Multicolor OLED arrays for high aperture displays

Abstract

A microcavity pixel design and fabrication method for an organic light emitting diode (OLED) array with a high aperture ratio suitable for light field displays. This is achieved by laterally overlapping intermediate electrodes and optical filler layers and reducing the lateral spacing. The OLED layers in the design have a uniform white OLED stack, allowing each layer to be deposited across the entire OLED array, simplifying fabrication. The optical path length in the optical microcavity of each subpixel is optimized by the thickness of the optical filler layer, allowing the white OLED stack to be uniform, reducing fabrication complexity.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 17 / 378,300, filed July 16, 2021, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to patterning designs and fabrication methods for organic light-emitting diode (OLED) devices with high aperture ratios suitable for light field displays. [Background technology]

[0003] Light field displays offer multiple fields of view, allowing the user to receive a separate view with each eye. Current displays in this category offer interesting viewing experiences, but an appealing light field display requires very high pixel density, very low angular separation between views, and a large viewing angle. It is desirable for the user to experience a smooth transition between viewing zones while maintaining a perceptible view that is independent from adjacent views. A fundamental requirement in achieving these viewing parameters is control of the output characteristics of the radiation source. Organic light-emitting diodes (OLEDs) coupled within a microcavity allow for control of the spectral bandwidth and output angle of the resulting light.

[0004] One way to control the light output characteristics is through the use of a microcavity. A microcavity is formed between two mirrors or reflective surfaces and can be, for example, a layered stack of non-absorbing materials, which can be a metal anode, a metal cathode, or a distributed Bragg reflector (DBR). The mirrors generally serve to reflect light over a certain wavelength range while preserving the physical properties of the incident light. Two main design variables that affect the output characteristics of a microcavity are the reflectivities of the top and bottom surfaces (i.e., the opposing mirrors) and the optical path length Λ. The wavelength of light output by such an OLED structure depends in part on the optical path length of the microcavity. The optical path length can be manipulated by adjusting the thickness and / or number of layers that make up the microcavity.

[0005] Fabricating OLEDs suitable for light field displays presents challenges when depositing the organic layers separately to achieve the thicknesses required for the desired optical path lengths of each color. One challenge in fabricating OLEDs suitable for light field displays is achieving a high aperture ratio with pixels smaller than 10 μm using available manufacturing capabilities. The pixel aperture ratio is the ratio of the pixel's emissive area to the total area of ​​the display. High aperture ratios can be achieved by maximizing the emissive area of ​​each pixel on the display. This reduces gaps in the display area and improves the image quality of light field displays. Achieving a high aperture ratio is particularly challenging when fabricating high-resolution displays with small pixel sizes.

[0006] U.S. Patent Application Publication No. 2021 / 0057670 to Wong et al. describes an array of light-emitting OLED pixels. The disclosed pixels use multiple transparent or substantially transparent dielectric layers over each anode. The thickness of the dielectric layers is designed to optimize the emission of light of the desired color for that pixel. A white OLED layer is formed in a single deposition step in the OLED array, and the lateral spacing between each anode results in a reduced aperture ratio.

[0007] Park et al., U.S. Patent No. 10,790,473, describes an OLED device designed to achieve a high aperture ratio. This is achieved by first connecting the anode reflective electrode and transparent electrode at the corners of the subpixel area. Each subpixel has a microcavity structure, minimizing the pixel-defining layer between the subpixels. The spacing between the subpixels is undesirable for light field displays because it does not maximize the display's light-emitting area.

[0008] High aperture ratios are desirable for near-eye displays, such as virtual reality (VR) displays, augmented reality (AR) displays, microdisplays, and light field displays. There remains a need for micron-sized OLED pixel array designs and fabrication methods that achieve high aperture ratios at high display resolutions suitable for light field displays.

[0009] This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. It is not necessarily intended, nor should it be construed, that any of the preceding information constitutes prior art against the present invention. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 0057670 [Patent Document 2] U.S. Patent No. 10,790,473 Summary of the Invention

[0011] An object of the present disclosure is to provide an optical microcavity pixel device comprising organic light-emitting diodes (OLEDs) and a photolithographic patterning method for achieving micron-sized pixels that, when patterned in an array, yield an aperture ratio of greater than 70%. Another object of the present disclosure is to provide a method of OLED array patterning capable of producing light field displays with a resolution of greater than 1,000 ppi (pixels per inch). The optical microcavity pixel array comprises a distributed Bragg reflector (DBR) on a substrate and two or more subpixels comprising a semitransparent or fully transparent electrode and a series of semitransparent or fully transparent optical filler layers. Another object of the present disclosure is to provide an optical microcavity pixel design structure in which the semitransparent or fully transparent electrodes disposed on the DBR have a lateral overlap to reduce lateral spacing, thereby increasing the aperture ratio of the light field display. The limitation, reduction, or elimination of the lateral spacing between colored electrodes can be achieved using a layered series of semi-transparent or fully transparent filler layers interposed between overlapping electrodes of the first and second colors, the second and third colors, the first and third colors, or any combination thereof. The thickness of the filler layers is designed to tune the optical cavity of each pixel, thereby dictating the color produced by the optical microcavity pixel device. Another object of the present disclosure is to provide a method for reducing the complexity of the manufacturing process for high aperture OLED arrays.

[0012] In one aspect, an organic light-emitting diode device is provided that includes a substrate, a distributed Bragg reflector (DBR) on the substrate, a first color electrode on the DBR that defines a first color microcavity, the first color electrode connected to the substrate through a first via, a first optical filler layer on the DBR adjacent to the first color electrode, a second optical filler layer on the first optical filler layer that partially overlaps the first color electrode in an overlapping region, a second color electrode on the second optical filler layer that defines a second color microcavity, the second color electrode connected to the substrate through a second via, a white organic light-emitting diode (OLED) stack on the first color electrode and the second color electrode, and a top electrode on the white OLED stack.

[0013] In one embodiment, the electrodes of the second color partially overlap the electrodes of the first color.

[0014] In other embodiments, the first color microcavity has a first color optical path length between the DBR and the top electrode through the first color electrode, and the second color microcavity has a second color optical path length between the DBR and the top electrode through the second color electrode.

[0015] In other embodiments, the optical path length of the first color and the optical path length of the second first color are adjusted to provide desired first color and second color pixels, respectively.

[0016] In other embodiments, the first and second optical filler layers comprise a transparent polymer.

[0017] In other embodiments, the first and second optical filler layers comprise a transparent inorganic dielectric.

[0018] In other embodiments, the device further comprises a pixel-defining layer that insulates the first color electrode from the second color electrode.

[0019] In other embodiments, the pixel defining layer comprises one or more of an inorganic insulating dielectric and an organic material.

[0020] In other embodiments, the substrate is a thin film transistor (TFT) substrate.

[0021] In another embodiment, the device further comprises a second DBR on the top electrode.

[0022] In other embodiments, the top electrode is the cathode and the bottom electrode is the anode.

[0023] In other embodiments, the top electrode is the anode and the bottom electrode is the cathode.

[0024] In another embodiment, the device further comprises, above the second color electrode and below the white OLED stack, a third optical filler layer on the first optical filler layer that defines a third color microcavity; a fourth optical filler layer on the third optical filler layer and partially overlapping the second color electrode; and a third color electrode on the fourth optical filler layer that partially overlaps the second color electrode and is connected to the substrate through a third via.

[0025] In another aspect, a method for manufacturing a multicolor microcavity organic light-emitting diode (OLED) array is provided, the method including: depositing a distributed Bragg reflector (DBR) on a substrate; depositing a first color electrode on the DBR that defines a first color microcavity, the first color electrode being connected to the substrate through a first via; depositing a first optical filler layer on the DBR adjacent to the first color electrode; depositing a second optical filler layer on the first optical filler layer that partially overlaps the first color electrode in an overlapping region; depositing a second color electrode on the second optical filler layer that defines a second color microcavity, the second color electrode being connected to the substrate through a second via; depositing a white organic light-emitting diode (OLED) stack on the first color electrode and the second color electrode; and depositing a top electrode on the white OLED stack.

[0026] In one embodiment of the method, a white OLED stack is deposited over the entire OLED array.

[0027] In other embodiments of the method, the white OLED stack is deposited using thermal evaporation, spin casting, or inkjet printing.

[0028] In another embodiment of the method, the top electrode is deposited using thermal evaporation or sputtering.

[0029] In another embodiment, the method further comprises depositing a pixel-defining layer that insulates the first color electrode from the second color electrode.

[0030] In other embodiments of the method, the pixel defining layer is deposited using sputtering, spin coating, thermal evaporation, chemical vapor deposition, atomic layer deposition, or spin casting.

[0031] In another embodiment, the method further comprises depositing a second DBR on the top electrode.

[0032] In other embodiments of the method, the first color electrode, the second color electrode, and the top electrode are deposited using sputtering, thermal evaporation, or spin coating.

[0033] In other embodiments of the method, the first and second optical filler layers are deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

[0034] In other embodiments of the method, the DBR is deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

[0035] In another embodiment, the method further includes, before depositing the white OLED stack, depositing a third optical filler layer selected for a third color on the first optical filler layer, where the third optical filler layer overlaps the electrode of the first color; depositing a fourth optical filler layer selected for the third color on the third optical filler layer, where the fourth optical filler layer overlaps the electrode of the second color; and depositing a series of electrodes of the third color on the fourth optical filler layer. [Brief explanation of the drawings]

[0036] These and other features of the present invention will become more apparent in the following detailed description, which refers to the accompanying drawings.

[0037] [Figure 1A] 1 illustrates one embodiment of a cross-sectional view of a two-color optical microcavity organic light-emitting diode (OLED) array according to the present disclosure.

[0038] [Figure 1B] 1B shows an enlarged view of the one-color optical microcavity OLED device described in FIG. 1A.

[0039] [Figure 1C] 1B shows an enlarged view of the two-color optical microcavity OLED device described in FIG. 1A.

[0040] [Figure 2] 1 illustrates another embodiment of a two-color optical microcavity OLED array according to the present disclosure including a pixel-defining layer (PDL).

[0041] [Figure 3A] 10 shows another embodiment of a two-color optical microcavity OLED array according to the present disclosure that includes an additional DBR deposited on the cathode.

[0042] [Figure 3B] 3B shows an enlarged view of the two-color optical microcavity OLED device described in FIG. 3A.

[0043] [Figure 4] 1 illustrates one embodiment of a cross section of a three-color optical microcavity OLED array according to the present disclosure.

[0044] [Figure 5] 1 illustrates another embodiment of a three-color optical microcavity OLED array according to the present disclosure including a PDL.

[0045] [Figure 6] 10 shows another embodiment of a three-color optical microcavity OLED array according to the present disclosure that includes an additional DBR deposited on the cathode.

[0046] [Figure 7] 1 illustrates one embodiment of the optical path from the TFT substrate to the emission of a two-color optical microcavity OLED array according to the present disclosure.

[0047] [Figure 8] 1 illustrates one embodiment of the optical path from the TFT substrate to the emission of a three-color optical microcavity OLED array according to the present disclosure.

[0048] [Figure 9] 1 shows a top view of one embodiment of light emission from a three-color optical microcavity OLED array according to the present disclosure.

[0049] [Figure 10A] 1 shows step 1 of the proposed two-color OLED array patterning process for depositing the DBR.

[0050] [Figure 10B] 10 shows step 2 of the proposed two-color OLED array patterning process to form vias for the first color electrodes through the DBR.

[0051] [Figure 10C]1 shows step 3 of the proposed two-color OLED array patterning process for depositing the first color electrode.

[0052] [Figure 10D] 1 shows step 4 of the proposed two-color OLED array patterning process for depositing photoresist.

[0053] [Figure 10E] 10 shows step 5 of the proposed two-color OLED array patterning process for the photolithography step, where the photoresist is partially removed by etching by partially exposing the embodiment to UV light.

[0054] [Figure 10F] 10 shows step 6 of the proposed two-color OLED array patterning process for depositing the first optical filler layer.

[0055] [Figure 10G] 10 shows step 7 of the proposed two-color OLED array patterning process for the photolithography step, which removes the first optical filler layer deposited on the photoresist by lifting off the remaining photoresist.

[0056] [Figure 10H] FIG. 10 shows a top view of step 7 of the proposed two-color OLED array patterning process.

[0057] [Figure 10I] 10 shows step 8 of the proposed two-color OLED array patterning process for depositing the second optical filler layer.

[0058] [Figure 10J] 10 shows step 9 of the proposed two-color OLED array patterning process to form vias for the second color electrode through the DBR, the first optical filler layer, and the second optical filler layer.

[0059] [Figure 10K] 1 shows step 10 of the proposed two-color OLED array patterning process for depositing the second color electrode.

[0060] [Figure 10L] FIG. 1 shows a top view of step 10 of the proposed two-color OLED array patterning process.

[0061] [Figure 10M] 1 shows step 11 of the proposed two-color OLED array patterning process for depositing a white OLED stack.

[0062] [Figure 10N] 12 shows step 12 of the proposed two-color OLED array patterning process for depositing a cathode as the top reflective surface to form the optical microcavities of the OLED array.

[0063] [Figure 11A] 1 shows step 1 of the proposed three-color OLED array patterning process for depositing the DBR.

[0064] [Figure 11B] 10 shows step 2 of the proposed three-color OLED array patterning process to form vias for the first color electrodes through the DBR.

[0065] [Figure 11C] 1 shows step 3 of the proposed three-color OLED array patterning process for depositing the first color electrode.

[0066] [Figure 11D] Figure 4 shows step 4 of the proposed three-color OLED array patterning process for depositing photoresist.

[0067] [Figure 11E]10 shows step 5 of the proposed three-color OLED array patterning process for the photolithography step, where the photoresist is partially removed by etching by partially exposing the embodiment to UV light.

[0068] [Figure 11F] 10 shows step 6 of the proposed three-color OLED array patterning process for depositing the first optical filler layer.

[0069] [Figure 11G] 10 shows step 7 of the proposed three-color OLED array patterning process for the photolithography step, which removes the first optical filler layer deposited on the photoresist by lifting off the remaining photoresist.

[0070] [Figure 11H] FIG. 10 shows a top view of step 7 of the proposed three-color OLED array patterning process.

[0071] [Figure 11I] 10 shows step 8 of the proposed three-color OLED array patterning process for depositing the second optical filler layer.

[0072] [Figure 11J] 10 shows step 9 of the proposed three-color OLED array patterning process to form vias for the second color electrode through the DBR, the first optical filler layer, and the second optical filler layer.

[0073] [Figure 11K] 1 shows step 10 of the proposed three-color OLED array patterning process for depositing the second color electrode.

[0074] [Figure 11L] FIG. 1 shows a top view of step 10 of the proposed three-color OLED array patterning process.

[0075] [Figure 11M] 11 shows step 11 of the proposed three-color OLED array patterning process for depositing photoresist.

[0076] [Figure 11N] 12 shows step 12 of the proposed three-color OLED array patterning process for a photolithography step in which the photoresist is partially removed by etching by partially exposing the embodiment to UV light.

[0077] [Figure 11O] 13 shows step 13 of the proposed three-color OLED array patterning process for depositing the third optical filler layer.

[0078] [Figure 11P] 14 shows step 14 of the proposed three-color OLED array patterning process for the photolithography step that removes the third optical filler layer deposited on the photoresist by lifting off the remaining photoresist.

[0079] [Figure 11Q] 10 shows step 15 of the proposed three-color OLED array patterning process for depositing the fourth optical filler layer.

[0080] [Figure 11R] 1 shows step 16 of the proposed three-color OLED array patterning process for forming vias for a third color electrode through the DBR, the first optical filler layer, the third optical filler layer, and the fourth optical filler layer.

[0081] [Figure 11S] 17 shows step 17 of the proposed three-color OLED array patterning process for depositing the third color electrode.

[0082] [Figure 11T]FIG. 1 shows a top view of step 17 of the proposed three-color OLED array patterning process.

[0083] [Figure 11U] 1 shows step 18 of the proposed three-color OLED array patterning process for depositing a white OLED stack.

[0084] [Figure 11V] 1 shows step 19 of the proposed three-color OLED array patterning process for depositing a cathode as the top reflective surface to form the optical microcavity of the OLED device. DETAILED DESCRIPTION OF THE INVENTION

[0085] definition Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0086] The use of the word "a" or "an" when used herein in conjunction with the term "comprising" can mean "one," but is also consistent with the meaning of "one or more," "at least one," and "one or more."

[0087] As used herein, the terms "comprising," "having," "including," and "containing," and grammatical variations thereof, are inclusive or open-ended and do not exclude additional, unrecited elements and / or method steps. The term "consisting essentially of," when used herein in connection with a composition, device, article, system, use, or method, indicates that additional elements and / or method steps may be present, but that these additions do not materially affect the manner in which the recited composition, device, article, system, method, or use functions. A composition, device, article, system, use, or method described herein as comprising particular elements and / or steps may, in certain embodiments, essentially comprise those elements and / or steps, and may comprise those elements and / or steps in other embodiments, regardless of whether those embodiments are specifically referred to.

[0088] As used herein, the term "about" refers to about a + / - 10% variation from a given value. It should be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.

[0089] The recitation of ranges herein is intended to convey both the range and the individual values ​​falling within the range, in the same place as the numbers used to denote the range, unless otherwise indicated herein.

[0090] The use of any example or exemplary language, such as "such as," "exemplary embodiment," "illustrative embodiment," and "for example," is intended to illustrate or illustrate aspects, embodiments, variations, elements, or features related to the invention and is not intended to limit the scope of the invention.

[0091] As used herein, the terms "connect" and "connected" refer to any direct or indirect physical association between elements or features of the present disclosure. These terms may be understood to indicate elements or features that are partially or completely contained within, attached to, coupled, positioned, joined together, in communication with, operably associated with, etc., even if there are other elements or features between the elements or features described as connected.

[0092] As used herein, the term "OLED" refers to an organic light-emitting diode, an optoelectronic device that emits light under the application of an external voltage. OLEDs have a light-emitting electroluminescent layer, or organic material or species, that emits light in response to an electric current. OLEDs can be divided into two major classes: those made with small organic molecules and those made with organic polymers. Without being bound by theory, when an electric current is applied, the anode injects holes and the cathode injects electrons into the organic layer. The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and a hole localize on the same molecule, an exciton, a localized electron-hole pair with an excited energy state, is formed. Light is emitted when the exciton relaxes via a light-emitting mechanism. Types of OLEDs include, but are not limited to, active-matrix OLEDs (AMOLEDs) and passive-matrix OLEDs (PMOLEDs). AMOLEDs have a total layer of a cathode, organic molecules, and an anode. The anode layer has a thin-film transistor (TFT) surface parallel to it to form a matrix. This helps switch each pixel to its on or off state as desired, thus forming an image. Thus, pixels can be turned off whenever they are not needed or when a black image is displayed, reducing the energy required to illuminate the display. This is the lowest-power type of OLED and has a faster refresh rate suitable for video. PMOLEDs have a similar composition to AMOLEDs, but the cathode lines are arranged perpendicular to the anode lines. Electrical control is achieved through the anode and cathode lines, activating pixels at their intersections to generate light. The display background of PMOLEDs is always black, and when a pixel is turned on, it displays a predetermined color. PMOLED pixels are fixed to a single color and are not suitable for dynamic images or displays. OLEDs can be top-emitting or bottom-emitting. Top-emitting OLEDs have a substrate that can be either opaque or reflective. OLEDs are bottom-emitting when the emitted light passes through a transparent or semi-transparent bottom electrode and substrate.Top-emitting OLEDs are generally more suitable for active matrix applications because they can be more easily integrated with non-transparent transistor backplanes.

[0093] As used herein, the term "DBR" refers to a distributed Bragg reflector, which is an optical mirror composed of different dielectric layers with different refractive indices in an alternating order.

[0094] As used herein, the term "optical path length," denoted by Λ, refers to the distance between two points (P1, P2) that describes the refractive index (n) of the material through which light passes. In an exemplary OLED device, the medium through which light passes may include one or more semitransparent or transparent intermediate electrodes and other layers, as well as layers comprising a white OLED stack. The optical path length is defined as a function of:

number

[0095] As used herein, the term "light field" refers to a function that describes the amount of light flowing in all directions through a point in space. A light field can describe radiance as a function of the position and direction of light in free space, preferably without occlusions. Light fields can be synthetically generated, for example, by various rendering processes, or captured from a light field camera or an array of light field cameras.

[0096] As used herein, the term "light field display" refers to a device that reconstructs a light field. In one example, a light field can be reconstructed from a finite number of light field radiance samples input to a light field display device. The radiance samples generally represent red, green, and blue (RGB) color components. For reconstruction in a light field display, the light field can also be understood as a mapping from a four-dimensional space to a single RGB color, where the four dimensions include the vertical and horizontal dimensions of the display and two dimensions that describe the directional component of the light field. In one example, the light field can be defined as a function: LF:(x,y,u,v)→(r,g,b) Given x f ,y f In the case of LF(x f ,y f ,u,v) represents a two-dimensional (2D) image called an "element image", and an element image is a given x f ,y f This is a directional image of the light field from a given position. The concatenation of multiple elemental images is called an "integral image." The integral image can be understood as the entire light field required for a light field display.

[0097] As used herein, the term "aperture ratio" in describing an optical display refers to the ratio of the light-emitting area compared to the total pixel area, defined as a function.

number

[0098] As used herein, the term "pixel" refers to the light source and light-emitting mechanism used to create the display.

[0099] As used herein, the term "subpixel" refers to a structure consisting of a light-emitting device housed within an optical microcavity.

[0100] As used herein, the term "electrode" refers to a conductor through which electricity enters or leaves an object, substance, or area.

[0101] As used herein, the term "cathode" refers to a negatively charged electrode through which electrons enter an electrical device.

[0102] As used herein, the term "anode" refers to a positively charged electrode through which electrons exit an electrical device.

[0103] As used herein, the term "patterning" refers to the technique of transferring a pattern onto a target material.

[0104] As used herein, the term "wavelength" is a measure of the distance between two identical peaks (high points) or troughs (low points) of a wave, which is a repeating pattern of moving energy such as light or sound.

[0105] This document describes microcavity organic light-emitting diode (OLED) designs and methods for preparing micron-sized, multicolor optical microcavity OLED arrays. Light field displays require pixel densities of at least 25,000 pixels per inch (ppi), with each pixel being less than 20 μm in size. Most preferably, light field displays with high display resolution have pixel densities greater than 5,000 ppi. Achieving high aperture ratios at these resolutions can be achieved by maximizing the emissive area of ​​each subpixel and minimizing subpixel spacing. This disclosure provides optical microcavity pixel devices comprising organic light-emitting diodes (OLEDs) and photolithographic patterning methods for achieving micron-sized pixels that, when patterned into arrays, yield aperture ratios greater than 70%, suitable for light field displays with resolutions greater than 1,000 ppi. This can be achieved by patterning transparent or semitransparent optical filler layers and intermediate electrodes to laterally overlap other intermediate electrodes in the OLED array, reducing lateral spacing and increasing the aperture ratio of the resulting OLED array. This lateral overlap design allows designers to optimize the optical properties of each OLED device and the aperture ratio of the OLED array as a whole. While the industry definition of high aperture ratio for displays with micron-sized pixels is 70%, this design allows the display to achieve an aperture ratio of nearly or about 100%, creating a high-quality display suitable for light field displays and other applications. Also disclosed are methods for designing and fabricating arrays of OLED devices that emit light including, but not limited to, yellow, red, green, or blue light.

[0106] Various features of the present invention will become apparent from the following detailed description, taken in conjunction with the illustrative drawings. The design parameters, design methods, configurations, and uses of the optical microcavity OLED design processes and structures disclosed herein are described with reference to various examples that represent embodiments that are not intended to limit the scope of the invention described and claimed herein. Those skilled in the art to which the present invention pertains will appreciate that there may be other variations, examples, and embodiments of the invention not disclosed herein that can be implemented in accordance with the teachings of the present disclosure without departing from the scope of the present disclosure.

[0107] Each OLED in the device comprises an electrode configured to interface with the substrate, an optical microcavity including a distributed Bragg reflector (DBR), and a cathode. The optical microcavity is operatively associated with or connected to one or more reflective surfaces to substantially collimate, manipulate, or condition light. At least one of the reflective surfaces is a light-propagating reflective surface connected to the optical microcavity to propagate light from the optical microcavity. The present disclosure provides individually addressable red, green, and blue (RGB) subpixels. Presently described subpixel sizes range from nanoscale to several microns. The DBR, as described herein, is composed of alternating stacks of dielectric materials of specific thicknesses, ensuring an optical path length of one-quarter of the design wavelength, making it suitable for use in OLEDs of any color. The highest reflectivity of the DBR is achieved when the layer thicknesses are selected such that the optical path length of each layer is one-quarter of the resonant wavelength. Each layer has a λ Bragg With an optical path length of λ / 4, all reflections add in phase and the transmittance decreases exponentially as a function of mirror thickness. At wavelengths longer or shorter than the stopband, the reflections begin to go out of phase, so total reflection decreases. This results in a broadband region of high reflectivity centered at the Bragg wavelength, called the stopband, with oscillating side lobes on either side. DBRs generally consist of a pair of two different dielectric layers with different refractive indices, but with an optical path length of λ for each layer. Bragg It can also be made of multiple dielectric materials or other transparent materials with a contrast of n, as long as n is / 4. A multi-layer mirror comprises alternating layers of substantially non-absorbing material of appropriately selected thicknesses. Typically, each layer has a thickness

number

[0108] FIG. 1A shows a cross-sectional view of one embodiment of a two-color optical microcavity OLED array described herein, having two OLED devices of a first color and one OLED device of a second color. The illustrated OLED array includes a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate, which is a device that forms the base structure of one embodiment of an OLED and provides electrical control for switching each pixel or subpixel to its on or off state as needed. The TFT includes several layers, including a metal gate electrode, a gate insulator, a semiconductor layer, and source / drain electrodes deposited on the substrate. The TFT substrate also preferably has a planarization layer onto which the OLED materials are deposited. The DBR 12 includes a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. The number of high-index dielectric layers 76 and low-index dielectric layers 78 can be any integer. In the illustrated embodiment, the DBR 12 can serve as the first reflective surface of the optical microcavity of each OLED device in the OLED array.

[0109] Before each electrode in the series of electrodes for the array of first-color OLED devices, referred to herein as first-color electrodes 14A and 14B, is deposited on the DBR 12, each via for each first-color OLED, referred to herein as first-color vias 16A and 16B, is dry-etched through the DBR 12. This provides electrical connection from the substrate 10 to the first-color electrodes 14A and 14B. The first-color vias 16A and 16B may be etched using an etching technique such as reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, or transmission coupled plasma etching. In this embodiment, a preferred dry etching method, such as reactive ion etching, is used. After the first-color vias 16A and 16B are etched through the DBR 12, the first-color electrodes 14A and 14B are deposited on the DBR 12 using a shadow mask. The first optical filler layer 18 is patterned directly on the DBR 12 between the first color electrodes 14A, 14B using photolithography for each second-color OLED device in the OLED array. This patterning can be achieved, for example, by chemically engraving the transferred pattern into the transferred material or by depositing new material onto the transferred material using a series of post-processing steps. A second optical filler layer 20 is then patterned for each second-color OLED device in the OLED array on the first optical filler layer 18, overlying the first optical filler layer 18, using a shadow mask or photolithography. The second optical filler layer 20 may overlap the first color electrodes 14A, 14B to form overlap regions 80A, 80B. The overlap regions 80A, 80B provide tolerances that mitigate alignment errors during manufacturing, thereby increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. The optical filler layer is designed to be transparent to visible light and electrically insulating, acting as an electrical insulating layer to prevent crosstalk between the first color electrodes 14A, 14B and the second color electrodes 22 in the overlap regions 80A, 80B.

[0110] Before the second-color electrodes 22 are deposited on the second optical filler layer 20, second-color vias 24 for each of the second-color electrodes 22 are dry-etched using reactive ion etching through the second optical filler layer 20, the first optical filler layer 18, and the DBR 12. The second-color vias 24 provide electrical connections from the substrate 10 to the second-color electrodes 22. The second-color electrodes 22 are then patterned on the second optical filler layer 20 using a shadow mask, preferably with the same width as the second optical filler layer 20. For a two-color OLED array, a layer of a white OLED stack 26 is then deposited over the entire OLED array. For a three-color OLED array, a third optical filler layer, a fourth optical filler layer, a third-color via, and a third-color electrode are deposited for the third color, followed by the deposition of the white OLED stack 26. The uniformly deposited OLED stack emits white light, and for each color optical microcavity, the optical path length is adjusted to achieve a specific color. Cathode 28 is then deposited onto the white OLED stack 26, for example, using thermal evaporation. In this embodiment, cathode 28 is a reflective material deposited at a thickness that results in greater than 0% transmittance and is used to form the optical microcavity of each OLED device.

[0111] In this embodiment, the substrate 10 comprises a non-conductive component that forms the base of the OLED device and a conductive component that provides power to each electrode. One example is a thin-film transistor (TFT) substrate composed of one or more semiconductor materials, a gate insulator, and a substrate. Semiconductor materials can include organic materials such as hydrogenated amorphous silicon, polycrystalline silicon, amorphous oxide semiconductors, cadmium selenide, zinc oxide, pentacene, poly(3-hexylthiophene), poly(3-alkylthiophene), and poly(3-octylthiophene), or transparent electrodes such as indium zinc oxide (IZO) or indium tin oxide (ITO). Indium tin oxide (ITO) is typically found as an oxygen-saturated composition with a formulation of 74% In, 18% O, and 8% Sn by weight. ITO is also commonly used as an anode material in OLED structures due to its suitable electrical conductivity, nearly transparent and colorless optical properties, and ability to be deposited by established methods. ITO can also be used to construct the anode layer of an OLED device according to the present disclosure. The gate insulator can be a metal passivation material with a transparent insulator such as SiO2 and Si3N4, or an organic material such as polymethyl methacrylate. The substrate can be a non-conductive material such as glass. The DBR 12 comprises alternating high-index and low-index dielectric layers 76 and 78, which can be composed of TiO2 and SiO2. The first-color electrodes 14A, 14B and the second-color electrode 22 can be semi-transparent or transparent conductive materials such as ITO, conductive polymers such as doped polyaniline, or thin layers (between 5 and 35 nm, preferably less than 10 nm) of metals or alloys, or carbon-based materials such as graphene. Transparent conductive materials such as ITO are preferred due to their high transmittance values ​​(80-85%) and low reflectance and absorbance.

[0112] The first and second optical filler layers 18 and 20 may be transparent polymers, such as polyimide, or inorganic transparent dielectrics with various refractive index values, such as Al2O3, SiO2, or Si3N4. The first and second optical filler layers 18 and 20 may be composed of the same or different materials. The optical filler layers 18 and 20 may be deposited by, for example, sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows designers to precisely adjust the layer thickness during deposition. The thicknesses of the optical filler layers and the materials comprising them are designed to adjust the optical path length of each specific color. A preferred material for the optical filler layers has a refractive index similar to that of the bottom electrode. For example, ITO may be used for the second color electrode 22, and Al2O3 may be used for both the first and second optical filler layers 18 and 20. The white OLED stack 26 includes thin film layers of organic materials, typically including one or more of an organic hole-injection layer (HIL), an organic hole-transport layer (HTL), an emissive layer (EML), an organic electron-transport layer (ETL), and an organic electron-injection layer. The sequence of layers in the white OLED stack is designed to emit white light. The individual colors of each OLED device are achieved by adjusting the optical path length of each optical microcavity. Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin-casting, or inkjet printing. In this embodiment, thermal evaporation is a preferred method for depositing the white OLED stack 26. The cathode 28 can be a reflective metal with a reflectivity greater than 90%, such as aluminum, cadmium, or silver. This embodiment illustrates a conventional OLED configuration, in which the first color electrodes 14A, 14B and the second color electrode 22 below the white OLED stack 26 are anodes, and the top electrode above the white OLED stack 26 is the cathode 28. The microcavity OLEDs described herein have substantially reflective top and bottom surfaces with substantially transparent intermediate layers that collectively create a resonance within the optical microcavity to produce the optical path length required for the desired color.In this configuration, where DBR 12 is the bottom reflective surface and cathode 28 is the top reflective surface, cathode 28 is slightly less reflective than DBR 12, allowing light generated within the optical microcavity to emit through the top of the OLED array. Alternatively, the OLED array may be configured as an array of inverted OLED devices, where the bottom electrode deposited below white OLED stack 26 is a fully transparent cathode, and the top electrode above the white OLED stack is a reflective anode. The OLED arrays described herein may also be configured as arrays of bottom-emitting OLED devices, where the bottom electrode, DBR 12, and substrate 10 are slightly less reflective than the top electrode, and emit light through substrate 10. The OLED arrays may also be configured to consist of any combination of inverted or non-inverted and top- or bottom-emitting OLEDs.

[0113] In an optical microcavity, the optical path length of each color is equal to the peak wavelength of the color divided by 2 and multiplied by a positive integer. therefore,

number

[0114] Each element comprising the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length for each color can be determined by the optical path length of each element comprising the optical microcavity: DBR 12, electrodes 14, 22, optical filler layers 18, 20, white OLED stack 26, and cathode 28. Because DBR 12 and cathode 28 are reflective surfaces that form the boundaries of the optical microcavity, the penetration depth of DBR 12 and cathode 28 is considered in addition to refractive index and thickness. In this embodiment, DBR 12 and cathode 28 are uniform, and the white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length for each color includes the penetration depth of DBR 12 and the penetration depth of cathode 28. These penetration depths are incorporated into the design and are constant across the entire OLED array. Although DBR 12 and cathode 28 are present, they are not used to tailor the optical path length to emit a specific color. therefore,

number

[0115] The optical path length Λ of each first color OLED device in the OLED array C1 (referred to herein as the optical path length of the first color 30A, 30B) is the optical path length of the first electrode (referred to herein as the optical path length of the first electrode (Λ)) of each first color OLED device in the OLED array. e1 ) 34A, 34B) and the white OLED stack (Λ OLED ) 32. The optical path length Λ of each second color OLED device in the OLED array C2 (Herein, the optical path length (Λ) of the second color C2 ) 36) is the optical path length (Λ) of the first optical filler layer. f1 ) 38, the optical path length of the second optical filler layer (Λ f2 ) 40, the optical path length of the second color electrode (Λ e2 ) 42, and the optical path length (Λ) of the white OLED stack OLED) 32. Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited over the OLED array, the white OLED stack (Λ OLED ) 32 is the optical path length of the first color (Λ C1 ) 30A, 30B, can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. In particular, the optical path length of the first color (Λ C1 ) should be approximately equal to the peak wavelength of the first color divided by two integer times. Because the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 The thickness of second optical filler layer 20 can also be designed to create the required optical path length for white OLED stack 32. Because white OLED stack 32 can be uniform, it is advantageous to use the optical path length of white OLED stack 26 to optimize the optical path length of first colors 30A, 30B, and the optical path length of second optical filler layer 40 to optimize the optical path length of second color 36. A uniform white OLED stack 26 can then be deposited over the entire OLED array, thereby simplifying manufacturing.

[0116] FIG. 1B shows an expanded view of the monochromatic optical microcavity OLED device depicted in FIG. 1A. The OLED device comprises a DBR 12 deposited on a substrate 10, which may be a TFT substrate. The DBR 12 comprises a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. Note that while the number of pairs of high-index dielectric layers 76 and low-index dielectric layers 78 shown in FIG. 1B is three, comprising six layers, the DBR can be composed of any integer number of layers. This configuration allows the DBR 12 to function as the first reflective surface for the optical microcavity of each OLED device in the OLED array. A first-color electrode 14 is deposited on the DBR 12 using a shadow mask. The layers comprising the white OLED stack 26 are then individually deposited across the entire OLED array. Each layer of the white OLED stack 26 can be deposited by, for example, thermal evaporation, spin-casting, or inkjet printing, preferably by thermal evaporation. In this embodiment, the white OLED stack 26 can include one or more of the following layers: an organic hole-injection layer (HIL) 84, an organic hole-transport layer (HTL) 86, an emissive layer (EML) 88, an organic electron-transport layer (ETL) 90, and an organic electron-injection layer (EIL) 92. In some configurations, the white OLED stack 26 can include a single EML 88, where emissive molecules of a particular color are combined within the EML 88 to generate white light. In alternative configurations, the white OLED stack 26 can include multiple EMLs 88, which can be referred to as tandem or stacked white OLEDs. In a tandem white OLED, white light is generated from all of the emissive EMLs 88 in the white OLED stack 26. In a tandem OLED configuration, additional charge-generation layers can be deposited to function as additional injection layers and artificial metal electrodes. The combination of organic layers within the white OLED stack 26 is designed to emit white light, and each optical microcavity adjusts the optical path lengths of the various elements to achieve a specific color. Cathode 28 is then deposited, for example using thermal evaporation, on the white OLED stack 26. In this embodiment, cathode 28 is a reflective material and is used to form an optical microcavity for each OLED device.

[0117] FIG. 1C shows an expanded view of the two-color optical microcavity OLED device shown in FIG. 1A. The OLED device includes a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate. The DBR 12 includes a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. The number of high-index dielectric layers 76 and low-index dielectric layers 78 can be any integer. This configuration allows the DBR 12 to function as the first reflective surface of the optical microcavity of each OLED device in the OLED array. A first-color electrode 14 is deposited on the DBR 12 using a shadow mask. A first optical filler layer 18 is patterned directly on the DBR 12 adjacent to the first-color electrode 14 using photolithography for each second-color OLED device in the OLED array. A second optical filler layer 20 is then patterned for each second-color OLED device in the OLED array on the first optical filler layer 18 using a shadow mask or photolithography. The second optical filler layer 20 can cover the entire first optical filler layer 18 and overlap the first-color electrode 14 to form an overlap region 80. The overlap region 80 mitigates alignment errors in manufacturing and therefore increases the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. A second-color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, and preferably has the same width as the second optical filler layer 20. While only first and second microcavities are shown here, it is understood that the OLED array comprises a plurality of first-color microcavities with first electrodes and a plurality of second-color microcavities with second electrodes. It is further understood that an OLED array also generally comprises a plurality of three different colored microcavities to provide red, green, and blue emission.

[0118] The layers comprising the white OLED stack 26 are then individually deposited across the entire OLED array. Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin-casting, or inkjet printing. In this embodiment, thermal evaporation is the preferred method. In this embodiment, the organic layers comprising the white OLED stack 26 are deposited on the first and second color electrodes 14, 22 in the following order: an organic hole-injection layer (HIL) 84, an organic hole-transport layer (HTL) 86, an emissive layer (EML) 88, an organic electron-transport layer (ETL) 90, and an organic electron-injection layer (EIL) 92. The white OLED stack 26 can further comprise one or more of each organic layer. The organic layers of the white OLED stack 26 are designed together to emit white light, and each optical microcavity adjusts the optical path length of the various elements to achieve a specific color. A cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, cathode 28 is a reflective material and is used to form an optical microcavity for each OLED device.

[0119] FIG. 2 shows an alternative embodiment of a two-color optical microcavity OLED array according to the present disclosure, including a pixel-defining layer (PDL) 44. The cross section shows two OLED devices of a first color and one OLED device of a second color. The OLED array comprises a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate, a device that forms the base structure of this embodiment. The DBR 12 comprises a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. Before the first-color electrodes 14A, 14B are deposited on the DBR 12, first-color vias 16A, 16B are dry-etched through the DBR 12 to provide electrical connection from the substrate 10 to the first-color electrodes 14A, 14B. In this embodiment, the preferred dry etching method is reactive ion etching. The first-color electrodes 14A, 14B are then patterned on the DBR 12 using a shadow mask. The first optical filler layer 18 is patterned using photolithography on the DBR 12 between the first color electrodes 14A, 14B. The second optical filler layer 20 can be deposited on the first optical filler layer 18, completely covering the first optical filler layer 18 and overlapping the first color electrodes 14A, 14B to form overlap regions 80A, 80B. The second optical filler layer can be patterned using a shadow mask or photolithography. The overlap regions 80A, 80B provide tolerances that mitigate alignment errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10.

[0120] Before the second color electrode 22 is deposited, second color vias 24 are dry etched using reactive ion etching through the optical filler layers 20, 18 and DBR 12 to provide electrical connection to the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, with a width equal to the width of the second optical filler layer 20. In this embodiment, an optional PDL 44 is patterned using a shadow mask to cover areas of the second color electrode 22 and second optical filler layer 20 that overhang the adjacent first color electrodes 14A, 14B. The PDL 44 prevents electrical shorts between the first color electrodes 14A, 14B and the second color electrode 22, reducing crosstalk across the OLED array. Crosstalk generally refers to light leaking from one pixel to another when emitted, which can disrupt image quality, causing loss of contrast, loss of depth resolution, viewer discomfort, and duplication of the displayed image. The PDL 44 can be deposited by, for example, sputtering, spin coating, thermal evaporation, chemical vapor deposition, atomic layer deposition, spin casting, etc. The optional PDL 44 can be composed of an insulating dielectric, such as an inorganic material like Al2O3, Si3N4, or SiO2, or an organic material like a photosensitive polyimide. In a three-color OLED device, the PDL layer can also connect the third color electrode to the second color electrode. The layers comprising the white OLED stack 26 are deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26 by thermal evaporation. In this embodiment, the cathode 28 is a reflective material and is therefore used to form the optical microcavity for each OLED device.

[0121] The first color (Λ C1 ) 30A, 30B has an optical path length of the first electrode (Λ e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32. The second color (Λ C2 ) 36 is the optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λf2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED ) 32. Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can adjust the optical path length of a desired color. Once the white OLED stack 26 is deposited across the OLED array, the white OLED stack (Λ OLED ) 32 is the optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36 may be designed across the thickness of the second optical filler layer 20 to create the required optical path length.

[0122] Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B and the optical path length of the second optical filler layer 40 to optimize the optical path length of the second color 36 is advantageous because it allows for a uniform white OLED stack 26. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0123] FIG. 3A shows another embodiment of a two-color optical microcavity OLED array with a second DBR 12B deposited on top of the cathode 28. The cross section shows two OLED devices of a first color and one OLED device of a second color. The OLED array includes a first DBR 12A deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate, forming the base structure of the device. The first DBR 12A has alternating high-index dielectric layers 76 and low-index dielectric layers 78. Before the first-color electrodes 14A, 14B are deposited on the first DBR 12A, first-color vias 16A, 16B are dry etched through the first DBR 12A to provide electrical connection from the substrate 10 to the first-color electrodes 14A, 14B. In a preferred embodiment, the vias are formed using reactive ion etching. Next, first-color electrodes 14A and 14B are patterned on the first DBR 12A using a shadow mask. Then, a first optical filler layer 18 is patterned on the first DBR 12A between the first-color electrodes 14A and 14B using photolithography. A second optical filler layer 20 is then deposited to completely cover the first optical filler layer 18 and preferably overlap the first-color electrodes 14A and 14B, forming overlap regions 80A and 80B. The second optical filler layer 20 can be patterned using a shadow mask or photolithography. The overlap regions 80A and 80B provide a tolerance that mitigates alignment errors during manufacturing, thereby increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10.

[0124] Before the second color electrode 22 is deposited, a second color via 24 is dry etched using reactive ion etching through the optical filler layers 20, 18 and the first DBR 12A to provide electrical connection to the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, with a width approximately equal to that of the second optical filler layer 20. The layers comprising the white OLED stack 26 are then deposited over the entire OLED array. A cathode 28 is then deposited on the white OLED stack 26 by thermal evaporation. In this embodiment, an additional DBR 12B is deposited on top of the cathode 28. The second DBR 12B has a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. The cathode 28 is composed of a semi-transparent or transparent material, and the DBR 12B is used to form the optical microcavity for each OLED device.

[0125] Each element comprising the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length for each color can be determined by the optical path lengths of each element comprising the optical microcavity: first DBR 12A, first electrodes 14A and 14B, second electrode 22, optical filler layers 18 and 20, white OLED stack 26, cathode 28, and second DBR 12B. Because first DBR 12A and second DBR 12B are reflective surfaces that form the boundaries of the optical microcavity, the penetration depth of DBRs 12A and 12B is considered in addition to the refractive index and thickness. In this embodiment, DBRs 12A and 12B and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length for each color includes the penetration depth of first DBR 12A, the penetration depth of second DBR 12B, and the optical path length of cathode 28. These penetration depths and corresponding optical path lengths are constant across the OLED array, although this is a design consideration. The first DBR 12A, the second DBR 12B, and the cathode 28 are not used to tailor the optical path length to emit a particular color. therefore,

number

[0126] The first color (Λ C1 ) 30A, 30B has an optical path length of the first electrode (Λ e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32. The second color (Λ C2 ) 36 is the optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λ f2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED ) 32. Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can adjust the optical path length of a desired color. Once the white OLED stack 26 is deposited over the OLED array, the white OLED stack (Λ OLED ) 32 is the optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36. Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B and the optical path length of the second optical filler layer 40 to optimize the optical path length of the second color 36 is advantageous because it allows the white OLED stack 26 to be uniform across the OLED optical microcavity array. A uniform white OLED stack 26 can also be deposited across the entire OLED array, thereby simplifying manufacturing.

[0127] FIG. 3B shows an expanded view of the two-color optical microcavity OLED device shown in FIG. 3A. The OLED device includes a first DBR 12A deposited on a substrate 10, preferably a TFT substrate. The first DBR 12A is composed of alternating high-index dielectric layers 76 and low-index dielectric layers 78. The number of high-index and low-index dielectric layers 76 and 78 can be any integer number of layers, with three pairs shown in this configuration providing six layers. In this embodiment, the first DBR 12A serves as the first reflective surface for the optical microcavity of each OLED device in the OLED array. A first-color electrode 14 is deposited on the first DBR 12A using a shadow mask. A first optical filler layer 18 is patterned using photolithography adjacent to the first-color electrode 14 and directly on the first DBR 12A for each second-color OLED device in the OLED array. The second optical filler layer 20 can then be patterned for each second-color OLED device in the OLED array on the first optical filler layer 18 using a shadow mask or photolithography to cover the entire first optical filler layer 18 and overlap the first-color electrode 14 to form an overlap region 80. The overlap region 80 mitigates alignment errors in manufacturing and therefore increases the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. The second-color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, and preferably the width of the second-color electrode 22 is the same as the width of the second optical filler layer 20.

[0128] The layers comprising the white OLED stack 26 are then individually deposited across the entire OLED array. Each layer of the white OLED stack 26 can be deposited, for example, by thermal evaporation, spin-casting, or inkjet printing. In this embodiment, thermal evaporation is the preferred method. The organic layers comprising the white OLED stack 26 are then deposited on the first and second color electrodes 14, 22 in the following order: organic hole-injection layer (HIL) 84, organic hole-transport layer (HTL) 86, light-emitting layer (EML) 88, organic electron-transport layer (ETL) 90, and organic electron-injection layer (EIL) 92. The white OLED stack 26 can comprise one or more of each organic layer. The organic layers are designed to emit white light, and each optical microcavity adjusts the optical path length of the various elements to achieve a specific color. A cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, cathode 28 is composed of a semi-transparent or transparent material, and second DBR 12B is deposited on cathode 28. Second DBR 12B comprises a series of alternating high refractive index dielectric layers 76 and low refractive index dielectric layers 78. The number of high refractive index dielectric layers 76 and low refractive index dielectric layers 78 in second DBR 12B can also be any integer number. This configuration allows second DBR 12B to function as the top reflective surface of the optical microcavity of each OLED device in the OLED array.

[0129] FIG. 4 shows one embodiment of a cross-section of a three-color optical microcavity OLED array according to the present disclosure. The OLED array comprises a DBR 12 deposited on a substrate 10. The cross-section shows two OLED devices of a first color and a single OLED device each of a second and third color. In this embodiment, the substrate 10 is a TFT substrate, a device that forms the base structure of the OLED array. The DBR 12 comprises a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78, and the number of high-index dielectric layers 76 and low-index dielectric layers 78 can be any integer number. In this configuration, the DBR 12 is the first reflective surface for the optical microcavity of each OLED device in the OLED array.

[0130] Before the first-color electrodes 14A, 14B for the array of first-color OLED devices are deposited on the DBR 12, first-color vias 16A, 16B are dry-etched through the DBR 12 to provide electrical connection from the substrate 10 to the first-color electrodes 14A, 14B. The vias can be etched by, for example, reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, and transmission coupled plasma etching. One preferred dry etching method for constructing the vias is reactive ion etching. After the first-color vias 16A, 16B are etched through the DBR 12, the first-color electrodes 14A, 14B are patterned on the DBR 12 using a shadow mask. Then, for each second-color OLED device in the OLED array, a first optical filler layer 18 is patterned using photolithography directly on the DBR 12 between the first-color electrodes 14A, 14B. A second optical filler layer 20 may then be deposited on and partially cover the first optical filler layer 18 and overlap the first color electrode 14A to form overlap region 80A. The second optical filler layer 20 may be patterned using a shadow mask or photolithography. The overlap region 80A provides tolerance to reduce registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10.

[0131] Before the second color electrodes 22 are deposited on the second optical filler layer 20, second color vias 24 are dry etched using reactive ion etching through the second optical filler layer 20, the first optical filler layer 18, and the DBR 12. The second color vias 24 provide electrical connections from the substrate 10 to the second color electrodes 22. The second color electrodes 22 are then patterned on the second optical filler layer 20 using a shadow mask, preferably with a width equal to that of the second optical filler layer 20. The third optical filler layer 58 is then patterned using photolithography for each third color OLED device in the OLED array on the first optical filler layer 18 adjacent to the second optical filler layer 20 to overlap the first color electrodes 14B and form overlap regions 80C. A fourth optical filler layer 60 may be deposited for each third color OLED device in the OLED array on the third optical filler layer 58 and overlap with the second color electrode 22 to form overlap regions 80D. The fourth optical filler layer 60 may be patterned using a shadow mask or photolithography. The overlap regions 80C, 80D may mitigate registration errors in manufacturing and increase the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10.

[0132] Before the third color electrode 62 is deposited on the fourth optical filler layer 60, a third color via 64 is dry etched, preferably using reactive ion etching, through the fourth optical filler layer 60, the third optical filler layer 58, the first optical filler layer 18, and the DBR 12. The third color via 64 provides an electrical connection from the substrate 10 to the third color electrode 62. The third color electrode 62 is then patterned on the fourth optical filler layer 60 using a shadow mask, preferably with a width equal to the width of the fourth optical filler layer 60. Next, layers comprising the white OLED stack 26 are deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, the cathode 28 is a reflective material and is therefore used to form the optical microcavity for each OLED device.

[0133] In this embodiment, the substrate 10 may be a thin-film transistor (TFT) substrate composed of a semiconductor material, a gate insulator, and a substrate. The semiconductor material may include, for example, hydrogenated amorphous silicon, polycrystalline silicon, amorphous oxide semiconductor, cadmium selenide, zinc oxide; organic materials such as pentacene, poly(3-hexylthiophene), poly(3-alkylthiophene), and poly(3-octylthiophene); or a transparent electrode such as ITO. The gate insulator may be a transparent insulator such as SiO2 or Si3N4, or a metal passivated with an organic material such as polymethylmethacrylate. The substrate may be a non-conductive material such as glass. The DBR 12 includes alternating high-index dielectric layers 76 and low-index dielectric material layers 78. The electrodes 14A, 14B, 22, and 62 can be semitransparent or transparent conductive materials such as ITO, conductive polymers such as doped polyaniline, or thin layers of metals or alloys (between 5 and 35 nm, preferably less than 10 nm), and carbon-based materials such as graphene. Transparent conductive materials such as ITO are preferred for the present disclosure due to their high transmittance (80-85%) and low reflectance and absorbance. The optical filler layers 18, 20, 58, and 60 can comprise transparent polymers such as polyimide, or inorganic transparent dielectrics with various refractive index values, such as Al2O3, SiO2, or Si3N4. The optical filler layers 18, 20, 58, and 60 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. Preferred materials for the optical filler layers have a refractive index similar to that of the bottom electrodes. For example, ITO is a preferred material for the second color electrode 22 and the third color electrode 62, in which case Al2O3 is a preferred material for the optical filler layers. The preferred deposition method is sputtering, which allows the designer to precisely control the layer thicknesses during deposition. The white OLED stack 26 includes thin film layers of organic materials, typically including one or more of an organic hole-injection layer (HIL), an organic hole-transport layer (HTL), an emissive layer (EML), an organic electron-transport layer (ETL), and an organic electron-injection layer. The series of OLED layers is designed to emit white light.Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, and inkjet printing. In this embodiment, thermal evaporation is the preferred method. The individual color of each OLED device is achieved by modulating the optical path length of each optical microcavity. The cathode 28 can be a reflective metal with a reflectivity greater than 90%, such as aluminum, cadmium, or silver. This embodiment shows a conventional OLED configuration in which the bottom electrode 14A, 14B, 22, 62 below the white OLED stack 26 is the anode, and the electrode above the white OLED stack 26 is the cathode 28. The present disclosure can also be configured as an array of inverted OLED devices, in which the bottom electrode deposited before the white OLED stack 26 is the cathode 28, and the top electrode above the white OLED stack 26 is the anode. The present disclosure can also be configured as an array of bottom-emitting OLED devices, in which the bottom electrode, DBR 12, and substrate 10 are semitransparent or transparent, and light is emitted through the substrate 10. The disclosed embodiments can be configured to be any combination of inverted or non-inverted and top or bottom emitting.

[0134] Each element comprising the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length for each color can be determined by the optical path length of each element comprising the optical microcavity: DBR 12, electrodes 14, 22, 62, optical filler layers 18, 20, 58, 60, white OLED stack 26, and cathode 28. Because DBR 12 and cathode 28 are reflective surfaces that form the boundaries of the optical microcavity, the penetration depths of DBR 12 and cathode 28 are considered in addition to refractive index and thickness. In this embodiment, DBR 12 and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length for each color includes the penetration depth of DBR 12 and the penetration depth of cathode 28. These penetration depths are incorporated into design considerations but are constant across the entire OLED array. The DBR 12 and cathode 28 shown are not used to adjust the optical path length to emit a particular color. therefore,

number

[0135] The optical path length Λ of each first color OLED device in the OLED array C1 (referred to herein as the optical path length of the first color 30A, 30B) is the optical path length of the first electrode (referred to herein as the optical path length of the first electrode (Λ)) of each first color OLED device in the OLED array. e1 ) 34A, 34B) and the white OLED stack (Λ OLED ) 32. The optical path length Λ of each second color OLED device in the OLED array C2 (Herein, the optical path length (Λ) of the second color C2 ) 36) is the optical path length (Λ) of the first optical filler layer. f1 ) 38, the optical path length of the second optical filler layer (Λ f2 ) 40, the optical path length of the second color electrode (Λ e2 ) 42, and the optical path length (Λ) of the white OLED stack OLED )32. The optical path length Λ of each third color OLED device in the OLED array is determined by the sum of C3 (Herein, the optical path length (Λ) of the third color is C3 ) 66) is the first optical filler layer (Λ f1 ) 38 optical path length, the third optical filler layer (Λ f3 ) 68 optical path length, the fourth optical filler layer (Λ f4 ) 70 optical path length, the third color electrode (Λ e3 ) 72 optical path length, and the white OLED stack (Λ OLED ) is determined by the sum of the 32 optical path lengths.

[0136] Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited over the OLED array, the white OLED stack (Λ OLED ) 32 is the optical path length of the first color (Λ C1) 30A, 30B, can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. In particular, C1 The optical path length of the second optical filler layer (Λ) 30A, 30B should be approximately equal to or equal to the peak wavelength of the first color divided by two integer times. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ) f2 ) 40 is the optical path length of the second color (Λ C2 The thickness of the second optical filler layer 20 can also be designed to adjust the optical path length required for the fourth optical filler layer (Λ f4 ) 70 is the optical path length of the third color (Λ) 70, taking into account the thickness of the fourth optical filler layer 62. C3 ) 66. Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B and the optical path lengths of the optical filler layers 40, 70 to optimize the optical path length of the second color 36 and the optical path length of the third color 66 is advantageous because it allows the white OLED stack 26 to be uniform. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0137] FIG. 5 shows another embodiment of a three-color optical microcavity OLED array according to the present disclosure, including a pixel-defining layer (PDL) 44. The cross section shows two OLED devices of a first color and a single OLED device each of a second and third color. The OLED array includes a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate, forming the base structure of this embodiment. The DBR 12 includes a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. Before the first-color electrodes 14A, 14B are deposited, first-color vias 16A, 16B are dry-etched through the DBR 12 for each first-color electrode 14A, 14B to provide electrical connection to the substrate 10. In this embodiment, the preferred dry etching method is reactive ion etching. The first-color electrodes 14A, 14B are patterned on the DBR 12 using a shadow mask. The first optical filler layer 18 is patterned using photolithography on the DBR 12 between the first color electrodes 14A, 14B. The second optical filler layer 20 is deposited on the first optical filler layer 18, partially covering it and overlapping the first color electrode 14A to form an overlap region 80A. The second optical filler layer 20 can be patterned using a shadow mask or photolithography. The overlap region 80A provides tolerance to reduce registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. Second color vias 24 are then dry etched using reactive ion etching through the optical filler layers 18, 20 and the DBR 12 to provide electrical connection of the second color electrode 22 to the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, and the width of the second color electrode 22 is equal to the width of the second optical filler layer 20. The third optical filler layer 58 can be patterned on the first optical filler layer 18 adjacent to the second optical filler layer 20 using photolithography and overlap with the first color electrode 14B to form an overlap region 80C.A fourth optical filler layer 60 may be deposited on the third optical filler layer 58 and overlap the second color electrode 22 to form an overlap region 80D. The fourth optical filler layer 60 may be patterned using a shadow mask or photolithography. The overlap regions 80C, 80D may mitigate alignment errors in manufacturing and thus increase the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. A third color via 64 is then dry etched using reactive ion etching through the optical filler layers 58, 60 and the DBR 12 to provide electrical connection to the substrate 10. A third color electrode 62 is patterned on the fourth optical filler layer 60 using a shadow mask, with the width of the third color electrode 62 equal to the width of the fourth optical filler layer 60. In this embodiment, an optional PDL 44 is patterned using a shadow mask to cover the areas of the second and third color electrodes 22, 62 and optical filler layers 20, 60, 58 that overhang their respective adjacent first color electrodes 14A, 14B and second color electrodes 22. The PDL 44 is then deposited between the first color electrode 14A and the second color electrode 22, the second color electrode 22 and the third color electrode 62, and the third color electrode 62 and the first color electrode 14B. The PDL 44 can reduce crosstalk across the OLED array and prevent electrical shorts. Next, the layers comprising the white OLED stack 26 are deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26, for example, using thermal evaporation. In this embodiment, the cathode 28 is a reflective material and forms part of the optical microcavity of each OLED device.

[0138] Each element comprising the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length for each color can be determined by the optical path length of each element comprising the optical microcavity: DBR 12, electrodes 14, 22, 62, optical filler layers 18, 20, 58, 60, white OLED stack 26, and cathode 28. Because DBR 12 and cathode 28 are reflective surfaces that form the boundaries of the optical microcavity, the penetration depths of DBR 12 and cathode 28 are considered in addition to refractive index and thickness. In this embodiment, DBR 12 and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length for each color includes the penetration depth of DBR 12 and the penetration depth of cathode 28. These penetration depths are incorporated into design considerations but are constant across the entire OLED array. The DBR 12 and cathode 28 are not used to adjust the optical path length to emit a particular color. therefore,

number

[0139] The first color (Λ C1 ) 30A, 30B has an optical path length of the first electrode (Λ e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32 and the optical path length of the second color (Λ C2 ) 36 is the optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λ f2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED )32. The third color (Λ C3 ) 66 has an optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, the third optical filler layer (Λ f3 ) 68 optical path length, the fourth optical filler layer (Λ f4 ) 70 optical path length, the third color electrode (Λ e3) 72 optical path length, and the white OLED stack (Λ OLED ) is determined by the sum of the 32 optical path lengths.

[0140] Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited across the OLED array, the white OLED stack (Λ OLED ) 32 is the optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36. Similarly, the thickness of the fourth optical filler layer (Λ f4 ) 70 is designed across the thickness of the fourth optical filler layer 60 to provide a third color (Λ C3 ) 66 can be adjusted to the required optical path length.

[0141] Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B and the optical path length of the optical filler layers 40, 70 to optimize the optical path length of the second and third colors 36, 66 is advantageous because it allows for a uniform white OLED stack 26. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0142] FIG. 6 shows another embodiment of a three-color optical microcavity OLED array according to the present disclosure, including a second DBR 12B deposited on the cathode 28. The cross section shows two OLED devices of a first color and a single OLED device each for a second and third color. The OLED array includes a first DBR 12A deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate, forming the base structure of the embodiment. The first DBR 12A includes a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. First-color vias 16A, 16B are dry-etched through the first DBR 12A for each first-color electrode 14A, 14B, providing electrical connection to the substrate 10. A shadow mask is then used to pattern the first-color electrodes 14A, 14B on the first DBR 12A. Photolithography is then used to pattern a first optical filler layer 18 on the first DBR 12A between the first color electrodes 14A, 14B. A second optical filler layer 20 may then be deposited on the first optical filler layer 18, partially covering it and overlapping the first color electrode 14A to form an overlap region 80A. A shadow mask or photolithography may then be used to pattern the second optical filler layer 20. The overlap region 80A provides a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. Second color vias 24 are then etched through the first and second optical filler layers 18, 20, and the first DBR 12A to provide electrical connection of the second color electrode 22 to the substrate 10. The second color electrode 22 is then patterned using a shadow mask on the second optical filler layer 20, with the width of the second color electrode 22 equal to the width of the second optical filler layer 20. The third optical filler layer 58 can then be patterned using photolithography on the first optical filler layer 18 adjacent to the second optical filler layer 20, overlapping the first color electrode 14B to form an overlap region 80C.A fourth optical filler layer 60 can then be deposited on the third optical filler layer 58 and overlap the second color electrode 22 to form an overlap region 80D. The fourth optical filler layer 60 can be patterned using a shadow mask or photolithography. The overlap regions 80C, 80D can mitigate alignment errors in manufacturing and thus increase the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. A third color via 64 is then dry etched through the optical filler layers 58, 60 and the first DBR 12A to provide electrical connection to the substrate 10. A third color electrode 62 is then patterned on the fourth optical filler layer 60 using a shadow mask, with the width of the third color electrode 62 equal to the width of the fourth optical filler layer 60. Layers comprising the white OLED stack 26 are deposited over the entire OLED array. Cathode 28 is then deposited on white OLED stack 26 using, for example, thermal evaporation. In this embodiment, second DBR 12B is deposited on cathode 28. Second DBR 12B comprises a series of alternating high refractive index dielectric layers 76 and low refractive index dielectric layers 78. Cathode 28 is composed of a semi-transparent or transparent material, and second DBR 12B is used to form the optical microcavity for each OLED optical microcavity device.

[0143] Each element comprising the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length for each color can be determined by the optical path lengths of each element comprising the optical microcavity: first DBR 12A, electrodes 14, 22, 62, optical filler layers 18, 20, 58, 60, white OLED stack 26, cathode 28, and second DBR 12B. Because first DBR 12A and second DBR 12B are reflective surfaces that form the boundaries of the optical microcavity, the calculation of each optical path length takes into account the penetration depth of DBRs 12A and 12B in addition to the refractive index and thickness. In this embodiment, DBRs 12A and 12B and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length for each color includes the penetration depth of first DBR 12A, the penetration depth of second DBR 12B, and the optical path length of cathode 28. These penetration depths and corresponding optical path lengths are constant across the OLED array, although this is a design consideration. The first DBR 12A, the second DBR 12B, and the cathode 28 are not used to tailor the optical path length to emit a particular color. therefore,

number

[0144] The first color (Λ C1 ) 30A, 30B has an optical path length of the first electrode (Λ e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32 and the optical path length of the second color (Λ C2 ) 36 is the optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λ f2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED )32. The third color (Λ C3 ) 66 has an optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, the third optical filler layer (Λ f3) 68 optical path length, the fourth optical filler layer (Λ f4 ) 70 optical path length, the third color electrode (Λ e3 ) 72 optical path length, and the white OLED stack (Λ OLED ) is determined by the sum of the 32 optical path lengths.

[0145] Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited across the OLED array, the white OLED stack (Λ OLED ) 32 is the optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36. Similarly, the thickness of the fourth optical filler layer (Λ f4 ) 70 is designed across the thickness of the fourth optical filler layer 60 to provide a third color (Λ C3 ) 66. Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B and the optical path length of the optical filler layers 40, 70 to optimize the optical path lengths of the second and third colors 36, 66 is advantageous because it allows the white OLED stack 26 to be uniform. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0146] 7 shows one embodiment of the optical paths from substrate 10 to first color emission 50A, 50B and second color emission 52 of a two-color optical microcavity OLED array according to the present disclosure. Each subpixel in the series of subpixels of the array of first color OLED devices, referred to herein as first color subpixels 46A, 46B, is the width of the emissive area of ​​each first color OLED device, designated as first color emission 50A, 50B, respectively. Each subpixel in the series of subpixels of the array of second color OLED devices, referred to herein as second color subpixels 48, is the width of the emissive area of ​​each second color OLED device, designated as second color emission 52. Current originating from substrate 10 flows through first color vias 16A, 16B and second color via 24 to first color electrodes 14A, 14B and second color electrode 22, respectively, through white OLED stack 26, and to cathode 28. As will be appreciated by those skilled in the art, the many layers comprising the white OLED stack 26 create emissive regions where electrons emit energy in the form of photons of light, which are emitted as first color emission 50A, 50B and second color emission 52, respectively. The regions under the first color emission 50A, 50B can be considered individual optical microcavities for the first color. The design of these optical microcavities is optimized to emit light of the first color. The regions under the second color emission 52 can be considered individual optical microcavities for the second color. The design of these optical microcavities is optimized to emit light of the second color. The optical microcavities form regions where optical resonance occurs to generate and emit light of a particular color. This light is optimized for the first and second colors through the design of the lengths of the corresponding optical microcavities, which are created by the distance between the top edge of the DBR 12 and the bottom edge of the cathode 28. The white OLED stack 26 is also designed to form the desired optical microcavities for the first color OLED device. First optical filler layer 18 and second optical filler layer 20 are transparent or semi-transparent and create the desired optical microcavity length for the second color OLED device.The patterning of the first color electrodes 14A, 14B and the second color electrode 22 is designed to minimize lateral spacing, allowing the first color subpixels 46A, 46B and second color subpixels 48 and their corresponding light-emitting areas 50A, 50B, 52, respectively, to fully utilize the light-emitting area, thereby increasing the aperture ratio of the light field display.

[0147] FIG. 8 illustrates one embodiment of the optical paths from substrate 10 to first color emission 50A, 50B, second color emission 52, and third color emission 56 of a three-color optical microcavity OLED array according to the present disclosure. Each subpixel in the series of subpixels of the array of first color OLED devices, referred to herein as first color subpixels 46A, 46B, is the width of the emissive area of ​​each first color OLED device, designated as first color emission 50A, 50B. Each subpixel in the series of subpixels of the array of second color OLED devices, referred to herein as second color subpixels 48, is the width of the emissive area of ​​each second color OLED device, designated as second color emission 52. Each subpixel in the series of subpixels of the array of third color OLED devices, referred to herein as third color subpixels 54, is the width of the emissive area of ​​each third color OLED device, designated as third color emission 56. A three-color OLED array according to the present disclosure is understood to comprise a plurality of first-color subpixels, second-color subpixels, and third-color subpixels. Current generated in substrate 10 flows through vias 16A, 16B, 24, 64 to electrodes 14A, 14B, 22, 62, and through white OLED stack 26 to cathode 28. The layers comprising white OLED stack 26 form emissive regions where electrons radiate energy in the form of photons of light, which are emitted as first-color emission 50A, 50B, second-color emission 52, and third-color emission 56. The emitted light is optimized for the first, second, and third colors through the lengths of corresponding optical microcavities created by the distance between the top of DBR 12 and the bottom of cathode 28, and white OLED stack 26 is designed to create the desired optical microcavity for the first-color OLED device. The first optical filler layer 18 and the second optical filler layer 20 are transparent or semi-transparent to create the desired optical microcavity length for the second color OLED device. The first optical filler layer 18, the third optical filler layer 58, and the fourth optical filler layer 60 are transparent or semi-transparent to create the desired optical microcavity length for the third color OLED device.The patterning of the first color electrodes 14A, 14B, second color electrode 22, and third color electrode 62 minimizes lateral spacing to allow the first color subpixels 46A, 46B, second color subpixels 48, and third color subpixels 54 and their corresponding light-emitting regions 50A, 50B, 52, 56 to fully utilize the light-emitting area, thereby increasing the aperture ratio of the light field display.

[0148] Figure 9 illustrates a top view of light emission from a three-color optical microcavity OLED array with overlapping subpixels according to the present disclosure. The overlapping patterning of the first, second, and third color electrodes minimizes lateral spacing and allows the three colors of subpixels and their corresponding light-emitting regions to overlap. This allows the OLED array to fully utilize the light-emitting area, thereby increasing the aperture ratio of the light field display. As shown, first color emission 50, second color emission 52, and third color emission 56 overlap. Figure 9 illustrates a delta triplet subpixel configuration, which is one possible configuration for a three-color OLED array as currently described.

[0149] Fabrication of optical microcavity OLED devices suitable for light field displays is inherently complex due to the pixel size required to achieve a high aperture display. Figures 10A-10N illustrate a method for fabricating a two-color OLED array according to the present disclosure.

[0150] FIG. 10A shows the first step in fabrication, depositing DBR 12 onto substrate 10. In this embodiment, substrate 10 is a TFT substrate, a device that forms the base structure of this embodiment. DBR 12, as shown in FIG. 10A, is understood to comprise alternating high-index and low-index dielectric layers. Each layer of DBR 12 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, and atomic layer deposition. The preferred deposition method for this embodiment is sputtering.

[0151] 10B shows first color vias 16A, 16B dry etched through DBR 12 to connect to substrate 10. The vias can be etched by reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, and transmission coupled plasma etching. In this embodiment, the preferred dry etching method is reactive ion etching.

[0152] Figure 10C shows first-color electrodes 14A, 14B deposited on the DBR 12. First-color vias 16A, 16B provide electrical connection of the first-color electrodes 14A, 14B to the substrate 10. Electrodes can be patterned by sputtering, thermal evaporation, and spin coating. In this embodiment, sputtering is the preferred deposition method. Shadow masks are typically microstructures or stencils used to precisely define device regions for various applications, such as the first-color electrodes 14A, 14B in this embodiment. Shadow masks are designed with specific perforations that, when placed on the substrate, allow for precise patterning of elements during deposition. Precision is particularly important when depositing micron-sized OLED devices, as alignment or deposition errors can occur. This can result in suboptimal electrical and optical characteristics of the OLED device and reduce the aperture ratio of the OLED array. A shadow mask is a tool used to pattern a substrate; for example, in this embodiment, any suitable deposition method such as sputtering, thermal evaporation, and spin coating can be used in conjunction with a shadow mask to deposit the desired pattern of first color electrodes 14A, 14B on DBR 12.

[0153] Figures 10D-10G show a series of photolithography steps for patterning the first optical filler layer. Photolithography is a widely used manufacturing technique that uses photoresist and ultraviolet (UV) light to transfer a pattern onto a substrate through a photomask. The photomask can be, for example, a thin plate with a submicrometer- or nanometer-sized pattern having opaque and transparent regions of the desired pattern, and preferably contains glass or fused silica. The photomask is used in combination with UV light to transfer the pattern from the mask to the substrate in high-resolution photolithography. Photolithography is a process that begins by cleaning the top surface with a solvent, such as acetone, methanol, and isopropanol, followed by rinsing with deionized water. It should be noted that if the desired pixel size is larger than this embodiment, a shadow mask can be used for any patterning step in this embodiment.

[0154] FIG. 10D shows a cross-sectional view of the embodiment after deposition of photoresist 74. Deposition can be achieved, for example, by spin-coating deposition. Photoresist 74 is deposited on a structure comprising substrate 10 and DBR 12 having first-color electrodes 14A and 14B thereon stacked on DBR 12, each connected to substrate 10 by vias 16A and 16B. The structure with photoresist 74 is soft-baked at a temperature below approximately 110°C to remove solvent content. A patterning step can be performed, for example, using a photomask designed with a specific pattern of nano-sized opaque and transparent portions, which can be transferred to the top layer during a photolithography process. The photomask can be composed of glass, fused silica, or other suitable material. In this embodiment, the photomask is applied with a design that includes opaque portions within the pattern of the first-color electrodes 14A and 14B.

[0155] In Figure 10E, the structure on the substrate 10 with the photomask is exposed to UV light. The UV light causes a chemical change that allows the photoresist 74 to be removed by etching. During photolithography, the photoresist 74 in the area where the first optical filler layer is desired to be applied between the first electrodes 14A, 14B is removed, exposing the DBR 12, while the photoresist over the first electrodes 14A, 14B with the vias 16A, 16B remains intact. There are two types of photoresist: positive and negative. Positive photoresist chemically changes when exposed to UV light, making it soluble to etching; only the exposed portions of the photoresist are removed by etching after UV exposure. The unexposed portions of the photoresist remain insoluble. In negative photoresist, the portions of the photoresist exposed to light become insoluble to etching. In this example, photoresist 74 is preferably a positive-tone photoresist, which has been found to be easier to control during photolithography because it can maintain size and pattern, has better etching resistance, and has excellent resolution and thermal stability. However, it is understood that negative-tone photoresists may also be used. Etching removes the photoresist layer from the embodiment through chemical etching, which may be referred to as a developer, plasma etching, reactive ion etching, and ion beam milling. The photoresist material and etching process, which may include a developer material, are specifically designed to work together to create high-quality patterns without affecting other deposited materials on the embodiment. A mask, or photomask, controls where light (i.e., UV light for photolithography) is directed onto the wafer or substrate. A photomask may comprise an opaque plate with perforations or transparent areas that allow light to shine in predetermined locations. Photomask materials may include, for example, fused silica (quartz glass) with a chromium coating pattern. The photomask may be further coated with Teflon to help prevent adsorption issues during contact photolithography.In the case of a positive photoresist, the photomask has the desired pattern that is transferred to the embodiment by a photolithography process.

[0156] FIG. 10F illustrates the deposition of a first optical filler layer 18 across the entire OLED array. The first optical filler layer 18 can be deposited on the DBR 12 and photoresist 74 protecting the first electrodes 14A, 14B and vias 16A, 16B by, for example, sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows the designer to precisely control the layer thickness during deposition. The substrate 10 and layers thereon are then exposed to a stripper, which removes the photoresist 74 and the first optical filler layer 18 deposited on the photoresist 74. The photoresist stripper interacts with, fragments, and removes the photoresist 74 while leaving the remaining layers already deposited on the substrate intact. Some examples of photoresist strippers are solvents such as acetone, NMP (1-methyl-2-pyrrolidone), dimethyl sulfoxide, alkaline media such as 2-3% concentrated potassium hydroxide (KOH) or sodium hydroxide (NaOH), hydrofluoroethers; commercial strippers such as AZ100, Techni Strip P1316, P1331, N1555, and combustion with O2 plasma.

[0157] 10G shows the substrate 10 after the remaining photoresist and the first optical filler layer 18 deposited on the photoresist have been removed. Note that this entire photolithography process can be repeated for the deposition of all subsequent optical filler layers disclosed herein. The DBR 12, first electrodes 14A, 14B, and vias 16A, 16B remain intact on the substrate 10.

[0158] Figure 10H shows a top view of the embodiment of Figure 10G after photolithography steps have been completed, showing the pattern of first color electrodes 14A, 14B and first optical filler layer 18 across the OLED array, particularly how the patterning eliminates spacing between OLED devices.

[0159] FIG. 10I shows a second optical filler layer 20 deposited on the first optical filler layer 18, covering the entire first optical filler layer 18 and partially overlapping the first-color electrodes 14A and 14B to form overlap regions 80A and 80B. The second optical filler layer 20 can be deposited by, for example, sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows designers to precisely adjust the layer thickness during deposition. The overlap regions 80A and 80B provide tolerances that mitigate alignment errors during manufacturing, thereby increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. The DBR 12, first electrodes 14A and 14B, and first-color vias 16A and 16B remain intact on the substrate 10.

[0160] 10J shows second color vias 24 dry etched using reactive ion etching through first optical filler layer 18, second optical filler layer 20, and DBR 12. First electrodes 14A, 14B and first color vias 16A, 16B remain intact on substrate 10.

[0161] 10K shows second color electrode 22 deposited by sputtering on second optical filler layer 20, with the width of second color electrode 22 approximately equal to the width of second optical filler layer 20. Second color via 24 provides electrical connection of second color electrode 22 to substrate 10. First optical filler layer 18, first color electrodes 14A, 14B, first color vias 16A, 16B, and DBR 12 remain intact on substrate 10.

[0162] 10L shows a top view of the embodiment after the second color electrode 22 has been deposited. The patterning of the first color electrodes 14A, 14B and the second color electrode 22 allows for minimal spacing between OLED devices on the OLED array. The emitted color can be any color in the visible light spectrum, including, but not limited to, red, yellow, blue, and green. A preferred combination for a two-color array is yellow and blue emission.

[0163] 10M shows a white OLED stack 26 deposited on a substrate 10 that has already deposited thereon second color electrode 22, second optical filler layer 20, first optical filler layer 18, second color via 24, first color electrodes 14A, 14B, first color vias 16A, 16B, and DBR 12. The white OLED stack 26 shown in FIG. 10M comprises a series of organic material layers, and each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, or inkjet printing.

[0164] 10N shows the final step of the fabrication process, which involves depositing a cathode 28, forming an optical microcavity for each OLED device in the OLED array. Cathode 28 can be deposited by thermal evaporation and sputtering. In this embodiment, thermal evaporation is the preferred deposition method. The plurality of first and second color microcavities formed by second color electrode 22, second optical filler layer 20, first optical filler layer 18, second color via 24, first color electrodes 14A, 14B, first color vias 16A, 16B, and DBR 12, along with white OLED stack 26, form an OLED array device on substrate 10.

[0165] 11A-11V show a step-by-step process for fabricating a three-color OLED array according to the present disclosure.

[0166] FIG. 11A shows the first step in fabrication, depositing DBR 12 onto substrate 10. In this embodiment, substrate 10 is a TFT substrate, a device that forms the base structure of this embodiment. DBR 12, as shown in FIG. 11A, is understood to comprise alternating high and low refractive index dielectric layers. Each layer of DBR 12 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, and atomic layer deposition. The preferred deposition method for this embodiment is sputtering.

[0167] 11B shows first color vias 16A, 16B dry etched through DBR 12 to connect to substrate 10. Each via can be etched by reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, and transmission coupled plasma etching. In this embodiment, the preferred dry etching method is reactive ion etching.

[0168] 11C shows first color electrodes 14A, 14B deposited on DBR 12. First color vias 16A, 16B provide electrical connection of first color electrodes 14A, 14B to substrate 10. The electrodes can be patterned by sputtering, thermal evaporation, and spin coating. In this embodiment, sputtering is the preferred deposition method.

[0169] 11D-11G show a series of photolithography steps for patterning the first optical filler layer. Photolithography is a widely used manufacturing technique, and it is understood that the steps as described in FIGS. 10D-10G may be repeated for the deposition of all optical filler layers disclosed herein.

[0170] 11D shows a cross-sectional view of the embodiment after deposition of photoresist 74. Deposition can be accomplished by spin-coating deposition. Photoresist 74 is deposited on a structure comprising substrate 10 and DBR 12 having first color electrodes 14A, 14B thereon stacked on DBR 12 connected to substrate 10 by first color vias 16A, 16B, respectively. In this embodiment, a photomask is applied with a design having opaque portions in the pattern of first color electrodes 14A, 14B.

[0171] 11E, the structure with the photomask is exposed to UV light, which chemically changes the photoresist 74 adjacent to the first color electrodes 14A, 14B, making it soluble for etching. In this embodiment, the photoresist 74 is a positive photoresist. The first color electrodes 14A, 14B, the first color vias 16A, 16B, and the layer of DBR 12 deposited on the substrate 10 remain intact.

[0172] FIG. 11F shows the deposition of a first optical filler layer 18 over the entire OLED array. The first optical filler layer 18 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. The preferred deposition method is sputtering, which allows designers to precisely control the layer thickness during deposition. The substrate is then subjected to a stripping process that removes the photoresist 74 and the first optical filler layer 18 above the photoresist 74. The stripper can be a commercially available product that breaks up and removes the photoresist 74 without damaging the first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layer deposited on the substrate 10.

[0173] 11G shows the embodiment after removing the remaining photoresist and the first optical filler layer 18 deposited on the photoresist, leaving the first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layer intact on the substrate 10.

[0174] 11H shows a top view of the embodiment after the photolithography steps are completed, showing the pattern of the first color electrodes 14A, 14B and first optical filler layer 18 across the OLED array, specifically how the patterning eliminates spacing between OLED devices in the OLED array.

[0175] FIG. 11I shows the deposition of a second optical filler layer 20 partially on the first optical filler layer 18 and partially on the first color electrode 14A to form an overlap region 80A. The second optical filler layer 20 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows designers to precisely adjust the layer thickness during deposition. The overlap region 80A provides tolerances that mitigate alignment errors in manufacturing, thereby increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layers remain intact on the substrate 10.

[0176] 11J shows second color vias 24 formed by dry etching using reactive ion etching through first optical filler layer 18, second optical filler layer 20, and DBR 12. The first color electrodes 14A, 14B, first color vias 16A, 16B, and DBR 12 layers remain intact on substrate 10.

[0177] 11K shows the deposition, by sputtering, of a second color electrode 22 onto the second optical filler layer 20, with the width of the second color electrode 22 approximately equal to the width of the second optical filler layer 20. A second color via 24 provides electrical connection of the second color electrode 22 to the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layer remain intact on the substrate 10.

[0178] 11L shows a top view of the embodiment after deposition of second color electrode 22. The patterning of first color electrodes 14A, 14B, and second color electrode 22 and first optical filler layer 18, upon which the third electrode will eventually be deposited, allows for minimal spacing between OLED optical microcavity devices on the OLED array.

[0179] 11M-11P show a series of photolithography steps for patterning the third optical filler layer. Photolithography is a widely used manufacturing technique, and it is understood that the steps as described in FIGS. 10D-10G may be repeated for the deposition of all optical filler layers disclosed herein.

[0180] FIG. 11M shows a cross-sectional view of the embodiment after deposition of photoresist 74. Deposition can be accomplished by spin-coating deposition. Photoresist 74 is deposited on a structure including a substrate 10 on which a DBR 12 is deposited, with first-color electrodes 14A and 14B stacked on the DBR 12 and connected to the substrate 10 by first-color vias 16A and 16B, respectively; a first optical filler layer 18 is deposited on the DBR 12; a second optical filler layer 20 and a second-color electrode 22 stacked on the first optical filler layer 18, with the second-color electrode 22 connected to the substrate 10 by a second-color via 24. A photomask is then applied with a design that includes opaque portions in the patterns of the first-color electrodes 14A and 14B and the second-color electrode 22, partially covering the first-color electrode 14B.

[0181] 11N, the structure with the photomask is exposed to UV light, which chemically changes the photoresist 74, making it soluble for etching in the clear areas of the photomask. In this embodiment, the photoresist 74 is a positive photoresist. The first optical filler layer 18, first color electrodes 14A, 14B, first color vias 16A, 16B, second optical filler layer 20, second color electrode 22, second color via 24, and DBR 12 layers remain intact on the substrate 10.

[0182] FIG. 11O illustrates the deposition of a third optical filler layer 58 on top of photoresist 74, which is deposited across the entire OLED array. The third optical filler layer 58 can be deposited by, for example, sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows designers to precisely control the layer thickness during deposition. The substrate 10 is then subjected to a stripping process that removes the photoresist 74 and the third optical filler layer 58 deposited on the photoresist 74. The stripper can be a commercially available product that fragments and removes the photoresist 74 without damaging the other layers underneath. The first optical filler layer 18, first color electrodes 14A, 14B, first color vias 16A, 16B, second optical filler layer 20, second color electrode 22, second color via 24, and DBR 12 layers remain intact on the substrate 10.

[0183] 11P shows the substrate 10 and its deposited layers after removing the remaining photoresist and the third optical filler layer 58 deposited on the photoresist. The remaining third optical filler layer 58 may partially cover the first optical filler layer 18 and the first color electrode 14B to form an overlap region 80C. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color via 24, and the DBR 12 layers remain intact on the substrate 10.

[0184] FIG. 11Q shows a fourth optical filler layer 60 deposited on the third optical filler layer 58, overlapping the second color electrode 22 to form an overlap region 80D. The fourth optical filler layer 60 can be deposited by, for example, sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows designers to precisely adjust the layer thickness during deposition. The overlap regions 80C and 80D can mitigate alignment errors in manufacturing and thus increase the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10. The first optical filler layer 18, first color electrodes 14A and 14B, first color vias 16A and 16B, second optical filler layer 20, second color electrode 22, second color via 24, and DBR 12 layers remain intact on the substrate 10.

[0185] 11R shows third color via 64 dry etched using reactive ion etching through first optical filler layer 18, third optical filler layer 58, fourth optical filler layer 60, and DBR 12. First optical filler layer 18, first color electrodes 14A, 14B, first color vias 16A, 16B, second optical filler layer 20, second color electrode 22, and second color via 24 remain intact on substrate 10.

[0186] 11S shows a third color electrode 62 deposited, for example by sputtering, on the fourth optical filler layer 60. The width of the third color electrode 62 is approximately equal to the width of the fourth optical filler layer 60. A third color via 64 provides electrical connection of the third color electrode 62 to the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color via 24, the third optical filler layer 58, and the DBR 12 remain intact on the substrate 10.

[0187] 11T shows a top view after deposition of the third color electrode 62. The patterning of the first color electrodes 14A, 14B, second color electrode 22, and third color electrode 62 allows for minimal spacing between OLED devices on the OLED array. The emitted color can be any color on the visible light spectrum, including, but not limited to, red, yellow, blue, and green. A preferred combination of a three-color arrangement is red, green, and blue emission.

[0188] FIG. 11U shows a white OLED stack 26 deposited across the entire OLED array. It is understood that the white OLED stack 26 shown in FIG. 11U comprises a series of layers, preferably composed of organic materials. Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, and inkjet printing. In this embodiment, thermal evaporation is the preferred method. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color vias 24, the third optical filler layer 58, the third color electrode 62, the third color vias 64, the fourth optical filler layer 60, and the DBR 12 remain intact on the substrate 10 beneath the white OLED stack 26.

[0189] Figure 11V shows the final step in the fabrication process: depositing a cathode 28 on the white OLED stack 26 to form the optical microcavities for each OLED device in the OLED array. The cathode 28 can be deposited by thermal evaporation and sputtering. In this embodiment, thermal evaporation is the preferred deposition method. The first optical filler layer 18, first color electrodes 14A, 14B, first color vias 16A, 16B, second optical filler layer 20, second color electrode 22, second color via 24, third optical filler layer 58, third color electrode 62, third color via 64, fourth optical filler layer 60, and DBR 12 remain intact on the substrate 10.

[0190] All publications, patents, and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains, and are hereby incorporated by reference. The reference to any prior art herein is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

[0191] The invention thus described will be obvious that it may be varied in many ways, and such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A substrate; a distributed Bragg reflector (DBR) on the substrate; a first color electrode on the DBR defining a first color microcavity, the first color electrode connected to the substrate through a first via; a first optical filler layer on the DBR adjacent to the first color electrode on the DBR; a second optical filler layer on the first optical filler layer and partially overlapping the first color electrode in an overlapping region; a second color electrode on the second optical filler layer that defines a second color microcavity, the second color electrode being connected to the substrate through a second via; a white organic light emitting diode (OLED) stack on the first color electrode and on the second color electrode; a top electrode on the white OLED stack; 1. An organic light-emitting diode device comprising:

2. The device of claim 1 , wherein the second color electrode partially overlaps the first color electrode.

3. 3. The device of claim 1, wherein the first color microcavity has a first color optical path length between the DBR and the top electrode through the first color electrode, and the second color microcavity has a second color optical path length between the DBR and the top electrode through the second color electrode.

4. 4. The device of claim 3, wherein the optical path length of the first color and the optical path length of the second color are adjusted to provide desired first color and second color pixels, respectively.

5. The device of claim 1 or 2, wherein the first optical filler layer and the second optical filler layer comprise a transparent polymer.

6. The device of claim 1 or 2, wherein the first optical filler layer and the second optical filler layer comprise a transparent inorganic dielectric.

7. 3. The device of claim 1, further comprising a pixel defining layer insulating the first color electrode from the second color electrode.

8. The device of claim 7 , wherein the pixel-defining layer comprises one or more of an inorganic insulating dielectric and an organic material.

9. The device of claim 1 or 2, wherein the substrate is a thin film transistor (TFT) substrate.

10. The device of claim 1 or 2, further comprising a second DBR on top of the top electrode.

11. 3. The device of claim 1, wherein the top electrode is a cathode and the bottom electrode is an anode.

12. 3. The device of claim 1, wherein the top electrode is an anode and the bottom electrode is a cathode.

13. over the second color electrode and below the white OLED stack; a third optical filler layer on the first optical filler layer defining microcavities of a third color; a fourth optical filler layer on the third optical filler layer and overlapping the second color electrode; a third color electrode on the fourth optical filler layer, overlapping the second color electrode and connected to the substrate through a third via; The device of claim 1 or 2, further comprising:

14. 1. A method for fabricating a multicolor microcavity organic light emitting diode (OLED) array, comprising: depositing a distributed Bragg reflector (DBR) on a substrate; depositing a first color electrode on the DBR that defines a first color microcavity, the first color electrode being connected to the substrate through a first via; depositing a first optical filler layer on the DBR adjacent to the first color electrode on the DBR; depositing a second optical filler layer on the first optical filler layer, the second optical filler layer partially overlapping the first color electrode in an overlapping region; depositing a second color electrode on the second optical filler layer that defines a second color microcavity, the second color electrode being connected to the substrate through a second via; depositing a white organic light emitting diode (OLED) stack on the first color electrode and above the second color electrode; depositing a top electrode on the white OLED stack; A method comprising:

15. The method of claim 14 , wherein the white OLED stack is deposited over the entire OLED array.

16. 16. The method of claim 14 or 15, wherein the white OLED stack is deposited using thermal evaporation, spin casting, or inkjet printing.

17. The method of claim 14 or 15, wherein the top electrode is deposited using thermal evaporation or sputtering.

18. 16. The method of claim 14 or 15, further comprising depositing a pixel defining layer that insulates the first color electrode from the second color electrode.

19. 20. The method of claim 18, wherein the pixel defining layer is deposited using sputtering, spin coating, thermal evaporation, chemical vapor deposition, atomic layer deposition, or spin casting.

20. 16. The method of claim 14 or 15, further comprising depositing a second DBR on the top electrode.

21. 16. The method of claim 14 or 15, wherein the first color electrode, the second color electrode, and the top electrode are deposited using sputtering, thermal evaporation, or spin coating.

22. 16. The method of claim 14 or 15, wherein the first and second optical filler layers are deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

23. 16. The method of claim 14 or 15, wherein the DBR is deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

24. Prior to depositing the white OLED stack, depositing a third optical filler layer selected for a third color on the first optical filler layer, the third optical filler layer overlapping the electrode of the first color; depositing a fourth optical filler layer selected for the third color on the third optical filler layer, the fourth optical filler layer overlapping the electrode of the second color; depositing a series of third color electrodes on the fourth optical filler layer; Further comprising:

16. The method of claim 14 or 15, wherein the white OLED stack is deposited on a sequence of the first color electrode, the second color electrode, and the third color electrode.

Images