PATENT DOCUMENT

Publication Number: US-9939703-B1
Application Number: US-201615270698-A
Country: US
Kind Code: B1

Title: Electrochromic devices having reduced switching times and their methods of manufacture

Abstract:
Electrochromic devices having reduced switching times and their methods of manufacturing are presented. In one instance, the electrochromic device includes a transparent substrate having a surface. A first transparent conductive layer is disposed on a portion of the surface. The electrochromic device also includes an optically active layer disposed on the first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field. A second transparent conductive layer is disposed on the optically active layer. The electrochromic device additionally includes a patterned conductive layer disposed on the second transparent conductive layer and defining an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. Other electrochromic devices and methods are presented.

Claims:
What is claimed is: 
     
       1. An electrochromic device comprising:
 a transparent substrate having a surface; 
 a first transparent conductive layer disposed on a portion of the surface; 
 an optically active layer disposed on the first transparent conductive layer, the optically active layer configured to alter an optical property in response to an applied electric field; 
 a second transparent conductive layer disposed on the optically active layer; and 
 a patterned conductive layer disposed on the second transparent conductive layer and defining an array; 
 wherein the array partitions the electrochromic device into a plurality of electrochromic cells. 
 
     
     
       2. The electrochromic device of  claim 1 , further comprising a transparent layer, a portion of which forms an interface with the patterned conductive layer. 
     
     
       3. The electrochromic device of  claim 1 , wherein the patterned conductive layer is a first patterned conductive layer and further comprising a second patterned conductive layer disposed on the first transparent conductive layer; and
 wherein the first patterned conductive layer and the second patterned conductive layer define the array. 
 
     
     
       4. The electrochromic device of  claim 1 , wherein the optical property is selected from an absorption spectrum of electromagnetic radiation and a reflection spectrum of electromagnetic radiation. 
     
     
       5. The electrochromic device of  claim 1 , further comprising:
 a power distribution circuit electrically coupled to the first transparent conductive layer and the patterned conductive layer; 
 the power distribution circuit configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells. 
 
     
     
       6. The electrochromic device of  claim 5 , further comprising an electrical power source coupled to the power distribution circuit. 
     
     
       7. The electrochromic device of  claim 5 , wherein the power distribution circuit comprises an electrical switch, the electrical switch configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells. 
     
     
       8. The electrochromic device of  claim 1 , wherein the optically active layer comprises an electrochromic layer, an ion conductive layer, and an ion storage layer. 
     
     
       9. The electrochromic device of  claim 1 , wherein the patterned conductive layer comprises a metal selected from copper, aluminum, silver, and gold. 
     
     
       10. The electrochromic device of  claim 1 , wherein the patterned conductive layer comprises a polymer material having a resistivity lower than 10 −3  Ω-cm. 
     
     
       11. An electrochromic device comprising:
 a glass substrate having a surface; 
 a first transparent conductive layer disposed on a portion of the surface; 
 an optically active layer disposed on the first transparent conductive layer and having an electrochromic layer, an ion conductive layer, and an ion storage layer therein, the electrochromic layer configured to alter an absorption spectrum of electromagnetic radiation in response to an applied electric field; 
 a second transparent conductive layer disposed on the optically active layer; 
 a patterned conductive layer disposed on the second transparent conductive layer and defining an array; and 
 a glass superstrate having a portion bonded onto the patterned conductive layer; 
 wherein the array partitions the electrochromic device into a plurality of electrochromic cells. 
 
     
     
       12. The electrochromic device of  claim 11 ,
 wherein the patterned conductive layer is a first patterned conductive layer, and further comprising a second patterned conductive layer disposed on the first transparent conductive layer; and 
 wherein the first patterned conductive layer and the second patterned conductive layer define the array. 
 
     
     
       13. The electrochromic device of  claim 11 , wherein the patterned conductive layer comprises a metal selected from copper, aluminum, silver, and gold. 
     
     
       14. The electrochromic device of  claim 11 , wherein the patterned conductive layer comprises a polymer material having a resistivity lower than 10 −3  Ω-cm. 
     
     
       15. A method of manufacturing an electrochromic device, the method comprising:
 forming an optically active layer onto a first transparent conductive layer, the first transparent conductive layer disposed on a portion of a transparent substrate; 
 depositing a second transparent conductive layer onto the optically active layer; and 
 patterning a conductive material into an array on the second transparent conductive layer to partition the electrochromic device into a plurality of electrochromic cells; 
 wherein the optically active layer is configured to alter an optical property in response to an applied electric field. 
 
     
     
       16. The method of  claim 15 , further comprising bonding a transparent superstrate to the patterned conductive material. 
     
     
       17. The method of  claim 15 , wherein the optically active layer comprises an electrochromic layer, an ion conductive layer, and an ion storage layer. 
     
     
       18. The method of  claim 15 , wherein patterning the conductive material into the array comprises:
 depositing a precursor fluid onto the second transparent conductive layer using a process selected from rotogravure printing, ink-jet printing, screen-printing, and stamping. 
 
     
     
       19. The method of  claim 15 , wherein patterning the conductive material into the array comprises:
 coating a photoresist layer onto the second transparent conductive layer; 
 exposing a portion of the photoresist layer to an electromagnetic radiation, the portion corresponding to a configuration of the array; 
 removing, after exposure to the electromagnetic radiation, the portion, thereby defining an opening through the photoresist layer; 
 depositing the conductive material onto the second transparent conductive layer through the opening; and 
 removing an unexposed portion of the photoresist layer from the second transparent conductive layer. 
 
     
     
       20. The method of  claim 19 , wherein exposing the portion of the layer of photoresist comprises receiving a beam of electromagnetic radiation from a laser writing system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 62/234,319, filed Sep. 29, 2015, and entitled “Electrochromic Devices Having Reduced Switching Times and Their Methods of Manufacture,” which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The described embodiments relate generally to electrochromic devices, and more particularly, to electrochromic devices having patterned conductors for reducing switching times. 
     BACKGROUND 
     Electrochromic devices include an optically active layer disposed between two conductive layers. The two conductive layers are transparent, and during operation, apply voltages to the optically active layer. Such voltages correspond to electric fields passing through the optically active layer. The optically active layer is formed of materials whose light transmittance changes in response to applied electric fields. Thus, each applied voltage induces a transmissive state in the optically active layer. By selectively manipulating the applied voltage, electrochromic devices can switch into a desired transmissive state and regulate light passing therethrough. In general, increased voltages correspond to transmissive states that have a lower transmittance of light. 
     Electrochromic devices have been integrated into glass panes to produce so-called “smart windows” that selectively regulate light transmission. Within a “smart window,” an electrochromic device spans a functional area of a glass pane, which can be the entirety of the pane. In this configuration, electrical coupling to conductive layers occurs from a perimeter of the glass pane, thereby requiring an electrical charge to move inward when voltages are applied. For this reason, conventional “smart windows” are observed to first darken (or lighten) from their edges to achieve a uniform transmissive state. This darkening (or lightening) then travels inward. Such an effect creates delays when switching between transmissive states. 
     The delayed switching times can be influenced by sheet resistances associated with the two conductive layers. In operation, electrical charges traveling inward from the perimeter must overcome a cumulative resistance that increases with distance. Thus, during operation, a voltage distribution across the two conductive layers is initially non-uniform, i.e., voltages experienced by the optically active layer can decrease when traveling inward and away from the perimeter. Thus, there is a need for electrochromic devices that reduce sheet resistance effects associated with the conductive layers. 
     SUMMARY 
     The embodiments described herein relate to electrochromic devices having reduced switching times, including methods for manufacturing such electrochromic devices. In one illustrative embodiment, the electrochromic device includes a transparent substrate having a surface. A first transparent conductive layer is disposed on a portion of the surface. The electrochromic device also includes an optically active layer disposed on the first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). A second transparent conductive layer is disposed on the optically active layer. The electrochromic device additionally includes a patterned conductive layer disposed on the second transparent conductive layer and defining an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. 
     In another illustrative embodiment, the electrochromic device includes a glass substrate having a surface. A first transparent conductive layer is disposed on a portion of the surface. The electrochromic device also includes an optically active layer disposed on the first transparent conductive layer and having an electrochromic layer, an ion conductive layer, and an ion storage layer therein. The optically active layer is configured to alter an absorption spectrum of electromagnetic radiation in response to an applied electric field (i.e., an applied voltage). A second transparent conductive layer is disposed on the optically active layer. The electrochromic device additionally includes a patterned conductive layer disposed on the second transparent conductive layer, defining an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. The electrochromic device also includes a glass superstrate having a portion bonded onto the patterned conductive layer. 
     In an additional illustrative embodiment, a method of manufacturing an electrochromic device includes forming an optically active layer onto a first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field. The first transparent conductive layer is disposed on a portion of a transparent substrate. The method also includes depositing a second transparent conductive layer onto the optically active layer and patterning a conductive material into an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. 
     It will be appreciated that the patterned conductive layer has a greater conductivity than the second transparent conductive layer. This greater conductivity enables an alternate, lower-resistance electrical conduit that mitigates sheet resistance effects. Electrical charge can therefore reach areas throughout the second transparent conductive layer, but with minimal losses in voltage potential. Moreover, the plurality of electrochromic cells subdivides the electrochromic device into smaller regions, allowing the optically active layer to experience a more uniform voltage distribution. Deviations from the applied voltage are also significantly reduced. Thus, by virtue of the patterned conductive layer, the transmissive state emerges more evenly throughout the optically active layer and switching times between transmissive states are reduced. In some embodiments, features of the array are such that the patterned conductive layer is not visible to the naked eye. Other electrochromic devices and methods are presented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements. Although the following figures and description illustrate specific embodiments and examples, the skilled artisan will appreciate that various changes and modifications may be made without departing from the spirit and scope of the disclosure. 
         FIG. 1A  is a perspective view, with a portion shown in cross-section, of a window having a plurality of selectively transparent panels, according to an illustrative embodiment. 
         FIG. 1B  is a detail view, shown in cross-section, of an electrochromic device incorporated into each of the plurality of selectively transparent panels of  FIG. 1A , according to an illustrative embodiment. 
         FIG. 2  is a perspective view of a cross-sectioned portion of an electrochromic device, according to an illustrative embodiment. 
         FIG. 3  is a portion of an electrochromic device, shown in cross-section, in which an optically active layer includes an electrochromic layer, an ion conductive layer, and an ion storage layer, according to an illustrative embodiment. 
         FIG. 4  is side view of a cross-sectioned portion of another electrochromic device with two patterned conductive layers and an insert of the top view thereof, according to an illustrative embodiment. 
         FIG. 5  is a side view of a cross-sectioned portion of an electrochromic device with portions of the optically active layer and second transparent conductive layer removed and an insert of the top view thereof, according to an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Referring to  FIG. 1A , a perspective view is presented, with a portion shown in cross-section, of a window  100  having a plurality of selectively transparent panels  102 , according to an illustrative embodiment.  FIG. 1A  presents the window  100  in the context of a building structure. However, other contexts are possible (e.g., vehicular windows). Moreover, the window  100  is depicted as being exposed to solar radiation  104  from the sun  106 . This depiction, however, is not intended as limiting. The window  100 , for example, could be disposed within an interior room of a building. Other environments are possible. The plurality of selectively transparent panels  102  have a planar configuration and are individually supported within a frame  108  of the window  100 . It will be appreciated, however, that the plurality of selectively transparent panels  102  can have non-planar configurations (e.g., concave, convex, etc.). For example, and without limitation, the plurality of selectively transparent panels  102  could function as windows for a vehicle and have shapes that conform thereto (i.e., curved to match a profile of the vehicle 
     An electrochromic device  110  can be incorporated into each of the plurality of selectively transparent panels  102 . The electrochromic device  110  interacts with an incoming light  112  that enters the window  100 . For purposes of clarity,  FIG. 1A  depicts only one selectively transparent panel  102  interacting with the incoming light  112 . However, it will be understood that all panels  102  of the plurality of selectively transparent panels  102  are capable of interacting with the incoming light  112 . Interaction of the electrochromic device  110  with the incoming light  112  produces a transmitted light  114 . The transmitted light  114  can be reduced in intensity relative to the incoming light  112 . However, the electrochromic device  110  may also alter a spectral distribution, a polarization, or both, of the incoming light  112  to produce the transmitted light  114 . In some embodiments, interaction of the electrochromic device  110  with the incoming light  112  may also produce a reflected light  116 . Non-limiting examples of the incoming light  112  include the sun, incandescent lamps, fluorescent lamps, LED lamps, and combustion lamps. Other sources for the incoming light  112  are possible. 
       FIG. 1B  presents a detail view, shown in cross-section, of the electrochromic device  110  incorporated into each of the plurality of selectively transparent panels  102  of  FIG. 1A . The electrochromic device  110  includes an optically active layer  118  disposed between a first transparent conductive layer  120  and a second transparent conductive layer  122 . During operation, the first transparent conductive layer  120  and the second transparent conductive layer  122  apply a voltage across the optically active layer  118  thereby generating an applied electric field. The electrochromic device  110  also includes a patterned conductive layer  124  disposed on the second transparent conductive layer  122 . The patterned conductive layer  124  defines an array on the second transparent conductive layer  122  and partitions the electrochromic device  110  into a plurality of electrochromic cells. In some embodiments, features of the array are such that the patterned conductive layer is not visible to the naked eye. 
     In  FIG. 1B , the array is depicted as a rectilinear array. However, this depiction is for purposes of illustration only. The array may include any combination of vertexes and segments therebetween that define a two-dimensional pattern across a surface  126  of the second transparent conductive layer  122 . As will be described further in relation to  FIG. 2 , the patterned conductive layer  124  reduces sheet resistance effects associated with the second transparent conductive layer  122 . The electrochromic device  110  can be disposed between two transparent substrates to create a sandwich structure. In some embodiments, the transparent substrates can be panes of glass  128 , in other embodiments, the transparent substrates can be polymers, resins, or other types of transparent materials. 
     In operation, a voltage is applied across the optically active layer  118  using the first transparent conductive layer  120 , the second transparent conductive layer  122 , and the patterned conductive layer  124 . In response to the applied voltage, the optically active layer  118  enters a transmissive state that regulates light passing through the electrochromic device  110 . Such regulation includes altering an intensity of light, a spectral distribution of light, a polarization of light, or any combination thereof. 
     The transmissive state may be characterized by a percentage that ranges between a minimum transmittance (0% transmittance) and a maximum transmittance (100% transmittance). 
     By varying the voltage applied to the optically active layer  118 , different transmissive states can be accessed. Such variation enables the electrochromic device  110  to selectively control the amount of the transmitted light  114  from the incoming light  112 , and/or the amount of the reflected light  116 . Thus, the electrochromic device  110  allows the selectively transparent panels  102  to control their transparency to light. In some embodiments, the voltage can be applied continuously to maintain a selected transmissible state. In other embodiments, the voltage need not be applied continuously to the optically active layer  118  to maintain the transmissive state. In these embodiments, the voltage need only be applied during a limited duration until the transmissive state is achieved. It will be appreciated that switching between different transmissive states can involve a time delay. This time delay would otherwise scale appreciably with a size of the plurality of selectively transparent panels  102  if the patterned conductive layer  124  were not present. 
     Referring to  FIG. 2 , a perspective view is presented of a cross-sectioned portion of an electrochromic device  200 , according to an illustrative embodiment. The electrochromic device  200  includes a transparent substrate  202  having a surface  204 . The transparent substrate  202  can be formed of an amorphous material such as a soda-lime glass or a borosilicate glass. The electrochromic device  200  also includes a first transparent conductive layer  206  disposed on the surface  204  of the transparent substrate  202 . The first transparent conductive layer  206  is commonly a transparent conducting oxide (TCO), although other transparent conducting materials are possible. Non-limiting examples of transparent conducting oxides include F:SnO 2 , Sn:In 2 O 3 , and Al:ZnO. In other embodiments, the transparent conductive layer can be a zinc nitride material or a titanium nitride material. 
     An optically active layer  208  is disposed on the first transparent conductive layer  206  and configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). During operation, the optical properties are altered to interact with an incoming light to produce a transmitted light. Such interaction can involve attenuating a spectral portion of the incoming light. The spectral portion may include an individual wavelength or a range of wavelengths. Attenuation of the incoming light may involve absorption, reflection, polarization, or combinations thereof. Other optical processes are possible. The applied voltage controls strength of attenuation and also establishes a transmissive state in the optically active layer  208 . 
     In some embodiments, the optical properties can include an absorption spectrum of electromagnetic radiation. In these embodiments, wavelengths of the spectral portion can be absorbed in proportions defined by the absorption spectrum of electromagnetic radiation. In some embodiments, the optical properties can include a reflection spectrum of electromagnetic radiation. In these embodiments, wavelengths of the spectral portion can be reflected in proportions defined by the reflection spectrum of electromagnetic radiation. 
     In some embodiments, the optically active layer  208  can include an electrochromic layer, an ion conductive layer, and an ion storage layer. The electrochromic layer can incorporate a transition metal oxide such as NiO, V 2 O 5 , TiO 2 , Nb 2 O 5 , MoO 3 , Ta 2 O 5 , and WO 3 . Other materials, however, are possible (e.g., electrochromic polymers). The ion-conductive layer, which is disposed between the electrochromic layer and the ion storage layer, can include an electrolyte that allows ions to diffuse therethrough. Such ions may include H + , Li + , Na + , K + , or combinations thereof. The ion-conductive layer may be a polymeric electrolyte or a gel electrolyte. Other types of electrolytes are possible. The ion storage layer, or counter electrode, serves to receive ions from and release ions into the ion conductive layer. The ion storage layer is commonly formed of a transition metal oxide (e.g., NiO, V 2 O 5 , TiO 2 , etc.). 
     The electrochromic device  200  includes a second transparent conductive layer  210  disposed on the optically active layer  208 . The second transparent conductive layer  210  can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. In some embodiments, the second transparent conductive layer  210  can comprise a transparent conducting oxide that is the same as the first transparent conducting layer  206 . In other embodiments, the second transparent conductive layer  210  and the first transparent conductive layer  206  can be different transparent conducting oxide materials. 
     The electrochromic device  200  also includes a patterned conductive layer  212  disposed on the second transparent conductive layer  210  and defining an array  214  on the second transparent conductive layer  210 . The array  214  partitions the electrochromic device  200  into a plurality of electrochromic cells  216 . In  FIG. 2 , the array  214  is depicted as a rectilinear array. However, this depiction is not intended as limiting. The array  214  may include any pattern that defines two-dimensional cells across a surface of the second transparent conductive layer  210 . For example, the array can be a series of cells that can be rectilinear, triangular-shaped, diamond-shaped, pentagonal-shaped, hexagonal-shaped, octagonal-shaped, combinations thereof, or any other geometric shape. 
     In some embodiments, features of the array  214  are such that the patterned conductive layer  212  is not visible to the naked eye. For example, and without limitation, the array  214  may include conductive nanowires. In another non-limiting example, the array  214  may be formed using a conductive ink that, when hardened or dried, provides semi-transparency. The conductive ink can include a fluid having a transparent, conductive polymer dissolved therein. The conductive ink can also include metallic particles, which may be nanoparticles. Other features, however, are possible for the array  214 . 
     To overcome sheet resistances, the patterned conductive layer  212  can have a greater conductivity than the second transparent conductive layer  210 . This greater conductivity allows an electrical charge to use the patterned conductive layer  212  as an alternate, lower-resistance electrical conduit during operation. The electrical charge distributes through the patterned conductive layer  212  and reaches areas throughout the second transparent conductive layer  210  having lost minimal voltage potential. Moreover, the plurality of electrochromic cells  216  subdivides the electrochromic device  200  into smaller regions, allowing the optically active layer  208  to experience a more uniform voltage distribution (or distribution in voltage potential). Deviations from the applied voltage can be reduced. Thus, by virtue of the patterned conductive layer  212 , the transmissive state can emerge more evenly throughout the optically active layer  208 , and switching times between transmissive states can be reduced. 
     In some embodiments, the patterned conductive layer  212  can include a portion that can generate heat by resistive heating. In these embodiments, heat flows through the second transparent conductive layer  210  and into the optically active layer  208 . 
     In some embodiments, the patterned conductive layer  212  includes a metal selected from the group consisting of copper, aluminum, silver, and gold. In further embodiments, the metal includes nanoparticles having dimensions less than 750 nm. In some embodiments, the patterned conductive layer  212  includes a polymer material having a resistivity lower than 10 −3  Ω-cm. In these embodiments, the polymer material may be transparent. Non-limiting examples of the polymer material include PEDOT, i.e., poly(3,4-ethylenedioxythiophene) and PEDOT:PSS, i.e., poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). In further embodiments, the polymer material incorporates particles of metal therein (e.g., Cu, Al, Ag, Ag, Pt, etc.). In some embodiments, the patterned conductive layer  212  includes carbon nanomaterials. Non-limiting examples of carbon nanomaterials include graphene, fullerenes, and carbon nanotubes. 
     In some embodiments, the electrochromic device  200  can further include a transparent layer, a portion of which forms an interface with the patterned conductive layer  212 . The transparent layer can be bonded to the patterned conductive layer  212 , the second transparent conductive layer  210 , or both. The transparent layer may be a superstrate body, such as a glass pane. The transparent layer may also be a coating, such as an epoxy coating, a thermoplastic coating, or other organic-based coatings. 
     In some embodiments, the electrochromic device  200  can further include a power distribution circuit electrically coupled to the first transparent conductive layer  206  and the patterned conductive layer  212 . In such embodiments, the power distribution circuit is configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells  216 . The power distribution circuit may have an electrical power source coupled thereto. In some embodiments, the power distribution circuit includes an electrical switch. In these embodiments, the electrical switch is configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells  216 . This regulation may include selectively applying voltages to individual electrochromic cells  216  in order to produce patterns of transmissive states across the electrochromic device  200 . Non-limiting examples of patterns include gradients in shading, step-contrasts between shaded and non-shaded regions, and shading that defines informational characters (e.g., text). Other types of patterns of transmissive states are possible. 
     In some embodiments, the electrochromic device  200  further includes a glass superstrate having a portion bonded onto the patterned conductive layer  212 . In such embodiments, the transparent substrate  202  is a glass substrate. Moreover, the optically active layer  208  includes the electrochromic layer, the ion conductive layer, and the ion storage layer. The electrochromic layer is configured to alter the absorption spectrum of electromagnetic radiation in response to the applied electric field. In these embodiments, the patterned conductive layer can include a metal selected from the group consisting of copper, aluminum, silver, and gold. The patterned conductive layer can also include the polymer material having a low resistivity (e.g. lower than 10 −3  Ω-cm). The polymer material may be utilized independently or in combination with the metal. 
     In operation, the electrochromic device  200  receives the incoming light and, depending on the optical properties altered by the optically active layer  208 , produces the transmitted light.  FIG. 3  presents a portion of an electrochromic device  300 , shown in cross-section, in which the optically active layer  308  includes an electrochromic layer  318 , an ion conductive layer  320 , and an ion storage layer  322 , according to an illustrative embodiment. An incoming light  324  is received by patterned conductive layer  312  and traverses the electrochromic device  300  to exit as a transmitted light  326 . The transmitted light  326  is altered relative to the incoming light  324  due to optical interactions within the optically active layer  308 . 
     An electrical power source  328  is coupled to the patterned conductive layer  312  and the first transparent conductive layer  306  via a power distribution circuit  330 .  FIG. 3  depicts the electrical power source  328  as a battery. However, this depiction is for purposes of illustration only. Other types of electrical power sources are possible. The power distribution circuit  330  enables the electrical power source  328  to apply a voltage between the patterned conductive layer  312  and the first transparent conductive layer  306 . The voltage creates an electric field  332  within the optically active layer  308 . An electrical switch  334  allows the voltage experienced by the electrochromic device  300  to be adjusted in magnitude. The electric field  332  scales in proportion to the applied (or adjusted) voltage. In  FIG. 3 , the electric switch is depicted as a potentiometer. However, this depiction is not intended as limiting. Other types of electric switches are possible (e.g., a transistor). The applied voltage induces a flow of current  336  within the power distribution circuit  330  that includes the electrochromic device  300 . The flow of current  336  is illustrated in  FIG. 3  by dashed arrows that represent a motion of negative charge (i.e., a motion of e − ). It will be appreciated that the flow of current  336  moves in a direction opposite of the electric field  332  when traversing the electrochromic device  300 . 
     The flow of current  336  delivers a negative charge to the electrochromic layer  318  via the first transparent conductive layer  306 . In response, positive ions (i.e., M + ) diffuse out of the ion storage layer  322 , through the ion conductive layer  320 , and into the electrochromic layer  318 . Such diffusion occurs in a same direction as the applied current  336 . The diffusion of positive ions  338  is depicted in  FIG. 3  by solid arrows. Materials in the electrochromic layer  318  change composition upon receiving the flow of positive ions  338 . This compositional change can alter the optical properties of the electrochromic layer  318 . A non-limiting example of such compositional changes is provided below:
 
 y Li +   +ye   − +W VI O 3 →Li y W V   y W IV   1-y O 3  
 
In this non-limiting example, lithium ions intercalate into tungsten oxide to produce a lithium tungstate compound. As intercalation proceeds, the lithium tungstate compound alters its absorption spectrum to favor blue wavelengths. Thus, an electrochromic layer incorporating tungsten oxide (i.e., WO 3 ) would become increasingly blue in tint as lithium ions were increasingly absorbed. In other embodiments, other ion-metal oxide compounds can be used to alter the absorption to favor other colors/wavelengths.
 
     The flow of positive ions  338  continues until the ion storage layer  322  becomes sufficiently depleted that the strength of the electric field  332  is unable to extract further ions. At this point, the optically active layer  308  exhibits a stable transmissive state. In some embodiments, the voltage can be removed yet the transmissive state persists. The optically active layer  308  can be switched into a new transmissive state by altering the voltage. For example, and without limitation, an electrochromic layer incorporating tungsten oxide (i.e., WO 3 ) can increase in blue tint by applying a voltage higher than the previous voltage. Alternatively, the voltage could be reversed to decrease the blue tint. Other manipulations of the voltage are possible. In general, the voltage applied by the power distribution circuit  330  can be manipulated by the electrical switch  334  to transition the electrochromic device  300  between transmissive states. Such manipulation alters the optical properties of the optically active layer  308 . 
     It will be appreciated that the patterned conductive layer  312  enables a more uniform voltage distribution than if the power distribution circuit  330  were coupled directly to the second transparent conductive layer  210 . By virtue of its higher conductivity, the patterned conductive layer  312  serves as an alternate, lower-resistance electrical conduit for the flow of current  336 . Moreover, the plurality of electrochromic devices  316  subdivide the electrochromic device  300  into smaller regions. The flow of current  336  therefore is able to distribute across the second transparent conductive layer  210  with minimal losses in voltage potential. As a result, the transmissive state emerges more evenly throughout the optically active layer  308  and switching times between transmissive states are reduced. In embodiments where the patterned conductive layer  312  generates heat, i.e., via a portion thereof, such heat is absorbed by the optically active layer  308 . This heat increases ion diffusion within the optically active layer  308 , further reducing switching times. 
     In some embodiments, the electrochromic device can include two patterned conductive layers. An optically active layer is disposed between the two patterned conductive layers.  FIG. 4  depicts presents a cross-sectioned portion of an electrochromic device  400 , according to an illustrative embodiment. The electrochromic device  400  includes a transparent substrate  402 . As previously described, the transparent substrate  402  can be formed of an amorphous material such as, but not limited to, a soda-lime glass or a borosilicate glass. The electrochromic device  400  also includes a first transparent conductive layer  406  disposed the transparent substrate  402 . The first transparent conductive layer  406  can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. Non-limiting examples of transparent conducting oxides include F:SnO 2 , Sn:In 2 O 3 , and Al:ZnO. In other embodiments, the transparent conductive layer can be a zinc nitride material or a titanium nitride material. 
     An optically active layer  408  is disposed on the first transparent conductive layer  406 , and is configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). During operation, the optical properties are altered to interact with incoming light to produce transmitted light. Such interaction can involve attenuating a spectral portion of the incoming light. The spectral portion can include an individual wavelength or a range of wavelengths. Attenuation of the incoming light can involve absorption, reflection, polarization, or combinations thereof. Other optical processes are possible. The applied voltage controls strength of attenuation and can also establish a transmissive state in the optically active layer  208 . 
     In some embodiments, the optically active layer  408  can include an electrochromic layer, an ion conductive layer, and an ion storage layer. The electrochromic layer can incorporate a transition metal oxide such as NiO, V 2 O 5 , TiO 2 , Nb 2 O 5 , MoO 3 , Ta 2 O 5 , and WO 3 . Other materials are possible (e.g., electrochromic polymers). The ion-conductive layer, which is disposed between the electrochromic layer and the ion storage layer, can include an electrolyte that allows ions to diffuse therethrough. Such ions may include H + , Li + , Na + , K + , or combinations thereof. The ion-conductive layer may be a polymeric electrolyte or a gel electrolyte. Other types of electrolytes are possible. The ion storage layer, or counter electrode, serves to receive ions from and release ions into the ion conductive layer. The ion storage layer is commonly formed of a transition metal oxide (e.g., NiO, V 2 O 5 , TiO 2 , etc.). 
     The electrochromic device  400  includes a second transparent conductive layer  410  disposed on the optically active layer  408 . The second transparent conductive layer  410  can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. In some embodiments, the second transparent conductive layer  410  can comprise a transparent conducting oxide that is the same as the first transparent conducting layer  406 . In other embodiments, the second transparent conductive layer  410  and the first transparent conductive layer  406  can be different transparent conducting oxide materials. 
     The electrochromic device  400  also includes a first patterned conductive layer  412  disposed on the first transparent conductive layer  406 . The electrochromic device  400  also includes a second patterned conductive layer  422  disposed on the second transparent conductive layer  410 . Collectively, the first patterned conductive layer  412  and the second patterned conductive layer  422  define an array  414  that partitions the electrochromic device  400  into a plurality of electrochromic cells  416 . The array  414  partitions the electrochromic device  400  into a plurality of electrochromic cells  416 . 
     In  FIG. 4 , the array  414  is depicted as a rectilinear array. However, this depiction is not intended as limiting. The array  414  may include any pattern that defines three-dimensional cells across the optically active layer  408 . For example, the array can be a series of cells that can be rectilinear, triangular-shaped, diamond-shaped, pentagonal-shaped, hexagonal-shaped, octagonal-shaped, combinations thereof, or any other geometric shape. 
     In some embodiments, features of the array  414  are such that the patterned conductive layers  412  and  422  are not visible to the naked eye. For example, and without limitation, the array  414  may include conductive nanowires. In another non-limiting example, the array  414  may be formed using a conductive ink that, when hardened or dried, provides semi-transparency. The conductive ink can include a fluid having a transparent, conductive polymer dissolved therein. The conductive ink can also include metallic particles, which may be nanoparticles. Other features, however, are possible for the array  414 . 
     To overcome sheet resistances, the patterned conductive layers  412  and  422  can have greater conductivity than the first and second transparent conductive layers  406  and  410 . This greater conductivity allows an electrical charge to use the patterned conductive layers  412  and  422  as an alternate, lower-resistance electrical conduit during operation. The electrical charge distributes through the patterned conductive layers  412  and  422 , and reaches areas throughout the transparent conductive layers  406  and  410  having lost minimal voltage potential. Moreover, the plurality of electrochromic cells  416  subdivides the electrochromic device  400  into smaller regions, allowing the optically active layer  408  to experience a more uniform voltage distribution (or distribution in voltage potential). Thus, by virtue of the patterned conductive layers  412  and  422 , the transmissive state can emerge more evenly throughout the optically active layer  408 , and switching times between transmissive states can be reduced. 
     In some embodiments, the electrochromic device  400  can further include a transparent layer (not shown), a portion of which forms an interface with the second patterned conductive layer  422 . The transparent layer can be bonded to the second patterned conductive layer  422 , the second transparent conductive layer  410 , or both. The transparent layer may be a superstrate body, such as a glass or plexiglass pane. The transparent layer may also be a coating, such as an epoxy coating, a thermoplastic coating, or other organic-based coatings. 
     In some embodiments, like the electrochromic device  200 , electrochromic device  400  can further include a power distribution circuit electrically coupled to the transparent conductive layers  406  and  410  and the patterned conductive layers  412  and  422 . In such embodiments, the power distribution circuit is configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells  416 . The power distribution circuit may have an electrical power source coupled thereto. In some embodiments, the power distribution circuit includes an electrical switch. In these embodiments, the electrical switch is configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells  416 . This regulation may include selectively applying voltages to individual electrochromic cells  416  in order to produce patterns of transmissive states across the electrochromic device  400 . Non-limiting examples of patterns include gradients in shading, step-contrasts between shaded and non-shaded regions, and shading that defines informational characters (e.g., text). Other types of patterns of transmissive states are possible. 
     In some embodiments the electrochromic device can have portions of a transparent conductive layer and the optically active layer removed to further partition the device into electrochromic cells.  FIG. 5  depicts presents a cross-sectioned portion of an electrochromic device  500 , according to an illustrative embodiment. The electrochromic device  500  includes a transparent substrate  502 . As previously described, the transparent substrate  502  is typically formed of an amorphous material such as a soda-lime glass or a borosilicate glass. The electrochromic device  500  also includes a first transparent conductive layer  506  disposed on the transparent substrate  502 . The first transparent conductive layer  506  is commonly a transparent conducting oxide (TCO), although other transparent conducting materials are possible. Non-limiting examples of transparent conducting oxides include F:SnO 2 , Sn:In 2 O 3 , and Al:ZnO. In other embodiments, the transparent conductive layer can be a zinc nitride material or a titanium nitride material. 
     An optically active layer  508  is disposed on the first transparent conductive layer  506  and configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). In some embodiments, the optically active layer  508  can include an electrochromic layer, an ion conductive layer, and an ion storage layer. The electrochromic layer can incorporate a transition metal oxide such as NiO, V 2 O 5 , TiO 2 , Nb 2 O 5 , MoO 3 , Ta 2 O 5 , and WO 3 . Other materials, however, are possible (e.g., electrochromic polymers). The ion-conductive layer, which is disposed between the electrochromic layer and the ion storage layer, can include an electrolyte that allows ions to diffuse therethrough. Such ions may include H + , Li + , Na + , K + , or combinations thereof. The ion-conductive layer may be a polymeric electrolyte or a gel electrolyte. Other types of electrolytes are possible. The ion storage layer, or counter electrode, serves to receive ions from and release ions into the ion conductive layer. The ion storage layer is commonly formed of a transition metal oxide (e.g., NiO, V 2 O 5 , TiO 2 , etc.). 
     The electrochromic device  500  includes a second transparent conductive layer  510  disposed on the optically active layer  508 . The second transparent conductive layer  510  can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. In some embodiments, the second transparent conductive layer  510  can comprise a transparent conducting oxide that is the same as the first transparent conducting layer  506 . In other embodiments, the second transparent conductive layer  510  and the first transparent conductive layer  506  can be different transparent conducting oxide materials. 
     The electrochromic device  500  also includes a first patterned conductive layer  512  disposed between the first transparent conductive layer  506  and the optically active layer  508 . The electrochromic device  500  also includes a second patterned conductive layer  522  disposed on the second transparent conductive layer  510 . Collectively, the first patterned conductive layer  512  and the second patterned conductive layer  522  define an array  514  along with the optically active layer  508  that partitions the electrochromic device  500  into a plurality of electrochromic cells  516 . 
     Further, the electrochromic cells  516  can be defined by removing select portions of the optically active layer  508  and the second transparent conductive layer  510 . As shown in  FIG. 5 , it is illustrated that selective portions  508   a  of the optically active layer and selective portions  510   a  of the second transparent conductive layer that correspond to the pattern of the first and second patterned conductive layers  512  and  522  are removed. To remove portions  508   a  of the optically active layer and portions  510   a  of the second transparent conductive layer, the optically active layer  508  and the second transparent conductive layer  510  can be selectively ablated. In some embodiments, portions  508   a  of the optically active layer and portions  510   a  of the second transparent conductive layer can be removed by laser ablation by heating portions  508   a  and portions  510   a  to evaporate or sublimate the portions. Other possible methods for ablation are possible 
     In other embodiments, portions  508   a  of the optically active layer and portions  510   a  can be removed by using a lithography process. In such embodiments, the optically active layer may be deposited along with the use of a mask that is patterned. The patterned mask can be overlaid on the first transparent conductive layer  506  such that regions of the first transparent conductive layer are covered with the mask thereby preventing the deposition of the optically active layer on the first transparent conductive layer  506 . These regions correspond to portions  508   a  of the optically active layer. Then, the second transparent layer  510  can be deposited on the optically active layer  508  while the mask is still overlaid on the first transparent conductive layer  506 . The regions of the mask that cover the first transparent conductive layer  506  also correspond to portions  510   a  of the second transparent conductive layer  510 . After deposition of the optically active layer  508  and the second transparent conductive layer  510 , the mask can be removed such that portions of the first transparent conductive layer  506  are exposed. Then, the first patterned conductive layer  512  can be deposited on the exposed portions of the first transparent conductive layer  506  to create array  516 . In other embodiments, the first patterned conductive layer  512  may be deposited before the optically active layer  508  and the second transparent layer  510 . In such embodiments, the mask is overlaid on both the first transparent conductive layer  506  and the first patterned conductive layer  512 . 
     In  FIG. 5 , the array  514  is depicted as a rectilinear array, like electrochromic devices  200  and  400 . However, this depiction is not intended as limiting. The array  514  may include any pattern that defines three-dimensional cells across the optically active layer  508 . For example, the array can be a series of cells that can be rectilinear, triangular-shaped, diamond-shaped, pentagonal-shaped, hexagonal-shaped, octagonal-shaped, combinations thereof, or any other geometric shape. 
     In some embodiments, features of the array  514  are such that the patterned conductive layers  512  and  522  are not visible to the naked eye. For example, and without limitation, the array  514  may include conductive nanowires. In another non-limiting example, the array  514  may be formed using a conductive ink that, when hardened or dried, provides semi-transparency. The conductive ink can include a fluid having a transparent, conductive polymer dissolved therein. The conductive ink can also include metallic particles, which may be nanoparticles. Other features, however, are possible for the array  514 . 
     Like the previously described embodiments, o overcome sheet resistances, the patterned conductive layers  512  and  522  can have greater conductivity than the first and second transparent conductive layer  506  and  510 . This greater conductivity allows an electrical charge to use the patterned conductive layers  512  and  522  as an alternate, lower-resistance electrical conduit during operation. The electrical charge distributes through the patterned conductive layers  512  and  522 , and reaches areas throughout the transparent conductive layers  506  and  510  having lost minimal voltage potential. Moreover, the plurality of electrochromic cells  516  subdivides the electrochromic device  500  into smaller regions, allowing the optically active layer  408  to experience a more uniform voltage distribution (or distribution in voltage potential). Thus, by virtue of the patterned conductive layers  512  and  522 , the transmissive state can emerge more evenly throughout the optically active layer  508 , and switching times between transmissive states can be reduced. 
     In some embodiments, the electrochromic device  500  can further include a transparent layer (not shown), a portion of which forms an interface with the second patterned conductive layer  522 . The transparent layer can be bonded to the second patterned conductive layer  522 , the second transparent conductive layer  510 , or both. The transparent layer may be a superstrate body, such as a glass pane. The transparent layer may also be a coating, such as an epoxy coating, a thermoplastic coating, or other organic-based coatings. 
     In some embodiments, like electrochromic devices  200  and  400 , electrochromic device  500  can further include a power distribution circuit electrically coupled to the transparent conductive layers  506  and  510  and the patterned conductive layers  512  and  522 . In such embodiments, the power distribution circuit is configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells  516 . The power distribution circuit may have an electrical power source coupled thereto. In some embodiments, the power distribution circuit includes an electrical switch. In these embodiments, the electrical switch is configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells  516 . This regulation may include selectively applying voltages to individual electrochromic cells  516  in order to produce patterns of transmissive states across the electrochromic device  500 . Non-limiting examples of patterns include gradients in shading, step-contrasts between shaded and non-shaded regions, and shading that defines informational characters (e.g., text). Other types of patterns of transmissive states are possible. 
     Although the illustrative embodiments describe the electrochromic devices as being incorporated into windows, the electrochromic device can be incorporated into other transparent panels. For example, by way of illustration without intending to be limiting, the electrochromic device can be incorporated in the glass covers for portable electronic devices or other devices. 
     According to an illustrative embodiment, a method of manufacturing an electrochromic device includes forming an optically active layer onto a first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field. The first transparent conductive layer is disposed on a portion of a transparent substrate. The method also includes depositing a second transparent conductive layer onto the optically active layer and patterning a conductive material into an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. In some embodiments, the method further involves bonding a transparent superstrate to the array of patterned conductive material. In some embodiments, the optically active layer includes an electrochromic layer, an ion conductive layer, and an ion storage layer. 
     In some embodiments, patterning the conductive material into the array includes manipulating a precursor fluid onto the second transparent conductive layer using a process selected from the group consisting of rotogravure printing, ink-jet printing, screen-printing, and stamping. 
     In some embodiments, patterning the conductive material into the array can include coating a photoresist layer onto the second transparent conductive layer. The patterning the conductive material into the array can also include exposing a portion of the photoresist layer to an electromagnetic radiation. The portion corresponds to a configuration of the array. Patterning the conductive material into the array can also involve removing, after exposure to the electromagnetic radiation, the portion. Such removal can define an opening through the photoresist layer. The patterning the conductive material into the array additionally involves depositing the conductive material onto the second transparent conductive layer through the opening and removing an unexposed portion of the photoresist layer from the second transparent conductive layer. In further embodiments, exposing the portion of the photoresist layer can include receiving a beam of electromagnetic radiation from a laser writing system. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings

Metadata:
Filing Date: 20160920
Publication Date: 20180410
Grant Date: 20180410
Priority Date: 20150929
Inventors: Nguyen Que Anh S.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/163", "inventive": false, "first": false, "tree": "[]"}, {"code": "B05D3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/134309", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/155", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/153", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/155", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F2001/1555", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/153", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/153", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2001/1555", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/155", "inventive": true, "first": true, "tree": "[]"}, {"code": "B05D3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/134309", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61801491