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CN-118266283-B - Multicolor OLED array for high aperture display

CN118266283BCN 118266283 BCN118266283 BCN 118266283BCN-118266283-B

Abstract

A microcavity pixel design and fabrication method for high aperture ratio Organic Light Emitting Diode (OLED) arrays suitable for light field displays. This is achieved by laterally overlapping the intermediate electrode and the optical filler layer, reducing the lateral spacing. The OLED layers in this design have a uniform white OLED stack, allowing each layer to be deposited on the OLED array, simplifying the manufacturing process. The optical path length of each sub-pixel optical microcavity is optimized by the thickness of the optical filler layer, so that the white OLED stack remains uniform, thereby reducing manufacturing complexity.

Inventors

  • CHENG JIAQI
  • J. Peckham

Assignees

  • 阿瓦龙全息照相技术股份公司

Dates

Publication Date
20260512
Application Date
20220621
Priority Date
20210716

Claims (20)

  1. 1. An organic light emitting diode device comprising: A substrate; A Distributed Bragg Reflector (DBR) on the substrate; A first color electrode located on the distributed bragg reflector and defining a first color microcavity, the first color electrode being connected to the substrate through a first through-hole; A first optical filler layer located on the distributed bragg reflector and adjacent to the first color electrode on the distributed bragg reflector; the first optical filler layer is transparent to visible light and electrically insulating; a second optical filler layer on the first optical filler layer and partially overlapping the first color electrode in an overlapping region; the second optical filler layer is transparent to visible light and electrically insulating; a second color electrode on the second optical filler layer and defining a second color microcavity, the second color electrode being connected to the substrate through a second through-hole; A white Organic Light Emitting Diode (OLED) stack over the first color electrode and the second color electrode, and A top electrode over the white organic light emitting diode stack.
  2. 2. The device of claim 1, wherein the second color electrode partially overlaps the first color electrode.
  3. 3. The device of claim 1 or 2, wherein the first color microcavity has a first color optical path length passing through the first color electrode between the distributed bragg reflector and the top electrode, and the second color microcavity has a second color optical path length passing through the second color electrode between the distributed bragg reflector and the top electrode.
  4. 4. A device according to claim 3, wherein the first and second colour optical path lengths are adjusted to provide the required first and second colour pixels respectively.
  5. 5. The device of claim 1 or 2, wherein the first and second optical filler layers comprise transparent polymers.
  6. 6. The device of claim 1 or 2, wherein the first and second optical filler layers comprise transparent inorganic dielectrics.
  7. 7. The device of claim 1 or 2, further comprising a pixel defining layer insulating the first color electrode from the second color electrode.
  8. 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. 9. The device of claim 1 or 2, wherein the substrate is a Thin Film Transistor (TFT) substrate.
  10. 10. The device of claim 1 or 2, further comprising a second distributed Bragg reflector over the top electrode.
  11. 11. The device of claim 1 or 2, wherein the top electrode is a cathode and the first color and the second color electrodes are anodes.
  12. 12. The device of claim 1 or 2, wherein the top electrode is an anode and the first color and the second color electrodes are cathodes.
  13. 13. The device of claim 1 or 2, further comprising a white organic light emitting diode stack located over the second color electrode and under the white organic light emitting diode stack: A third optical filler layer on the first optical filler layer and defining a third color microcavity; A fourth optical filler layer on the third optical filler layer, the fourth optical filler layer partially overlapping the second color electrode, and And a third color electrode on the fourth optical filler layer and partially overlapping the second color electrode, the third color electrode being connected to the substrate through a third via hole.
  14. 14. A method for fabricating a multi-color microcavity organic light-emitting diode (OLED) array, the method comprising: depositing a Distributed Bragg Reflector (DBR) on the substrate; depositing a first color electrode on the distributed bragg reflector, the first color electrode defining a first color microcavity, the first color electrode being connected to the substrate through a first through-hole; depositing a first optical filler layer on the distributed bragg reflector, the first optical filler layer being adjacent to the first color electrode on the distributed bragg reflector; 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, the second color electrode defining a second color microcavity, the second color electrode being connected to the substrate through a second through-hole; Depositing a white organic light emitting diode stack over the first color electrode and the second color electrode, and A top electrode is deposited over the white organic light emitting diode stack.
  15. 15. The method of claim 14, wherein the white organic light emitting diode stack is deposited over an entire organic light emitting diode array.
  16. 16. The method of claim 14 or 15, wherein the white organic light emitting diode stack is deposited using thermal evaporation, spin coating, or inkjet printing.
  17. 17. The method of claim 14 or 15, wherein the top electrode is deposited using thermal evaporation or sputtering.
  18. 18. The method of claim 14 or 15, further comprising depositing a pixel defining layer insulating the first color electrode from the second color electrode.
  19. 19. 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. 20. The method of claim 14 or 15, further comprising depositing a second distributed Bragg reflector DBR on the top electrode.

Description

Multicolor OLED array for high aperture display Cross Reference to Related Applications The present application claims priority from U.S. patent application Ser. No. 17/378,300, filed on 7/16 of 2021, the entire contents of which are incorporated herein by reference. Technical Field The present invention relates to a patterning design and manufacturing method of an Organic Light Emitting Diode (OLED) device with a high aperture suitable for a light field display. Background The light field display provides multiple views, allowing the user to receive a separate view in each eye. While current such displays provide an interesting viewing experience, attractive light field displays require very high pixel densities, very small angular distances between views, and large viewing angles. It is desirable for the user to experience a smooth transition between viewing regions while maintaining independent and perceptible views from adjacent views. The basic requirement for achieving these viewing parameters is to control the output characteristics of the emission source. An Organic Light Emitting Diode (OLED) bound in the microcavity can control the spectral bandwidth and output angle of the generated light. One method for controlling the output characteristics of light is through the use of microcavities. The microcavity is formed between two mirrors or reflective surfaces, which may be, for example, a layered stack of metal anodes, metal cathodes, or non-absorbing materials, which may be a Distributed Bragg Reflector (DBR). Mirrors are used to reflect light over a range of wavelengths while generally preserving the physical properties of the incident light. Two major design variables that affect microcavity output characteristics are the reflectivity of the top and bottom surfaces (i.e., opposing mirrors) and the optical path length Λ. The wavelength of the light output by such an OLED structure depends in part on the optical path length of the microcavity. The optical path length may be manipulated by adjusting the thickness and/or number of layers comprising the microcavity. When manufacturing OLEDs of a size suitable for light field displays, challenges arise in depositing the organic layers individually to achieve the thickness required for the desired optical path length for each color. One challenge faced in fabricating OLEDs suitable for use in light field displays is achieving a high aperture ratio of pixels less than 10 μm using existing fabrication capabilities. The aperture ratio of a pixel is the ratio of the light emitting area of the pixel to the total area of the display. A high aperture ratio can be achieved by maximizing the light emitting area of each pixel on the display. This reduces gaps in the display area, thereby improving the image quality of the light field display. Achieving high aperture ratios is particularly challenging when manufacturing high resolution displays of small pixel size. U.S. patent application publication No. US2021/0057670 to Wong et al describes a light emitting OLED pixel array. The disclosed pixel uses multiple transparent or substantially transparent dielectric layers on each anode. The thickness of the dielectric layer is designed to optimize the emission of light of the desired color for the pixel. The white OLED layer is formed in a single deposition step of the OLED array, with lateral spacing between each anode resulting in a reduced aperture ratio. U.S. patent 10,790,473 to Park et al describes an OLED device designed to achieve high aperture ratios. The high aperture ratio is achieved by first connecting the reflective and transparent electrodes of the anode at the corners of the sub-pixel area. Each sub-pixel has a microcavity structure, thereby minimizing the pixel defining layers between sub-pixels. The spacing between sub-pixels is not preferred for light field displays because the light emitting area of the display is not maximized. High aperture ratios are preferred for near-eye displays such as Virtual Reality (VR) displays, augmented Reality (AR) displays, micro-displays, and light field displays. There remains a need for a micron-sized OLED pixel array design and fabrication method that can achieve high aperture ratios at high display resolutions suitable for light field displays. This background information is provided for the purpose of making known to the applicant information that may be relevant to the present invention. It is not necessarily an admission that any of the preceding information constitutes prior art against the present invention. Disclosure of Invention It is an object of the present disclosure to provide an optical microcavity pixel device including an Organic Light Emitting Diode (OLED) and a photolithographic patterning method that achieves a micron-sized pixel that achieves an aperture ratio of greater than 70% when patterned in an array. It is another object of the present disclosure to provide an OLED array patterning metho