, or at least about 0.99. 
     Examples of nucleation inhibiting coatings suitable for use in at least in some applications include, but are not limited to, those formed by depositing PBD, PBD2, mCP, TAZ, β-NPB, NTAZ, tBUP-TAZ, BND, TBADN, CBP, BAlq, m-BPC, Ir(ppy) 3 , or combination thereof. 
     Suitable nucleation inhibiting materials include organic materials, such as small molecule organic materials and organic polymers. Examples of suitable organic materials include polycyclic aromatic compounds including organic molecules which may optionally include one or more heteroatoms, such as nitrogen (N), sulfur (S), oxygen (O), phosphorus (P), and aluminum (Al). In some embodiments, a polycyclic aromatic compound includes organic molecules each including a core moiety and at least one terminal moiety bonded to the core moiety. A number of terminal moieties may be 1 or more, 2 or more, 3 or more, or 4 or more. In the case of 2 or more terminal moieties, the terminal moieties may be the same or different, or a subset of the terminal moieties may be the same but different from at least one remaining terminal moiety. In some embodiments, at least one terminal moiety is, or includes, a biphenylyl moiety represented by one of the chemical structures (I-a), (I-b), and (Ic) as follows: 
     
       
         
         
             
             
         
       
     
     wherein the dotted line indicates a bond formed between the biphenylyl moiety and the core moiety. In general, the biphenylyl moiety represented by (I-a), (I-b) and (I-c) may be unsubstituted or may be substituted by having one or more of its hydrogen atoms replaced by one or more substituent groups. In the moiety represented by (I-a), (I-b), and (I-c), R a  and R b  independently represent the optional presence of one or more substituent groups, wherein Ra may represent mono, di, tri, or tetra substitution, and Rb may represent mono, di, tri, tetra, or penta substitution. For example, one or more substituent groups, Ra and Rb, may independently be selected from: deutero, fluoro, alkyl including C 1 -C 4  alkyl, cycloalkyl, arylalkyl, silyl, aryl, heteroaryl, fluoroalkyl, and any combinations thereof. Particularly, one or more substituent groups, R a  and R b , may be independently selected from: methyl, ethyl, t-butyl, trifluoromethyl, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, t-butylphenyl, biphenylyl, methylbiphenylyl, dimethylbiphenylyl, trimethylbiphenylyl, t-butylbiphenylyl, fluorophenyl, difluorophenyl, trifluorophenyl, polyfluorophenyl, fluorobiphenylyl, difluorobiphenylyl, trifluorobiphenylyl, and polyfluorobiphenylyl. Without wishing to be bound by a particular theory, the presence of an exposed biphenylyl moiety on a surface may serve to adjust or tune a surface energy (e.g., a desorption energy) to lower an affinity of the surface towards deposition of a conductive material such as magnesium. Other moieties and materials that yield a similar tuning of a surface energy to inhibit deposition of magnesium may be used to form a nucleation inhibiting coating. 
     In another embodiment, at least one terminal moiety is, or includes, a phenyl moiety represented by the structure (I-d) as follows: 
     
       
         
         
             
             
         
       
     
     wherein the dotted line indicates a bond formed between the phenyl moiety and the core moiety. In general, the phenyl moiety represented by (I-d) may be unsubstituted or may be substituted by having one or more of its hydrogen atoms replaced by one or more substituent groups. In the moiety represented by (I-d), Itc represents the optional presence of one or more substituent groups, wherein R c  may represent mono, di, tri, tetra, or penta substitution. One or more substituent groups, R c , may be independently selected from: deutero, fluoro, alkyl including C 1 -C 4  alkyl, cycloalkyl, silyl, fluoroalkyl, and any combinations thereof. Particularly, one or more substituent groups, R c , may be independently selected from: methyl, ethyl, t-butyl, fluoromethyl, bifluoromethyl, trifluoromethyl, fluoroethyl, and polyfluoroethyl. 
     In yet another embodiment, at least one terminal moiety is, or includes, a tert-butylphenyl moiety represented by one of the structures (I-e), (I-f), or (I-g) as follows: 
     
       
         
         
             
             
         
       
     
     wherein the dotted line indicates a bond formed between the t-butylphenyl moiety and the core moiety. In general, the t-butylphenyl moiety represented by (I-e), (I-f) and (I-g) may be unsubstituted or may be substituted by having one or more of its hydrogen atoms replaced by one or more substituent groups. In the moiety represented by (I-e), (I-f) and (I-g), R f  represents the optional presence of one or more substituent groups, wherein R f  may represent mono, di, tri, or tetra substitution. For example, one or more substituent groups, R f , may independently be selected from: deutero, fluoro, alkyl including C 1 -C 4  alkyl, cycloalkyl, arylalkyl, silyl, aryl, heteroaryl, fluoroalkyl, and any combinations thereof. Particularly, one or more substituent groups, R f , may be independently selected from: methyl, ethyl, t-butyl, trifluoromethyl, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, t-butylphenyl, biphenylyl, methylbiphenylyl, dimethylbiphenylyl, trimethylbiphenylyl, t-butylbiphenylyl, fluorophenyl, difluorophenyl, trifluorophenyl, polyfluorophenyl, fluorobiphenylyl, difluorobiphenylyl, trifluorobiphenylyl, and polyfluorobiphenylyl. In addition to the above, any of the methyl groups of the t-butyl group may optionally be substituted by deuterated methyl or fluorine. Without wishing to be bound by any particular theory, it is postulated that, among the t-butylphenyl moieties (I-e), (I-f) and (I-g) shown above, the structure (I-e) may be particularly desirable in some applications. It is further postulated that the structure (I-e), in which the t-butyl group is substituted onto the phenyl moiety in the para position, is generally more readily synthesized in comparison to structures (I-f) and (I-g) due to the t-butyl group experiencing the least steric hindrance caused by the presence of the core and other terminal moieties which may be present during synthesis paths. 
     In yet another embodiment, at least one terminal moiety is, or includes, a moiety represented by the structure (I-h) as follows: 
     
       
         
         
             
             
         
       
     
     wherein X 11  to X 15  and X 21  to X 25  are independently selected from C (including CH) or N. In some embodiments, a bond, including a covalent bond or a dative bond for example, may be formed between any one of X 11  to X 15  and the core moiety. In other embodiments, a bond, including a covalent bond or a dative bond for example, may be formed between any one of X 21  to X 25  and the core moiety. In yet another embodiment, a bond may be formed between any one of X 11  to X 15  and the core moiety, and an additional bond may be formed between any one of X 21  to X 25  and the core moiety. For example, in the case of complexes such as metal complexes, two or more bonds may be formed between the moiety (I-h) and the core moiety. In general, the moiety represented by (I-h) may be unsubstituted or may be substituted by having one or more of its hydrogen atoms replaced by one or more substituent groups. In the moiety represented by (I-h), R d  and R e  independently represent the optional presence of one or more substituent groups, wherein R d  may represent mono, di, tri, tetra, or penta substitution, and R e  may represent mono, di, tri, tetra, or penta substitution. For example, one or more substituent groups, R d  and R e , may independently be selected from: deutero, fluoro, alkyl including C 1 -C 4  alkyl, cycloalkyl, arylalkyl, silyl, aryl, heteroaryl, fluoroalkyl, and any combinations thereof. Particularly, one or more sub stituent groups, R d  and R e , may be independently selected from: methyl, ethyl, t-butyl, trifluoromethyl, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, t-butylphenyl, biphenylyl, methylbiphenylyl, dimethylbiphenylyl, trimethylbiphenylyl, t-butylbiphenylyl, fluorophenyl, difluorophenyl, trifluorophenyl, polyfluorophenyl, fluorobiphenylyl, difluorobiphenylyl, trifluorobiphenylyl, and polyfluorobiphenylyl. 
     In yet another embodiment, at least one terminal moiety is, or includes, a polycyclic aromatic moiety including fused ring structures, such as fluorene moieties or phenylene moieties (including those containing multiple (e.g., 3, 4, or more) fused benzene rings). Examples of such moieties include spirobifluorene moiety, triphenylene moiety, diphenylfluorene moiety, dimethylfluorene moiety, difluorofluorene moiety, and any combinations thereof. 
     In some embodiments, a polycyclic aromatic compound includes organic molecules represented by at least one of chemical structures (II), (III), and (IV) as follows: 
     
       
         
         
             
             
         
       
     
     In (II), (III), and (IV), C represents a core moiety, and T 1 , T 2 , and T 3  represent terminal moieties bonded to the core moiety. Although 1, 2, and 3 terminal moieties are depicted in (II), (III), and (IV), it should be understood that more than 3 terminal moieties also may be included. 
     In some embodiments, C is, or includes, a heterocyclic moiety, such as a heterocyclic moiety including one or more nitrogen atoms, for which an example is a triazole moiety. In some embodiments, C is, or includes, a metal atom (including transition and post-transition atoms), such as an aluminum atom, a copper atom, an iridium atom, and/or a platinum atom. In some embodiments, C is, or includes, a nitrogen atom, an oxygen atom, and/or a phosphorus atom. In some embodiments, C is, or includes, a cyclic hydrocarbon moiety, which may be aromatic. In some embodiments, C is, or includes, a substituted or unsubstituted alkyl, which may be branched or unbranched, a cycloalkynyl (including those containing between 1 and 7 carbon atoms), an alkenyl, an alkynyl, an aryl (including phenyl, naphthyl, thienyl, and indolyl), an arylalkyl, a heterocyclic moiety (including cyclic amines such as morpholino, piperdino and pyrolidino), a cyclic ether moiety (such as tetrahydrofuran and tetrahydropyran moieties), a heteroaryl (including pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyrimidine, polycyclic heteroaromatic moieties, and dibenzylthiophenyl), fluorene moieties, silyl, and any combinations thereof. In some embodiments, C is, or includes a complex, such as a metal coordination complex. Examples of such complexes are described further below. In such embodiments, for example, the one or more terminal moieties may be bonded to one or more ligands that surround the complex center. 
     In (II), (III), and (IV), T 1  is, or includes, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above. The moiety, T 1 , may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. Examples of a linker moiety include —O— (where O denotes an oxygen atom), —S— (where S denotes a sulfur atom), and cyclic or acyclic hydrocarbon moieties including 1, 2, 3, 4, or more carbon atoms, and which may be unsubstituted or substituted, and which may optionally include one or more heteroatoms. The bond between the core moiety and one or more terminal moieties may be a covalent bond or a bond formed between a metallic element and an organic element, particularly in the case of organometallic compounds. 
     In (III), T 1  and T 2  may be the same or different, as long as at least T 1  is, or includes, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above. For example, each of T 1  and T 2  may be, or may include, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h) or a polycyclic aromatic moiety including fused ring structures as described above. As another example, T 1  is, or includes, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above, while T 2  may lack such a moiety. In some embodiments, T 2  is, or includes, a cyclic hydrocarbon moiety, which may be aromatic, which may include a single ring structure or may be polycyclic, which may be substituted or unsubstituted, and which may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. In some embodiments, T 2  is, or includes, a heterocyclic moiety, such as a heterocyclic moiety including one or more nitrogen atoms, which may include a single ring structure or may be polycyclic, which may be substituted or unsubstituted, and which may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. In some embodiments, T 2  is, or includes, an acyclic hydrocarbon moiety, which may be unsubstituted or substituted, which may optionally include one or more heteroatoms, and which may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. In some embodiments where T 1  and T 2  are different, T 2  may be selected from moieties having sizes comparable to T 1 . Specifically, T 2  may be selected from the above-listed moieties having molecular weights no greater than about 2 times, no greater than about 1.9 times, no greater than about 1.7 times, no greater than about 1.5 times, no greater than about 1.2 times, or no greater than about 1.1 times a molecular weight of T 1 . Without wishing to be bound by a particular theory, it is postulated that, when the terminal moiety T 2  is included which is different from or lacks a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above, a comparable size of T 2  with respect to T 1  may promote exposure of T 1  on a surface, in contrast to bulky terminal groups that may hinder exposure of T 1  due to molecular stacking, steric hindrance, or a combination of such effects. 
     In (IV), T 1 , T 2 , and T 3  may be the same or different, as long as at least T 1  is, or includes, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above. For example, each of T 1 , T 2 , and T 3  may be, or may include, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above. As another example, each of T 1  and T 2  may be, or may include, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above, while T 3  may lack such a moiety. As another example, each of T 1  and T 3  may be, or may include, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above, while T 2  may lack such a moiety. As a further example, T 1  is, or includes, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above, while both T 2  and T 3  may lack such a moiety. In some embodiments, at least one T 2  and T 3  is, or includes, a cyclic hydrocarbon moiety, which may be aromatic, which may include a single ring structure or may be polycyclic, which may be substituted or unsubstituted, and which may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. In some embodiments, at least one T 2  and T 3  is, or includes, a heterocyclic moiety, such as a heterocyclic moiety including one or more nitrogen atoms, which may include a single ring structure or may be polycyclic, which may be substituted or unsubstituted, and which may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. In some embodiments, at least one T 2  and T 3  is, or includes, an acyclic hydrocarbon moiety, which may be unsubstituted or substituted, which may optionally include one or more heteroatoms, and which may be directly bonded to the core moiety, or may be bonded to the core moiety via a linker moiety. In some embodiments where T 1 , T 2 , and T 3  are different, T 2  and T 3  may be selected from moieties having sizes comparable to T 1 . Specifically, Ta and T 3  may be selected from the above-listed moieties having molecular weights no greater than about 2 times, no greater than about 1.9 times, no greater than about 1.7 times, no greater than about 1.5 times, no greater than about 1.2 times, or no greater than about 1.1 times a molecular weight of T 1 . Without wishing to be bound by a particular theory, it is postulated that, when the terminal moieties T 2  and T 3  are included which are different from or lacks a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above, a comparable size of T 2  and T 3  with respect to T 1  may promote exposure of T 1  on a surface, in contrast to bulky terminal groups that may hinder exposure of T 1  due to molecular stacking, steric hindrance, or a combination of such effects. 
     Suitable nucleation inhibiting materials include polymeric materials. Examples of such polymeric materials include: fluoropolymers, including but not limited to perfluorinated polymers and polytetrafluoroethylene (PTFE); polyvinylbiphenyl; polyvinylcarbazole (PVK); and polymers formed by polymerizing a plurality of the polycyclic aromatic compounds as described above. In another example, polymeric materials include polymers formed by polymerizing a plurality of monomers, wherein at least one of the monomers includes a terminal moiety that is, or includes, a moiety represented by (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), or (I-h), or a polycyclic aromatic moiety including fused ring structures as described above. 
     Suitable nucleation inhibiting materials also include complexes, such as organo-metallic complexes or metal coordination complexes. Examples of such complexes include those formed by a metallic coordination center and ligands surrounding the coordination center. Examples of an atom or ion which may form the coordination center include, but are not limited to, iridium (Ir), Zn, rhodium (Rh), Al, beryllium (Be), rhenium (Re), ruthenium (Ru), boron (B), P, Cu, osmium (Os), gold (Au), and platinum (Pt). In complexes or metal coordination complexes, a dative bond may be formed between the coordination center and one or more atoms of the surrounding ligands. Examples of bonds which may be formed between the coordination center and one or more atoms of the surrounding ligands include, but are not limited to, those formed between a metallic atom of the coordination center and carbon, nitrogen, or oxygen. Specifically, examples of such bonds include those formed between Al and O, Al and N, Zn and O, Zn and N, Zn and C, Be and O, Be and N, Ir and N, Ir and C, Ir and O, Cu and N, B and C, Pt and N, Pt and O, Os and N, Ru and N, Re and N, Re and O, Re and C, Cu and P, Au and N, and Os and C. 
     An example of a ligand which may be present in a metal coordination complex includes a phenylpyridine ligand, which is illustrated below as being bonded to a coordination center, M. 
     
       
         
         
             
             
         
       
     
     For example, M may be a metal center such as Ir. It will be appreciated that such complex may include one or more phenylpyridine ligands. For example, 1, 2, or 3 phenylpyridine ligands may be bonded to the coordination center, M. In other examples, the complex may include other ligands in addition to one or more phenylpyridine ligands. 
     EXAMPLES 
     Aspects of some embodiments will now be illustrated and described with reference to the following examples, which are not intended to limit the scope of the present disclosure in any way. 
     As used in the examples herein, a reference to a layer thickness of a material refers to an amount of the material deposited on a target surface (or target region(s) of the surface in the case of selective deposition), which corresponds to an amount of the material to cover the target surface with an uniformly thick layer of the material having the layer thickness. By way of example, depositing a layer thickness of 10 nm indicates that an amount of the material deposited on the surface corresponds to an amount of the material to form an uniformly thick layer of the material that is 10 nm thick. It will be appreciated that, for example, due to possible stacking or clustering of molecules or atoms, an actual thickness of the deposited material may be non-uniform. For example, depositing a layer thickness of 10 nm may yield some portions of the deposited material having an actual thickness greater than 10 nm, or other portions of the deposited material having an actual thickness less than 10 nm. A certain layer thickness of a material deposited on a surface can correspond to an average thickness of the deposited material across the surface. 
     Molecular structures of certain materials used in the illustrative examples are provided below. 
     
       
         
         
             
             
         
       
     
     As used herein, TAZ refers to 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole, Liq refers to 8-hydroxy-quinolinato lithium, BAlq refers to Bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminum, HT 211  refers to N-[1,1′-Biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine, LG201 refers to 2-(4-(9,10-Di(naphthalen-2-yl)anthracene-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole, PBD refers to 2-(4-tent-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole, PBD2 refers to 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole, mCP refers to 1,3-Bis(N-carbazolyl)benzene. NPB 
     Example 1 
     In order to characterize an effect of using various materials to form a nucleation inhibiting coating, a series of samples were prepared using different materials to form the nucleation inhibiting coating. 
     Specifically, the samples were fabricated by depositing a nucleation inhibiting coating having various thicknesses over a glass substrate, followed by open mask deposition of magnesium. An average evaporation rate of about 2 Å/s was used to deposit a magnesium coating for each of the samples. In conducting the deposition of the magnesium coating, a deposition time of about 5000 seconds was used in order to obtain a reference layer thickness of magnesium of about 1 μm. 
     Once the samples were fabricated, optical transmission measurements were taken to determine the relative amount of magnesium deposited on the surface of the nucleation inhibiting coating. As will be appreciated, relatively thin magnesium coatings having, for example, thickness of less than 10 nm are substantially transparent. However, light transmission decreases as the thickness of the magnesium coating is increased. Accordingly, the relative performance of various nucleation inhibiting coating materials may be assessed by measuring the light transmission through the samples, which directly correlates to the amount or thickness of magnesium coating deposited thereon from the magnesium deposition process. The thickness of the nucleation inhibiting coating and the optical transmission measurement for each sample is summarized in Table 3 below. In calculating the optical transmission measurement, any loss or absorption of light caused by the presence of the glass substrate and the nucleation inhibiting coating was subtracted from the measured transmittance. As such, the optical transmission value provided in Table 3 reflects solely the transmission of light (taken at a wavelength of about 550 nm) through any magnesium coating which may be present on the surface of the nucleation inhibiting coating. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Table of Optical Transmission Measurement Data 
               
            
           
           
               
               
               
            
               
                 Nucleation Inhibiting  
                 Nucleation Inhibiting 
                 Optical  
               
               
                 Coating Material 
                 Coating Thickness (nm) 
                 Transmission (%) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 PBD 
                 29 
                 92 
               
               
                 PBD2 
                 56 
                 100 
               
               
                 mCP 
                 31 
                 98 
               
               
                 LG201 
                 200 
                 5 
               
               
                 TAX 
                 18 
                 100 
               
               
                 β- NPB 
                 63 
                 99 
               
               
                 NTAZ 
                 50 
                 100 
               
               
                 Liq 
                 27 
                 23 
               
               
                 tBup- TAZ 
                 43 
                 100 
               
               
                 BND 
                 24 
                 100 
               
               
                 TBADN 
                 66 
                 99 
               
               
                 CBP 
                 33 
                 100 
               
               
                 HT211 
                 32 
                 5 
               
               
                 BAIq 
                 58 
                 95 
               
               
                 M-BPC 
                 15 
                 100 
               
               
                 Ir(ppy) 
                 9 
                 96 
               
               
                   
               
            
           
         
       
     
     Based on the above, it can be seen that relatively high optical transmission of above 90% was measured for samples fabricated using PBD, PBD 2 , mCP, TAZ, β-NPB, NTAZ, tBUP-TAZ, BND, TBADN, CBP, BAlq, m-BPC, or Ir(ppy)3 as the nucleation inhibiting coating material. As explained above, high optical transmission can be directly attributed to a relatively small amount of magnesium coating, if any, being present on the surface of the nucleation inhibiting coating to absorb the light being transmitted through the sample. Accordingly, these nucleation inhibiting coating materials generally exhibit relatively low affinity or initial sticking probability to magnesium and thus may be particularly useful for achieving selective deposition and patterning of magnesium coating in certain applications. 
     On the other hand, samples fabricated using LG201, Liq, and HT211 exhibited relatively low optical transmission. In particular, the sample fabricated using Liq exhibited a relatively low optical transmission of less than about 25%, and the samples fabricated using LG201 and HT211 exhibited even lower optical transmission of about 5%. This is indicative of a relatively large amount or thick layer of magnesium coating being deposited on the surface of the coating of these materials, which results in significant absorption of light. Accordingly, these materials generally exhibit relatively high affinity or initial sticking probability and thus may be undesirable for use in achieving selective deposition of magnesium coating, particularly in applications specifying selective deposition of a relatively thick magnesium coating of several hundred nanometers, a micron, or more. 
     As used in this and other examples described herein, a reference layer thickness refers to a layer thickness of magnesium that is deposited on a reference surface exhibiting a high initial sticking coefficient (e.g., a surface with an initial sticking coefficient of about or close to 1.0). Specifically for these examples, the reference surface was a surface of a quartz crystal positioned inside a deposition chamber for monitoring a deposition rate and the reference layer thickness. In other words, the reference layer thickness does not indicate an actual thickness of magnesium deposited on a target surface (e.g., a surface of the nucleation inhibiting coating). Rather, the reference layer thickness refers to the layer thickness of magnesium that would be deposited on the reference surface upon subjecting the target surface and reference surface to identical magnesium vapor flux for the same deposition period (e.g., the surface of the quartz crystal). As would be appreciated, in the event that the target surface and reference surface are not subjected to identical vapor flux simultaneously during deposition, an appropriate tooling factor may be used to determine and monitor the reference layer thickness. 
     Example 2 
     In order to determine what effects a magnesium evaporation rate may have on the nucleation inhibiting properties of various materials, a series of samples were prepared using different materials to form a nucleation inhibiting coating and then exposed to relatively high magnesium vapor flux. 
     Specifically, the samples were fabricated by depositing a nucleation inhibiting coating having various thicknesses over a glass substrate, followed by open mask evaporation of magnesium over the nucleation inhibiting coating. The samples were subjected to a magnesium flux having an average deposition rate of about 10 Å/s, as measured using the reference surface. In conducting the deposition of the magnesium coating, a deposition time of about 1000 seconds was used in order to obtain a reference layer thickness of magnesium of about 1 μm. 
     Once the samples were fabricated, optical transmission measurements were taken to determine the relative amount of magnesium deposited on the surface of the nucleation inhibiting coating. The thickness of the nucleation inhibiting coating and the optical transmission measurement for each sample is summarized in Table 4 below. In calculating the optical transmission measurement, any loss or absorption of light caused by the presence of the glass substrate and the nucleation inhibiting coating was subtracted from the measured transmittance. As such, the optical transmission value provided in Table 4 reflects solely the transmission of light (taken at a wavelength of about 550 nm) through any magnesium coating which may be present on the surface of the nucleation inhibiting coating. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Table of Optical Transmission Measurement Data 
               
            
           
           
               
               
               
            
               
                 Nucleation Inhibiting 
                 Nucleation Inhibiting  
                 Optical  
               
               
                 Coating Material 
                 Coating Thickness (nm) 
                 Transmission (%) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 PBD 
                 50 
                 8 
               
               
                 mCP 
                 66 
                 72 
               
               
                 TAZ 
                 33 
                 100 
               
               
                 β-NPB 
                 25 
                 0 
               
               
                 NTAZ 
                 50 
                 98 
               
               
                 tBuP-TAZ 
                 52 
                 100 
               
               
                 CBP 
                 45 
                 20 
               
               
                 BAIq 
                 47 
                 94 
               
               
                   
               
            
           
         
       
     
     Based on the above, it can be seen that relatively high optical transmission of above 90% was measured for samples fabricated using TAZ, NTAZ, tBuP-TAZ, or BAlq as the nucleation inhibiting coating material. As explained above, high optical transmission can be directly attributed to a relatively small amount of magnesium coating, if any, being present on the surface of the nucleation inhibiting coating. Accordingly, these nucleation inhibiting coating materials may be particularly useful for achieving selective deposition and patterning of magnesium coating in certain applications. For example, these materials may be particularly suitable for applications in which the deposition rate of magnesium coating is higher than about 2 Å/s. 
     The sample fabricated using mCP as the nucleation inhibiting coating material exhibited optical transmission of about 72%. While it is generally more favorable to use a material exhibiting higher optical transmission and thus superior nucleation inhibiting properties (e.g., low initial sticking probability) for applications specifying highly selective deposition of magnesium coating, materials such as mCP may nevertheless be useful in forming the nucleation inhibiting coating for certain applications. 
       103241  Samples fabricated using PBD, f 3 -NPB, and CBP all exhibited relatively low optical transmission. In particular, the sample fabricated using CBP exhibited a relatively low optical transmission of about 20%, and the samples fabricated using PBD and β-NPB exhibited even lower optical transmission of about 8% and 0%, respectively. This is indicative of a relatively large amount or thick layer of magnesium coating being deposited on the surface of the nucleation inhibiting coating, which results in significant absorption of light. Accordingly, these materials may be less desirable for use in achieving selective deposition of magnesium coating, particularly in applications specifying selective deposition of a relatively thick magnesium coating at a high deposition rate greater than about 2 Å/s (e.g., deposition rate of about 10 Å/s). 
     By comparing the results of Example 2 to those of Example 1, it has been determined, somewhat surprisingly, that some materials substantially inhibit deposition of magnesium thereon when subjected to magnesium vapor flux at a relatively low deposition rate or evaporation rate, but the degree to which magnesium deposition is inhibited is substantially decreased when a relatively high deposition rate or evaporation rate of magnesium is used. In other words, it has been observed that selective deposition of magnesium coating may be successfully achieved using certain nucleation inhibiting coating materials (such as, for example, PBD, β-NPB, and CBP) at a relatively low magnesium deposition rate of about 2 Å/s. However, at a relatively high deposition rate of about 10 Å/s, highly selective deposition of magnesium coating could be less adequately achieved using the same nucleation inhibiting coating materials. 
     It has also been observed that some nucleation inhibiting coating materials appear to be effective at inhibiting deposition of magnesium thereon, irrespective of the magnesium deposition rate used in these examples. Based on the experimental results, materials such as TAZ, NTAZ, tBuP-TAZ, and BAlq may be used to form an effective nucleation inhibiting coating for achieving highly selective deposition of magnesium coating at magnesium deposition rate of at least up to about 10 Å/s or greater. 
     Without wishing to be bound by a particular theory, it is postulated, based on the theory of nucleation and growth discussed above, that surfaces formed by depositing materials such as TAZ, NTAZ, tBuP-TAZ, and BAlq generally exhibit a relatively low desorption energy (E des ) for adsorbed magnesium adatoms, a high activation energy (E s ) for diffusion of magnesium adatoms, or both. In this way, the critical nucleation rate ({dot over (N)} i ), which is determined according to the equation below, remains relatively low even when the vapor impingement rate of magnesium (P) is increased, thus substantially inhibiting deposition of magnesium. 
     
       
         
           
             
               
                 N 
                 . 
               
               i 
             
             = 
             
               
                 R 
                 . 
               
               ⁢ 
               
                 a 
                 0 
                 2 
               
               ⁢ 
               
                 
                   
                     n 
                     0 
                   
                   ( 
                   
                     R 
                     
                       vn 
                       0 
                     
                   
                   ) 
                 
                 i 
               
               ⁢ 
               
                 exp 
                 ⁡ 
                 ( 
                 
                   
                     
                       
                         ( 
                         
                           i 
                           + 
                           1 
                         
                         ) 
                       
                       ⁢ 
                       
                         E 
                         des 
                       
                     
                     - 
                     
                       E 
                       S 
                     
                     + 
                     
                       E 
                       i 
                     
                   
                   kT 
                 
                 ) 
               
             
           
         
       
     
     In addition, it can readily be observed, based on the equation above, that the critical nucleation rate is increased at higher vapor impingement rate. Accordingly, nucleation inhibiting coatings formed by materials such as LG201, Liq, and HT211, which were found to lack sufficient selectivity even at relatively low magnesium deposition rate of 2 Å/s based on the results of Example 1, would be expected to exhibit even lower selectivity when higher magnesium deposition rate is used. 
     It is postulated that the temperature of the substrate may be increased when the vapor impingement rate (e.g., the evaporation rate) is increased. For example, the evaporation source is typically operated at a higher temperature when the evaporation rate is increased. Accordingly, at higher evaporation rate, the substrate may be subjected to higher level of thermal radiation, which can heat up the substrate. Other factors, which may result in increased substrate temperature, include heating of the substrate caused by energy transfer from greater number of evaporated molecules being incident on the substrate surface, as well as increased rate of condensation or desublimation of molecules on the substrate surface releasing energy in the process and causing heating. 
     For further clarity, the term “selectivity” when used in the context of a nucleation inhibiting coating should be understood to refer to the degree to which the nucleation inhibiting coating inhibits or prevents deposition of a conductive coating thereon, upon being subjected to a vapor flux of a material used to form the conductive coating. For example, a nucleation inhibiting coating exhibiting a relatively high selectivity for magnesium would generally better inhibit or prevent deposition of magnesium coating thereon compared to a nucleation inhibiting coating having a relatively low selectivity. In general, it has been observed that a nucleation inhibiting coating exhibiting a relatively high selectivity would also exhibit a relatively low initial sticking probability, and a nucleation inhibiting coating exhibiting a relatively low selectivity would exhibit a relatively high initial sticking probability. 
     Example 3 
     A series of samples were fabricated to analyze the features and characteristics of a conductive coating at or near an interface between the conductive coating and a nucleation inhibiting coating. 
     Specifically, each sample was prepared by depositing an about 30 nm thick coating of substantially pure silver (Ag) over a silicon substrate. A nucleation inhibiting coating was then deposited over a portion of the silver-coated substrate surface, such that a portion of the silver-coated substrate surface remained exposed, or substantially free of the nucleation inhibiting coating. Once the nucleation inhibiting coating was deposited, substantially pure magnesium (about 99.99% purity) was deposited using an open mask deposition, such that both the exposed silver-coated substrate surface and the nucleation inhibiting coating surface were subjected to an evaporated magnesium flux during the open mask deposition. All depositions were conducted under vacuum (about 10 −4  Pa to about 10 −6  Pa). The magnesium coating was deposited by evaporation, using a deposition rate of about 2 Å/s. 
       FIG.  36 A  is an SEM micrograph showing a portion of the sample fabricated using CBP as the nucleation inhibiting coating material. 
       FIG.  36 B  is an SEM micrograph showing a portion of the sample fabricated using mCP as the nucleation inhibiting coating material. 
       FIG.  36 C  is an SEM micrograph showing a portion of the sample fabricated using TAZ as the nucleation inhibiting coating material. 
       FIG.  36 D  is an SEM micrograph showing a portion of the sample fabricated using BAlq as the nucleation inhibiting coating material. 
       FIG.  36 E  is an SEM micrograph showing a portion of the sample fabricated using tBuP-TAZ as the nucleation inhibiting coating material. 
       FIG.  36 F  is an SEM micrograph showing a portion of the sample fabricated using PBD as the nucleation inhibiting coating material. 
     In each of  FIGS.  36 A- 36 F , the conductive coating  3011  is deposited on a portion of the silicon base substrate  3001 . The portion of the silicon base substrate  3001  that has been treated by depositing the nucleation inhibiting coating is indicated using the reference numeral  3021 . 
     For reference, a comparative sample was prepared to determine a profile of a magnesium coating deposited on a surface using a shadow mask technique. 
     The comparative sample was fabricated by depositing about 30 nm layer thickness of silver on top of a silicon wafer, followed by shadow mask deposition of about 800 nm layer thickness of magnesium. Specifically, the shadow mask deposition was configured to allow certain regions of the silver surface to be exposed to a magnesium flux through a shadow mask aperture while masking other regions of the silver surface. Magnesium was deposited at a rate of about 2 Å/s. 
       FIG.  36 G  is a top view of an SEM image of the comparative sample. An approximate interface is shown using a dotted line in  FIG.  36 G . A first region  5203  corresponds to the masked region, and a second region  5201  corresponds to the exposed region over which a magnesium coating was deposited. 
       FIG.  36 H  is a cross-sectional SEM image of the comparative sample. As can be seen in  FIG.  36 H , the magnesium coating deposited over the second region  5201  includes a relatively long (about 6 μm) “tail” portion  5214  where the thickness of the portion  5214  gradually decreases. It is observed that the tail portion  5214  extends for approximately 6 μm or more in the sample of  FIGS.  36 G and  36 H , which may be undesirable for certain applications specifying selective patterning of fine features or features of relatively high aspect ratio. 
     Example 4 
     In one example, a fine mesh mask having a plurality of apertures was used to demonstrate selective deposition of a metallic coating including magnesium at high resolution. 
     A substrate was prepared by depositing an approximately 20 nm thick silver coating on its surface. The fine mesh mask was then used to selectively deposit a nucleation inhibiting coating including TAZ over portions of the silver-coated surface. Specifically, during deposition of the nucleation inhibiting coating, the fine mesh mask was positioned immediately adjacent to the silver-coated surface, such that portions of the evaporated nucleation inhibiting material flux were selectively transmitted through the apertures of the fine mesh mask to be deposited onto the silver-coated surface. In this way, multiple regions covered by the nucleation inhibiting coating were formed over the silver-coated surface. Each region covered a square area of approximately 7 μm in width, and neighboring regions were separated by a distance of approximately 5.5 μ.m from one another. The thickness of the nucleation inhibiting coating was approximately 50 nm, and was deposited at approximately 0.16 angstroms/s.  FIG.  40 A  is an SEM micrograph showing an example region covered with the nucleation inhibiting coating.  FIG.  40 B  is an Auger electron spectroscopy plot showing the spectra corresponding to carbon and silver, which were obtained from scanning the area surrounding the region covered by the nucleation inhibiting coating. 
     The substrate treated with the nucleation inhibiting coating was then subjected to an evaporated magnesium flux through an open mask, such that the evaporated magnesium was incident on both the regions covered by the nucleation inhibiting coating and the silver-coated surface.  FIG.  41 A  is an SEM micrograph showing a portion of the sample following the deposition of magnesium. The thickness of the magnesium coating was approximately 500 nm.  FIG.  41 B  is an Auger electron spectroscopy plot showing the spectra corresponding to carbon and magnesium, which were obtained from conducting a linear scan across the imaged area of  FIG.  41 A . 
     As can be seen based on  FIGS.  41 A and  41 B , at least the majority of the region covered by the nucleation inhibiting coating remained substantially free of, or exposed from, the magnesium coating. It was observed, however, that the size of the area which is substantially free of, or exposed from, the magnesium coating may, at least in some cases, be smaller than the size of the region over which the nucleation inhibiting coating is provided. It is postulated that this is due to the lateral growth of the magnesium coating causing formation of an “overhang” feature which partially overlaps or extends above the nucleation inhibiting coating, particularly at or near the interface between the nucleation inhibiting coating and the magnesium coating. Specifically, it can be observed that the approximate size of the region that is substantially free of magnesium in the example of  FIGS.  41 A and  41 B  is about 5.5 μm in width. 
     This is further shown in SEM micrographs of  FIGS.  42 A and  43 A , which show the region between neighboring regions coated by the nucleation inhibiting coating, before and after the sample was subjected to magnesium deposition, respectively. As can be seen, the edge-to-edge distance between neighboring regions coated by the nucleation inhibiting coating was approximately 5.5 μm in  FIG.  42 A , while the edge-to-edge distance between the neighboring regions which are substantially free from the magnesium coating in  FIG.  43 A  was found to be approximately 6.4 μm.  FIGS.  42 B and  43 B  are Auger electron spectroscopy plots taken from areas corresponding to the images of  FIGS.  42 A and  43 A , respectively. 
     Example 5 
     A series of kinetic Monte Carlo (KMC) calculations were conducted to simulate the deposition of metallic adatoms on surfaces exhibiting various activation energies. Specifically, the calculations were conducted to simulate the deposition of metallic adatoms, such as magnesium adatoms, on surfaces having varying activation energy levels associated with desorption (E des ), diffusion (E s ), dissociation (E i ), and reaction to the surface (E b ) by subjecting such surfaces to evaporated vapor flux at a constant rate of monomer flux.  FIG.  39    is a schematic illustration of the various “events” taken into consideration for the current example. In  FIG.  39   , an atom  5301  in the vapor phase is illustrated as being incident onto a surface  5300 . Once the atom  5301  is adsorbed onto the surface  5300 , it becomes an adatom  5303 . The adatom  5303  may undergo various events including: (i) desorption, upon which a desorbed atom  5311  is created; (ii) diffusion, which gives rise to an adatom  5313  diffusing on the surface  5300 ; (iii) nucleation, in which a critical number of adatoms  5315  cluster to form a nucleus; and (iv) reaction to the surface, in which an adatom  5317  is reacted and becomes bound to the surface  5300 . 
     The rate (R) at which desorption, diffusion, or dissociation occurs is calculated from the frequency of attempt (Ω), activation energy of the respective event (E), the Boltzmann constant (k B ), and the temperature of the system (T), in accordance with the equation provided below: 
     
       
         
           
             R 
             = 
             
               ω 
               ⁢ 
               
                 exp 
                 ⁡ 
                 ( 
                 
                   
                     - 
                     E 
                   
                   
                     
                       k 
                       B 
                     
                     ⁢ 
                     T 
                   
                 
                 ) 
               
             
           
         
       
     
     For the purpose of the above calculations, i, the critical cluster size (e.g., critical number of adatoms to form a stable nucleus) was selected to be 2. The activation energy of diffusion for adatom-adatom interaction was selected to be greater than about 0.6 eV, the activation energy of desorption for adatom-adatom interaction was selected to be greater than about 1.5 eV, and the activation energy of desorption for adatom-adatom interaction was selected to be greater than about 1.25 times the activation energy of desorption for surface-adatom interaction. The above values and conditions were selected based on the values reported for magnesium-magnesium interactions. For the purpose of the simulations, a temperature (T) of 300 K was used. The calculations were repeated using values reported for other metal adatom-metal adatom activation interactions, such as that of tungsten-tungsten. The above referenced values have been reported, for example, in Neugbauer, C. A. , 1964,  Physics of Thin Films,  2, 1,  Structural Disorder Phenomena in Thin Metal Films.    
     Based on the results of the simulations, a cumulative sticking probability was determined by calculating the fraction of the number of adsorbed monomers which remain on a surface (N ads ) out of the total number of monomers which impinged on the surface (N total ) over a simulated period, in accordance with the equation provided below: 
     
       
         
           
             S 
             = 
             
               
                 N 
                 ads 
               
               
                 N 
                 total 
               
             
           
         
       
     
     The simulations were conducted to simulate depositions using a vapor flux rate corresponding to about 2 Å/s over a deposition period greater than about 8 minutes, which corresponded to a time period for depositing a film having a reference thickness greater than about 96 nm. 
     For typical surfaces, the desorption activation energy (E des ) is generally greater than or equal to the diffusion activation energy (E s ). Based on the simulations, it has now been found, at least in some cases, that surfaces exhibiting a relatively small difference between the desorption activation energy (E des ) and the diffusion activation energy (E s ) may be particularly useful in acting as surfaces of nucleation inhibiting coatings. In some embodiments, the desorption activation energy of a surface is greater than or equal to the diffusion activation energy of the surface and is less than or equal to about 1.1 times, less than or equal to about 1.3 times, less than or equal to about 1.5 times, less than or equal to about 1.6 times, less than or equal to about 1.75 times, less than or equal to about 1.8 times, less than or equal to about 1.9 times, less than or equal to about 2 times, or less than or equal to about 2.5 times the diffusion activation energy of the surface. In some embodiments, the difference (e.g., in terms of absolute value) between the desorption activation energy and the diffusion activation energy is less than about or equal to about 0.5 eV, less than or equal to about 0.4 eV, less than or equal to about 0.35 eV, less than or equal to about 0.3 eV, or less than or equal to about 0.2 eV. In some embodiments, the difference between the desorption activation energy and the diffusion activation energy is between about 0.05 eV and about 0.4 eV, between about 0.1 eV and about 0.3 eV, or between about 0.1 eV and about 0.2 eV. Suitable materials satisfying the foregoing relationships can be identified and selected for depositing a nucleation inhibiting coating. 
     It has also now been found, at least in some cases, that surfaces exhibiting a relatively small difference between the desorption activation energy (E des ) and the dissociation activation energy (E i ) may be particularly useful in acting as surfaces of nucleation inhibiting coatings. In some embodiments, the desorption activation energy (E des ) of a surface is less than or equal to a multiplier times the dissociation activation energy (E i ) of the surface. In some embodiments, the desorption activation energy is less than or equal to about 1.5 times, less than or equal to about 2 times, less than or equal to about 2.5 times, less than or equal to about 2.8 times, less than or equal to about 3 times, less than or equal to about 3.2 times, less than or equal to about 3.5 times, less than or equal to about 4 times, or less than or equal to about 5 times the dissociation activation energy of the surface. Suitable materials satisfying the foregoing relationships can be identified and selected for depositing a nucleation inhibiting coating. 
     It has also now been found, at least in some cases, that surfaces exhibiting a relatively small difference between the diffusion activation energy (E s ) and the dissociation activation energy (E i ) may be particularly useful in acting as surfaces of nucleation inhibiting coatings. In some embodiments, the diffusion activation energy (E s ) of a surface is less than or equal to a multiplier times the dissociation activation energy (E i ) of the surface. In some embodiments, the diffusion activation energy is less than or equal to about 2 times, less than or equal to about 2.5 times, less than or equal to about 2.8 times, less than or equal to about 3 times, less than or equal to about 3.2 times, less than or equal to about 3.5 times, less than or equal to about 4 times, or less than or equal to about 5 times the dissociation activation energy of the surface. Suitable materials satisfying the foregoing relationships can be identified and selected for depositing a nucleation inhibiting coating. 
     In some embodiments, the relationship between the desorption activation energy (E des ), the diffusion activation energy (E s ), and the dissociation activation energy (E i ) of a surface of a nucleation inhibiting coating may be represented as follows: 
     
       
      
       E 
       des 
       ≤α*E 
       s 
       ≤β*E 
       i  
      
     
     wherein α may be any number selected from a range of between about 1.1 and about 2.5, and β may be any number selected from a range of between about 2 and about 5. In some further embodiments, a may be any number selected from a range of between about 1.5 and about 2, and β may be any number selected from a range of between about 2.5 and about 3.5. In another further embodiment, a is selected to be about 1.75 and β is selected to be about 3. Suitable materials satisfying the foregoing relationships can be identified and selected for depositing a nucleation inhibiting coating. 
     It has now been found that surfaces having the following relationship may, at least in certain cases, exhibit a cumulative sticking probability of less than about 0.1 for magnesium vapor: 
         E   des ≤1.75* E   s ≤3* E   i  
 
     Accordingly, surfaces having the above activation energy relationship may be particularly advantageous for use as surfaces of nucleation inhibiting coatings in some embodiments. Suitable materials satisfying the foregoing relationship can be identified and selected for depositing a nucleation inhibiting coating. 
     It has also now been found that surfaces which, in addition to the above activation energy relationships, exhibit a relatively small difference of less than or equal to about 0.3 eV between the diffusion activation energy and the dissociation activation energy may be particularly useful in certain applications, in which a cumulative sticking probability less than about 0.1 is desired. The energy difference (ΔE s-i ) between the diffusion activation energy (E s ) and the dissociation activation energy (E i ) may be calculated according to the following equation: 
       Δ E   s-i   =E   s   −E   i  
 
     For example, it has now been found that, at least in some cases, surfaces wherein the energy difference between the diffusion activation energy and the dissociation activation energy is less than or equal to about 0.25 eV exhibits a cumulative sticking probability of less than or equal to about 0.07 for magnesium vapor. In other examples, ΔE s-i  less than or equal to about 0.2 eV results in a cumulative sticking probability of less than or equal to about 0.05, ΔE s-i  less than or equal to about 0.1 eV results in a cumulative sticking probability of less than or equal to about 0.04, and ΔE s-i  less than or equal to about 0.05 eV results in a cumulative sticking probability of less than or equal to about 0.025. 
     Accordingly in some embodiments, surfaces are characterized by: a is any number selected from a range of between about 1.1 and about 2.5, or a range of between about 1.5 and about 2, such as for example about 1.75, and β is any number selected from a range of between about 2 and about 5, or a range of between about 2.5 and about 3.5, such as for example about 3, in the following inequality relationship: 
     
       
      
       E 
       des 
       ≤α*E 
       s 
       −E 
       i  
      
     
     and wherein ΔE s-i  calculated according to the following equation is less than or equal to about 0.3 eV, less than or equal to about 0.25 eV, less than or equal to about 0.2 eV, less than or equal to about 0.15 eV, less than or equal to about 0.1 eV, or less than or equal to about 0.05 eV in the following equation: 
       Δ E   s-i   =E   s   −E   i  
 
     The results of the calculations were also analyzed to determine the simulated initial sticking probability, which, in the present example, was specified to be the sticking probability of magnesium on a surface upon depositing onto such surface that yields a magnesium coating having an average thickness of about 1 nm. Based on the analysis of the results, it has now been found that, at least in some cases, surfaces wherein the desorption activation energy (E des ) is less than about 2 times the diffusion activation energy (E s ), and the diffusion activation energy (E s ) is less than about 3 times the dissociation activation energy (E i ) generally exhibits a relatively low initial sticking probability of less than about 0.1. 
     Without wishing to be bound by any particular theory, it is postulated that the activation energies of various events and the respective relationships between these activation energies as described above would generally apply to surfaces where the activation energy of adatom reaction to the surface (E b ) is greater than the desorption activation energy (E des ). For surfaces where the activation energy of adatom reaction to the surface (E b ) is less than the desorption activation energy (E des ), it is postulated the initial sticking probability of adatoms on such surfaces would generally be greater than about 0.1. 
     It would be appreciated that various activation energies described above are treated as non-negative values measured in any unit of energy, such as in electron volt (eV). In such cases, the various inequalities and equations relating to activation energies discussed above may be generally applicable across various units of energy. 
     While simulated values of various activation energies have been discussed above, it will be appreciated that these activation energies may also be experimentally measured and/or derived using various techniques. Examples of techniques and instruments which may be used for such purpose include, but are not limited to, thermal desorption spectroscopy, field ion microscopy (FIM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and neutron activation-tracer scanning (NATS). 
     Generally, various activation energies described herein may be derived by conducting quantum chemistry simulations if the general composition and structure of a surface and adatoms are specified (e.g., through experimental measurements and analysis). For simulations, quantum chemistry simulations using methods such as, for example, single energy points, transition states, energy surface scan, and local/global energy minima may be used. Various theories such as, for example, Density Functional Theory (DFT), Hartree-Fock (HF), Self Consistent Field (SCF), and Full Configuration Interaction (FCI) may be used in conjunction with such simulation methods. As would be appreciated, various events such as diffusion, desorption and nucleation may be simulated by examining the relative energies of the initial state, the transition state and the final state. For example, the relative energy difference between the transition state and the initial state may generally provide a relatively accurate estimate of the activation energy associated with various events. 
     As used herein, the terms “substantially,” “substantial,” “approximately,” and “about” are used to denote and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely, as well as instances in which the event or circumstance occurs to a close approximation. For example, when used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, a first numerical value can be deemed to be substantially or about the same as a second numerical value if the first numerical value is within a range of variation of less than or equal to ±10% of the second numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. 
     In the description of some embodiments, a component provided “on” or “over” another component, or “covering” or which “covers” another component, can encompass cases where the former component is directly on (e.g., in physical contact with) the latter component, as well as cases where one or more intervening components are located between the former component and the latter component. 
     Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It can be understood that such range formats are used for convenience and brevity, and should be understood flexibly to include not only numerical values explicitly specified as limits of a range, but also all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. 
     Although the present disclosure has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art. Any examples provided herein are included solely for the purpose of illustrating certain aspects of the disclosure and are not intended to limit the disclosure in any way. Any drawings provided herein are solely for the purpose of illustrating certain aspects of the disclosure and may not be drawn to scale and do not limit the disclosure in any way. The scope of the claims appended hereto should not be limited by the specific embodiments set forth in the above description, but should be given their full scope consistent with the present disclosure as a whole. The disclosures of all documents recited herein are incorporated herein by reference in their entirety.