PATENT DOCUMENT

Publication Number: US-9490446-B2
Application Number: US-201414498844-A
Country: US
Kind Code: B2

Title: Organic light-emitting diode display with split anodes

Abstract:
An organic light-emitting diode display may have thin-film transistor circuitry formed on a substrate. A pixel definition layer may be formed on the thin-film transistor circuitry. Openings in the pixel definition layer may be provided with emissive material overlapping split anodes that are separated by anode gaps. The anode gaps may extend vertically and horizontally or may extend diagonally. The pixel definition layer openings may have edges that extend vertically and horizontally or that extend diagonally. A display may have three different pixel colors or may have four different pixel colors. Each pixel definition layer opening may have a pair of split anodes that are overlapped by a common layer of emissive material or may have four split anodes that are overlapped by a common layer of emissive material.

Claims:
What is claimed is: 
     
       1. An organic light-emitting diode display, comprising:
 a substrate; 
 a layer of thin-film transistor circuitry on the substrate; and 
 a pixel definition layer on the layer of thin-film transistor circuitry, wherein the pixel definition layer has a first set of openings each of which contains an organic emissive layer for multiple organic light-emitting diodes and has multiple corresponding split anodes, wherein each of the multiple split anodes in each opening in the first set of openings is associated with a respective pixel and is separated from another one of the multiple split anodes in that opening by an anode gap, wherein the pixel definition layer has a second set of openings each of which contains an organic emissive layer for a single organic light-emitting diode and a single anode that is associated with a respective green pixel, and wherein the green pixels do not have split anodes. 
 
     
     
       2. The organic light-emitting diode display defined in  claim 1 , wherein the green pixels are horizontally aligned. 
     
     
       3. The organic light-emitting diode display defined in  claim 2  wherein the pixels include blue pixels and red pixels, wherein the first set of openings in the pixel definition layer includes blue pixel definition layer openings each of which contains a pair of the split anodes for a pair of blue pixels, and wherein the first set of openings in the pixel definition layer includes red pixel definition layer openings each of which contains a pair of the split anodes for a pair of red pixels. 
     
     
       4. The organic light-emitting diode display defined in  claim 3  wherein the blue pixel definition layer openings and the red pixel definition layer openings alternate along a vertical column. 
     
     
       5. The organic light-emitting diode display defined in  claim 1 , wherein the pixels include horizontally aligned red pixels each of which is formed in a respective red pixel definition layer opening. 
     
     
       6. The organic light-emitting diode display defined in  claim 5  wherein the pixels include blue pixels, wherein first set of openings in the pixel definition layer includes blue pixel definition layer openings each of which contains a pair of the split anodes for a pair of blue pixels. 
     
     
       7. The organic light-emitting diode display defined in  claim 6  wherein the red pixel definition layer openings and the blue pixel definition layer openings alternate along a vertical column. 
     
     
       8. The organic light-emitting diode display defined in  claim 1 , wherein the pixels include horizontally aligned blue pixels each of which is formed in a respective blue pixel definition layer opening in the pixel definition layer. 
     
     
       9. The organic light-emitting diode display defined in  claim 8  wherein the pixels include red pixels and green pixels, wherein the first set of openings in the pixel definition layer includes red pixel definition layer openings each of which contains a pair of the split anodes for a pair of red pixels. 
     
     
       10. The organic light-emitting diode display defined in  claim 9  wherein the red pixel definition layer openings and the green pixel definition layer openings alternate along a vertical column. 
     
     
       11. The organic light-emitting diode display defined in  claim 1  wherein the first set of openings in the pixel definition layer includes blue pixel definition layer openings each of which contains a pair of the split anodes for a pair of blue pixels, wherein the anode gap splitting the anodes for the pair of blue pixels in each blue pixel definition layer opening extends vertically. 
     
     
       12. The organic light-emitting diode display defined in  claim 11  wherein the first set of openings in the pixel definition layer includes red pixel definition layer openings each of which contains a pair of the split anodes for a pair of red pixels, wherein the anode gap splitting the anodes for the pair of red pixels in each red pixel definition layer opening extends vertically, and wherein the blue pixel definition layer openings and red pixel definition layer openings alternate along a column. 
     
     
       13. The organic light-emitting diode display defined in  claim 1  wherein the first set of openings in the pixel definition layer includes include blue pixel definition layer openings each of which contains a pair of the split anodes for a pair of blue pixels, wherein the anode gap splitting the anodes for the pair of blue pixels in each blue pixel definition layer opening extends vertically, wherein the blue pixel definition layer openings extend along columns, wherein the first set of openings in the pixel definition layer includes red pixel definition layer openings each of which contains a pair of the split anodes for a pair of red pixels, wherein the anode gap splitting the anodes for the pair of red pixels in each red pixel definition layer opening extends vertically, wherein the red pixel definition layer openings extend along columns. 
     
     
       14. An organic light-emitting diode display, comprising:
 a substrate; 
 a layer of thin-film transistor circuitry on the substrate; and 
 a pixel definition layer on the layer of thin-film transistor circuitry, wherein the pixel definition layer has first and second sets of pixel definition layer openings, each of which contains a pair of anodes split along an anode gap, wherein the anodes are coupled to transistors in the layer of thin-film transistor circuitry, wherein each pixel definition layer opening in the first and second sets contains an organic emissive layer that overlaps the pair of anodes and spans the anode gap, wherein the pixel definition layer further comprises a third set of pixel definition layer openings, each of which contains a single anode that is not split and an organic emissive layer that overlaps the single anode, and wherein the organic emissive layer in each of the pixel definition layer opening in the third set is a green organic emissive layer. 
 
     
     
       15. The organic light-emitting diode display defined in  claim 14 , wherein the organic emissive layers in the first and second sets of pixel definition layer openings include red, light blue, and dark blue organic emissive layers. 
     
     
       16. A light-emitting diode display, comprising:
 a substrate; 
 a layer of thin-film transistor circuitry on the substrate; and 
 a pixel definition layer on the layer of thin-film transistor circuitry, wherein the pixel definition layer comprises blue pixel definition layer openings, red pixel definition layer openings, and green pixel definition layer openings, wherein each of the blue pixel definition layer openings contains a blue emissive layer that overlaps a pair of split anodes, wherein each of the red pixel definition layer openings contains a red emissive layer that overlaps a pair of split anodes, and wherein the green pixel definition layer openings do not contain split anodes. 
 
     
     
       17. The light-emitting diode display defined in  claim 16 , wherein each of the green pixel definition layer openings contains a green emissive layer that overlaps a single anode. 
     
     
       18. The light-emitting diode display defined in  claim 16 , wherein the blue pixel definition layer openings are horizontally aligned. 
     
     
       19. The light-emitting diode display defined in  claim 16 , wherein the red pixel definition layer openings are horizontally aligned. 
     
     
       20. The light-emitting diode display defined in  claim 16 , wherein the green pixel definition layer openings are horizontally aligned. 
     
     
       21. The organic light-emitting diode display defined in  claim 16 , wherein the pairs of split anodes in each of the blue pixel definition layer openings and each of the red pixel definition layer openings are separated by a respective horizontally-extending anode gap. 
     
     
       22. The organic light-emitting diode display defined in  claim 16 , wherein the pairs of split anodes in each of the blue pixel definition layer openings and each of the red pixel definition layer openings are separated by a respective vertically-extending anode gap. 
     
     
       23. The organic light-emitting diode display defined in  claim 16 , wherein the blue pixel definition layer openings and the red pixel definition layer openings are horizontally aligned and alternate along a vertical column.

Description:
This application claims the benefit of provisional patent application No. 62/012,907 filed Jun. 16, 2014, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to displays, and more particularly, to organic light-emitting diode displays. 
     Electronic devices often include displays. Organic light-emitting diode displays may exhibit desirable attributes such as a wide field of view, compact size, and low power consumption. Some organic light-emitting diodes use a tandem design in which a color filer array is used to impart colors to an array of white organic light-emitting diodes. Displays with this type of design experience light losses as white light from the light-emitting diodes passes through the color filter elements of the color filter array. 
     Organic light-emitting diode displays with individually colored light-emitting diodes (e.g. red, green, and blue diodes) may offer improved efficiency. To form displays such as these, organic emissive material (e.g., red, green, and blue emissive layers) may be evaporated onto a display substrate through a shadow mask. A dielectric pixel definition layer is formed over a thin-film transistor layer on the display substrate. The pixel definition layer has an array of openings that overlap anodes for the light-emitting diodes. The organic emissive materials are evaporated into openings in the pixel definition layer. At higher display resolutions, the portions of the pixel definition layer that surround the openings consume increasing amounts of surface area relative to the anodes. This limits the aperture ratio of the pixels and thereby limits display performance. 
     It would therefore be desirable to be able to provide improved displays such as improved organic light-emitting diode displays. 
     SUMMARY 
     An electronic device may include a display having an array of organic light-emitting diode display pixels. The display may have a display substrate and thin-film transistor circuitry formed on the substrate. 
     A pixel definition layer may be formed on the thin-film transistor circuitry. Openings in the pixel definition layer may be provided with emissive material that overlaps split anodes. The split anodes are separated by anode gaps. 
     Anode gaps may extend vertically and horizontally or may extend diagonally across the display. The pixel definition layer openings may have edges that extend vertically and horizontally or that extend diagonally. 
     A display may have three different pixel colors. For example, a display may have red, green, and blue pixels. A display may also have four different pixel colors (e.g., light blue, dark blue, red, and green). Some of the pixel colors may have split anodes and other pixel colors may have anodes that are not split. 
     Each pixel definition layer opening that is associated with split anodes may have a pair of split anodes that are overlapped by a common layer of emissive material or may have four split anodes that are overlapped by a common layer of emissive material. The split anodes are independently controlled by independent pixel circuits in the thin-film transistor circuitry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 2  is a diagram of an illustrative organic light-emitting diode pixel circuit in accordance with an embodiment. 
         FIG. 3  is a diagram of an illustrative organic light-emitting diode display in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of a portion of an illustrative organic light-emitting diode display in accordance with an embodiment. 
         FIG. 5  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form a column of openings with split anode structures for red and blue pixels in accordance with an embodiment. 
         FIG. 6  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form a column of openings with split anode structures for green and blue pixels in accordance with an embodiment. 
         FIG. 7  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form a column of openings with split anode structures for red and green pixels in accordance with an embodiment. 
         FIG. 8  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form rows of openings with split anode structures for red and blue pixels in an arrangement with green pixels that are laterally offset from one another in alternating rows in accordance with an embodiment. 
         FIG. 9  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form rows of openings with split anode structures for red and blue pixels in an arrangement with columns of laterally aligned green pixels in accordance with an embodiment. 
         FIG. 10  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form openings with four split anodes for red, green, and blue pixels in accordance with an embodiment. 
         FIG. 11  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form openings with horizontally and vertically split anode structures for pixels of four different colors in accordance with an embodiment. 
         FIG. 12  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer May be patterned to form openings with diagonal edges and split anode structures for pixels of four different colors with in accordance with an embodiment. 
         FIG. 13  is a top view of a portion of an illustrative organic light-emitting diode display showing how a pixel definition layer may be patterned to form openings with horizontal and vertical edges and diagonally split anode structures for pixels of four different colors in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with an organic light-emitting diode display is shown in  FIG. 1 . As shown in  FIG. 1 , electronic device  10  may have control circuitry  16 . Control circuitry  16  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  16  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  12  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  12  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones speakers, tone generators, vibrators cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  12  and may receive status information and other output from device  10  using the output resources of input-output devices  12 . 
     Input-output devices  12  may include one or more displays such as display  14 . Display  14  may be a touch screen display that includes a touch sensor for gathering touch input from a user or display  14  may be insensitive to touch. A touch sensor for display  14  may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. 
     Control circuitry  16  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  16  may display images on display  14 . 
     Display  14  may be an organic light-emitting diode display. In an organic light-emitting diode display, each display pixel contains a respective organic light-emitting diode. A schematic diagram of an illustrative pixel circuit for an organic light-emitting diode display pixel is shown in  FIG. 2 . As shown in  FIG. 2 , display pixel  22  may include light-emitting diode  38 . A positive power supply voltage ELVDD may be supplied to positive power supply terminal  34  and a ground power supply voltage ELVSS may be supplied to ground power supply terminal  36 . Diode  38  has an anode (terminal AN) and a cathode (terminal CD). The state of drive transistor  32  controls the amount of current flowing through diode  38  and therefore the amount of emitted light  40  front display pixel  22 . Cathode CD of diode  38  is coupled to ground terminal  36 , so cathode terminal CD of diode  38  may sometimes be referred to as the ground terminal for diode  38 . Cathode CD may be shared among multiple diodes (i.e., the cathodes CD of multiple diodes may be tied to a shared voltage). The voltage on the anode of each diode is independently controlled to control the amount of light the diode produces for the pixel associated with that diode. 
     To ensure that transistor  38  is held in a desired state between successive frames of data, display pixel  22  may include a storage capacitor such as storage capacitor Cst. The voltage on storage capacitor Cst is applied to the gate of transistor  32  at node A to control transistor  32 . Data can be loaded into storage capacitor Cst using one or more switching transistors such as switching transistor  30 . When switching transistor  30  is off, data line D is isolated from storage capacitor Cst and the gate voltage on terminal A is equal to the data value stored in storage capacitor Cst (i.e., the data value from the previous frame of display data being displayed on display  14 ). When gate line G (sometimes referred to as a scan line) in the row associated with display pixel  22  is asserted, switching transistor  30  will be turned on and a new data signal on data line D will be loaded into storage capacitor Cst. The new signal on capacitor Cst is applied to the gate of transistor  32  at node A, thereby adjusting the state of transistor  32  and adjusting the corresponding amount of light  40  that is emitted by light-emitting diode  38 . If desired, the circuitry for controlling the operation of light-emitting diodes for display pixels in display  14  (e.g., transistors, capacitors, etc. in display pixel circuits such as the display pixel circuit of  FIG. 2 ) may be formed using other configurations (e.g., configurations that include circuitry for compensating for threshold voltage variations in drive transistor  32 , etc.). The display pixel circuit of  FIG. 2  is merely illustrative. 
     As shown in  FIG. 3 , display  14  may include layers such as substrate layer  24 . Substrate  24  and, if desired, other layers in display  14 , may be formed from planar rectangular layers of material such as planar glass layers, planar polymer layers, composite films that include polymer and inorganic materials, metallic foils, etc. Substrate  24  may have left and right vertical edges and upper and lower horizontal edges. If desired, substrate  24  may have non-rectangular shapes (e.g., shapes with curved edges, etc.). 
     Display  14  may have an array of display pixels  22  for displaying images for a user. Each display pixel may have a light-emitting diode such as organic light-emitting diode  38  of  FIG. 2  and associated thin-film transistor circuitry (e.g., the pixel circuit of  FIG. 2  or other suitable display pixel circuit). The array of display pixels  22  may be formed from rows and columns of display pixel structures (e.g., display pixels formed from structures on display layers such as substrate  24 ). There may be any suitable number of rows and columns in the array of display pixels  22  (e.g., ten or more, one hundred or more or one thousand or more). Display  14  may include display pixels  22  of different colors. As an example, display  14  may include red pixels that emit red light, green pixels that emit green light, and blue pixels that emit blue light. Display  14  may also include pixels of four different colors (e.g., light blue, dark blue, red, and green). Configurations for display  14  that include display pixels of other colors may be used, if desired. 
     Display driver circuitry may be used to control the operation of pixels  22 . The display driver circuitry may be formed from integrated circuits, thin-film transistor circuits, or other suitable circuitry. As shown in  FIG. 3 , display driver integrated circuit  28  (sometimes referred to as a timing controller chip) may contain communications circuitry for communicating with system control circuitry over path  26 . Path  26  may be formed from traces on a flexible printed circuit or other cable. The control circuitry may be located on one or more printed circuits in electronic device  10 . During operation, the control circuitry (e.g., control circuitry  16  of  FIG. 1 ) may supply circuitry such as display driver integrated circuit  28  with information on images to be displayed on display  14 . Circuits such as display driver integrated circuits may be mounted on substrate  24  or may be coupled to substrate  24  through a flexible printed circuit cable or other paths. The circuitry of display driver integrated circuits such as circuit  28  may also be provided using thin-film transistor circuitry on substrate  24 . 
     To display the images on display pixels  22 , display driver circuitry  28  may supply corresponding image data to data lines D while issuing clock signals and other control signals to supporting display driver circuitry such as gate driver circuitry  18  and demultiplexing circuitry  20 . 
     Demultiplexer circuitry  20  may be used to demultiplex data signals from circuit  28  onto a plurality of corresponding data lines D. With the illustrative arrangement of  FIG. 3 . data lines D run vertically through display  14 . Data lines D are associated with respective columns of display pixels  22 . Demultiplexer circuitry  20  may be implemented as part of an integrated circuit such as circuit  28  and/or may be formed from thin-film transistor circuitry on substrate  24 . 
     Gate driver circuitry  18  (sometimes referred to as scan line driver circuitry) may be implemented as part of an integrated circuit such as circuit  28  and/or may be implemented using thin-film transistor circuitry on substrate  24 . Gate lines G (sometimes referred to as scan lines) run horizontally through display  14 . Each gate line G is associated with a respective row of display pixels  22 . If desired, there may be multiple horizontal control lines such as gate lines G associated with each row of display pixels. Gate driver circuitry  18  may be located on the left side of display  14 , on the right side of display  14 , or on both the right and left sides of display  14 , as shown in  FIG. 3 . 
     Gate driver circuitry  18  may assert horizontal control signals (sometimes referred to as scan signals or gate signals) on the gate lines G in display  14 . For example, gate driver circuitry  18  may receive clock signals and other control signals from circuit  28  and may, in response to the received signals, assert a gate signal on gate lines G in sequence, starting with the gate line signal G in the first row of display pixels  22 . As each gate line is asserted, data from data lines D is located into the corresponding row of display pixels. In this way, control circuitry such as display driver circuitry  28 ,  20 , and  18  may provide display pixels  22  with signals that direct display pixels  22  to generate light for displaying a desired image on display  14 . If desired, more complex control schemes may be used to control display pixels using multiple thin-film transistors (e.g., to implement threshold voltage compensation schemes). 
     Display circuits such as demultiplexer circuitry  20 , gate line driver circuitry  18 , and the circuitry of display pixels  22  may be formed using thin-film transistors on substrate  24  such as silicon-based transistors such as polysilicon thin-film transistors, semiconducting-oxide-based transistors such as InGaZnO transistors, or other thin-film transistor circuitry. 
     A cross-sectional side view of a configuration that may be used for the pixels of display  14  of device  10  is shown in  FIG. 4 . As shown in  FIG. 4 , display  14  may have a substrate such as substrate  24 . Thin-film transistors, capacitors, and other thin-film transistor circuitry  50  (e.g., display pixel circuitry such as the illustrative display pixel circuitry of  FIG. 2 ) may be formed on substrate  24 . In the illustrative portion of display  14  that is shown in  FIG. 4 , two organic light-emitting diodes  38  (e.g., left-hand diode  38 - 1  and right-hand diode  38 - 2 ) have been formed on substrate  24  and provide independently controlled amounts of light  40  for two respective display pixels  22  (e.g., a left-hand display pixel  22  and a right-hand display pixel  22 ). 
     Organic light-emitting diodes such as organic light-emitting diodes  38  may be formed from anodes in thin-film transistor circuitry  50  such as anodes  58 . Anodes  58  are formed from a commonly deposited conductive layer that is split along anode gap  70  and may therefore sometimes be referred to as split anodes. Anodes  58  may be formed from metal that is photolithographically patterned. The size of anode gap  70  may therefore be relatively small (e.g., 5-12 microns, less than 15 microns, less than 12 microns, less than 10 microns, or more than 4 microns, as examples). The close spacing that is possible between split anodes  58  helps allow display resolution to be enhanced without excessive reductions in pixel aperture ratio. 
     A blanket cathode layer such as cathode layer  60  may cover all of the display pixels in display  14 . Cathode layer  60  may be formed from a transparent conductive material such as indium tin oxide and/or a layer of metal that is sufficiently thin to allow light  40  from diodes  38 - 1  and  38 - 2  to pass. 
     Each diode  38  may have an organic light-emitting emissive layer (sometimes referred to as emissive material or an emissive layer structure). The emissive layer is an electroluminescent organic layer that emits light  40  in response to applied current through each diode  38 . A common layer of emissive material such as emissive layer  56  may cover (overlap) both of split anodes  58  and may span anode gaps such as anode gap  70  that lie between the split anodes. The organic emissive material in gap  70  has a high resistance, so diodes  38 - 1  and  38 - 2  are electrically isolated from each other and may be operated independently. 
     As shown in  FIG. 4 , emissive layer portion  56 - 1  of layer  56  overlaps the left-hand anode  58  of  FIG. 4  and emits light  40  for a left-hand pixel  22  in response to current applied by diode  38 - 1  between left-hand anode  58  and cathode  60 . Emissive layer portion  56 - 2  of layer  56  overlaps the right-hand anode  58  of  FIG. 4  and emits light  40  for a right-hand pixel  22  in response to current applied by diode  38 - 2  between right-hand anode  58  and cathode  60 . 
     In a color display, emissive layers  56  in the array of pixels in the display include emissive materials of different color. Emissive layer  56  may be deposited on anodes  58  by evaporating layer  56  through a shadow mask (sometimes referred to as a fine metal mask). A slit mask or a spot mask may be used depending on the layout of the pixel colors across the surface of display  14 . For example, in configurations in which pixels of the same color are arranged in a horizontally aligned fashion in vertically extending columns, slit masks may be used. 
     In a display with red, green, and blue pixels, red emissive layers are used for emitting red light in red pixels, green emissive layers are used for emitting green light in green pixels, and blue emissive layers are used for emitting blue light in blue pixels. In a display with four colors such as light blue, blue, green, and red, there are four correspondingly colored emissive layers for emitting light blue light, blue light (sometimes called dark blue light), green light, and red light. Displays with other patterns of colored pixels may have colored emissive layers with correspondingly patterns. 
     When an emissive layer such as emissive layer  56  of  FIG. 4  overlaps multiple split anodes (i.e., a pair of split anodes  58  in the example of  FIG. 4  or more than two anodes in other split anode configurations), each of the associated diodes  38  in the set of diodes associated with the split anodes produces light of the same color. For example, if emissive layer  56  of  FIG. 4  is a red emissive layer, both left-hand diode  38 - 1  and right-hand diode  38 - 2  will produce red light. The amount of light that is produced by each diode can be independently adjusted (i.e., pixels  22  form a pair of independently adjustable red pixels in this example). Diodes of other colors can be formed by evaporating emissive material of different colors onto other anodes in display  14 . 
     In addition to the emissive organic layer in each diode  38 , each diode  38  may include additional layers for enhancing diode performance such as an electron injection layer, an electron transport layer, a hole transport layer, and a hole injection layer. Layers such as these may be formed from organic materials (e.g., materials on the upper and lower surfaces of electroluminescent material in layer  56 ). 
     Layer  52  (sometimes referred to as a pixel definition layer) has an array of openings such as opening  54  in which emissive material structures such as layer  56  of  FIG. 4  are formed and in which anodes  58  for diodes  38  are located. Some pixel definition layer openings may contain split anodes  58 , as shown in  FIG. 4 . Other pixel definition laser openings (e.g., openings for pixels of different colors) may contain only a single anode. 
     Pixel definition layer  52  may be formed from a photoimageable material that is photolithographically patterned (e.g., dielectric material that can be processed to form photolithographically defined openings such as photoimageable polyimide, photoimageable polyacrylate, other organic photoimageable materials, etc.) or may be formed from material that is deposited through a shadow mask (as examples). 
     When using a split anode arrangement, openings  54  in pixel definition layer  52  may be sized appropriately to allow two or more pixels to be formed from the two or more split anodes  58  in that opening. For example, each opening  54  may contain two split anodes for two pixels  22 , may contain three split anodes for three pixels  22 , may contain four split anodes for four pixels  22 , may contain two or more split anodes, may contain two to four split anodes, or may form more than four split anodes for more than four pixels  22 . The width of gaps such as anode-splitting gap  70  of  FIG. 4  may be narrower than the widths of the portions of pixel definition layer  52  between respective openings  54 , so the use of split anodes  58  in display  14  may help minimize the fraction of display surface area that is consumed by pixel definition layer  52  and thereby enhance pixel aperture ratios for pixels  22 . 
     Anode-splitting gaps  70  may be formed for each pixel color or for only a subset of pixel colors in display  14 . Gaps  70  may extend vertically, horizontally, and/or diagonally. 
     Consider, as an example, the illustrative pixel layout of display  14  in  FIG. 5 . In the example of  FIG. 5 , pixel definition layer  52  has openings  54  associated with green, red, and blue pixels  22 . “Green” pixel definition layer openings  54  are each used for forming a respective green pixel G. “blue” pixel definition layer openings  54  are each used for forming a respective pair of blue pixels B 1  and B 2 , and “red” pixel definition layer openings  54  are each used for forming a respective pair of red pixels R 1  and R 2 . In each blue pixel definition layer opening  54 , an anode gap  70  (i.e., a blue anode gap) is used to separate a pair of anodes  58  for respective blue pixels B 1  and B 2 . In each red pixel definition layer opening  54 , an anode gap  70  (i.e., a red anode gap) may separate a pair of anodes  58  for respective red pixels R 1  and R 2 . Green pixels G in the arrangement of  FIG. 5  do not have split anodes. Each green pixel definition layer opening  54  is associated with a single respective green pixel anode. 
     The pattern of  FIG. 5  (and the patterns of the illustrative displays in the other FIGS.) extends in a tiled fashion across all of display  14 . As shown in  FIG. 5 , green pixels G may be arranged in columns and may be horizontally aligned (i.e., green pixels G in each column may have the same location along horizontal dimension X), facilitating fabrication using a slit mask. Red and blue pixels may be arranged in columns so that pairs of red pixels R 1  and R 2  alternate with pans of blue pixels B 1  and B 2 . Anode gaps  70  in the  FIG. 5  arrangement all extend horizontally (i.e., each gap  70  runs parallel to horizontal axis X). 
     In the illustrative configuration of  FIG. 6 , horizontally extending green anode gaps  70  are used to split the anodes  58  for green pixels G 1  and G 2  in each green pixel definition layer opening  54  in pixel definition layer  52  and horizontally extending blue anode gaps  70  are used to split the anodes  58  for blue pixels B 1  and B 2  in each blue pixel definition layer opening  54  in pixel definition layer  52 . Red pixels R are horizontally aligned and are arranged in columns running parallel to vertical dimension Y. Red pixels R each have a single anode and do not have split anodes. Blue pixel definition layer openings  54  and green pixel definition layer openings  54  are horizontally aligned and are arranged in columns. In each column, blue pixel pairs B 1 /B 2  alternate with green pixel pairs G 1 /G 2  along vertical dimension Y. 
     In the illustrative configuration of  FIG. 7 . horizontally extending red anode gaps  70  are used to split the anodes  58  for red pixels R 1  and R 2  in each red pixel definition layer opening  54  in pixel definition layer  52  and horizontally extending green anode gaps  70  are used to split the anodes  58  for green pixels G 1  and G 2  in each green pixel definition layer opening  54  in pixel definition layer  52 . Blue pixels B are horizontally aligned with each other and are arranged in columns running parallel to vertical dimension Y. Blue pixels B each have a single anode and do not have split anodes. Red pixel definition layer openings  54  and green pixel definition layer openings  54  are horizontally aligned and are arranged in columns. In each column, the red and green openings alternate, so that red pixel pairs R 1 /R 2  alternate with green pixel pairs G 1 /G 2  along vertical dimension Y. 
       FIGS. 8 and 9  are illustrative pixel patterns that may be used for a display with vertically extending anode gaps  70 . 
     In the illustrative arrangement of  FIG. 8 , vertically extending blue anode gaps  70  are used to split the anodes  58  for blue pixels B 1  and B 2  in each blue pixel definition layer opening  54  in pixel definition layer  52 . Vertically extending red anode gaps  70  are used to split the anodes  58  for red pixels R 1  and R 2  in each red pixel definition layer opening  54  in pixel definition layer  52 . Red pixel pairs R 1 /R 1  are horizontally aligned with blue pixel pairs B 1 /B 2  and are arranged in columns in which the red pixel pairs R 1 /R 2  alternate with blue pixel pairs B 1 /B 2 . Green pixels G have different horizontal positions in dimension X in alternating rows. 
     In the illustrative arrangement of  FIG. 9 , vertically extending blue anode gaps  70  are used to split the anodes  58  for blue pixels B 1  and B 2  in each blue pixel definition layer opening  54  in pixel definition layer  52 . Vertically extending red anode gaps  70  are used to split the anodes  58  for red pixels R 1  and R 2  in each red pixel definition layer opening  54  in pixel definition layer  52 . Red pixel pairs R 1 /R 1  are horizontally aligned and are arranged in columns. Blue pixel pairs B 1 /B 2  and are horizontally aligned and are arranged in columns. Green pixels G, which do not have split anodes, are also horizontally aligned with each other and are arranged in columns. Because each color of pixel is aligned in a respective column, the pattern of  FIG. 9  may be formed using a shadow mask with vertically extending slits (sometimes referred to as a slit mask). Spot masks may be used whenever horizontally aligned and vertically extending columns of pixels of the same color are not present in a display. 
       FIG. 10  is a top view of an illustrative display in which vertically and horizontally extending blue anode gaps  70  are used to split the anodes  58  in each blue pixel definition layer opening into four blue pixels B 1 , B 2 , B 3 , and B 4 . Blue pixels extend in columns and may be formed with a slit mask. Vertically and horizontally extending red anode gaps  70  are used to split the anodes  58  in each red pixel definition layer opening into four red pixels R 1 , R 2 , R 3 , and R 4 . Vertically and horizontally extending green anode gaps  70  are used to split the anodes  58  in each green pixel definition layer opening into four green pixels G 1 , G 2 , G 3 , and G 4 . The green and red pixels may be formed using spot shadow masks. 
     If desired, display pixels  40  may have tour colors. As an example, display pixels  40  may include light blue pixels (sometimes referred to as sky blue pixels), dark blue pixels (sometimes referred to as blue pixels), red pixels, and green pixels. The use of these four colors for pixels  22  may allow display  14  to produce light  40  with a desired color gamut. The presence of the light blue pixels may allow display  14  to produce light colors without overly stressing the blue pixels, therefore extending display lifetime. In the illustrative arrangement of  FIG. 11 , vertically extending and horizontally extending light blue anode gaps  70  are used to split anodes  58  in each light blue pixel definition layer opening into four respective anodes for four respective light blue pixels LB 1 , LB 2 , LB 3 , and LB 4 . Vertically extending and horizontally extending dark blue anode gaps  70  are used to split anodes  58  in each dark blue pixel definition layer opening into four respective anodes for four respective dark blue pixels B 1 , B 2 , B 3 , and B 4 . Vertically extending and horizontally extending red anode gaps  70  are used to split anodes  58  in each red pixel definition layer opening into four respective anodes for four respective red pixels R 1 , R 2 , R 3 , and R 4 . Vertically extending and horizontally extending green anode gaps  70  are also used to split anodes  58  in each green pixel definition layer opening into four respective anodes for four respective green pixels G 1 , G 2 , G 3 , and G 4 . 
     The illustrative configurations of  FIGS. 12 and 13  include diagonal structures and can be controlled using display control circuitry that supplies control signals on horizontal, vertical, and/or diagonal signal lines in display  14 . 
       FIG. 12  is a top view of a portion of an illustrative display showing how pixel definition layer  52  may be patterned to form openings  54  with diagonal edges. Each opening may contain two split anodes (for a pair of red pixels R 1 /R 2 , a pair of dark blue pixels B 1 /B 2 , a pair of light blue pixels LB 1 , LB 2 , or a pair of green pixels G 1 /G 2 ). Anode gaps  70  extend horizontally and vertically. 
       FIG. 13  is a top view of a portion of an illustrative display in which pixel definition layer  52  has been patterned to form openings  54  with horizontal and vertical edges. Each opening may contain two split anodes (for a pair of red pixels R 1 /R 2 , a pair of dark blue pixels B 1 /B 2 , a pair of light blue pixels LB 1 , LB 2 , or a pair of green pixels G 1 /G 2 ). Anode gaps  70  of  FIG. 13  extend diagonally. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140926
Publication Date: 20161108
Grant Date: 20161108
Priority Date: 20140616
Inventors: LEE JUNGMIN
LEE CHOONGHO
KIM JINKWANG
Assignee: APPLE INC
CPC Classifications: [{"code": "H01L27/3218", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3216", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/3211", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L33/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/3246", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/3213", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L51/5209", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L33/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10H20/831", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10H20/83", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/353", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/353", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/122", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/351", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/352", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/352", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K50/813", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/122", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/351", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/35", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/80515", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54836914