A Micro OLED microcavity structure, its fabrication method, and OLED device

Abstract

This invention discloses a Micro OLED microcavity structure and its fabrication method, comprising the following steps: fabricating a pixel definition layer on a CMOS substrate; then fabricating R-reflective anodes, G-reflective anodes, and B-reflective anodes of different thicknesses; printing a layer of transparent conductive adhesive on the reflective anodes and pixel definition layer and curing it to form a transparent conductive layer; thinning the transparent conductive layer as a whole until the transparent conductive layer above the pixel definition layer disappears, forming transparent conductive layers of different thicknesses on the R-reflective anodes, G-reflective anodes, and B-reflective anodes respectively; fabricating a transparent anode on the transparent conductive layer, i.e., forming R-transparent anodes, G-transparent anodes, and B-transparent anodes on the transparent conductive layers on the R-reflective anodes, G-reflective anodes, and B-reflective anodes respectively; the method can achieve individual adjustment of the microcavity length for different colors, and the transparent anodes of different colors have the same height, facilitating subsequent processes.

Description

Technical Field

[0001] This invention belongs to the field of OLED display technology, specifically relating to a Micro OLED microcavity structure, its fabrication method, and an OLED device. Background Technology

[0002] In OLED products, the microcavity resonance effect is typically used to enhance the light emission of the display panel, where the microcavity length is the length between the reflecting anode and cathode. In full-color OLED products, color effects are generally synthesized using RGB colors. However, because different colors have different wavelengths, the required microcavity length for the corresponding OLED devices will also differ. In large-size full-color OLED devices, different fine metal masks (FMMs) can be used to deposit different colors of light-emitting devices, allowing for individual tuning of the device structure to adjust the microcavity. In the Micro OLED industry, due to the smaller pixel size, FMM technology is not applicable. Instead, the light-emitting material is deposited across the entire surface using an open mask to form a white light device, which is then filtered by a color filter to achieve the color effect.

[0003] Because it is a full-surface vapor deposition, the vapor deposition film thickness of the corresponding RGB pixels is consistent, and the microcavities of different colors cannot be adjusted individually. Therefore, the industry generally adjusts the microcavities by adjusting the thickness of the transparent anode corresponding to the RGB pixels. However, this results in inconsistent anode structure heights for the RGB pixels, which poses certain risks to the subsequent manufacturing processes, such as unevenness during spin coating.

[0004] For example, Chinese patent CN109742266A discloses a method for fabricating an OLED microcavity structure. This method includes the following steps: forming a reflective anode on a substrate; forming a transparent conductive film layer on the reflective anode with a thickness corresponding to the required pixel; patterning the transparent conductive film layer and the reflective anode using a pixel mask corresponding to the required pixel to form the pattern of the required pixel; and repeating the above steps on the obtained structure surface according to display requirements until the pixel display structure required by the display device is obtained. This patent adjusts the microcavity by adjusting the thickness of the transparent anode corresponding to the RGB pixels. However, this can lead to inconsistent heights of the RGB anode structure, posing certain risks to subsequent fabrication processes, such as unevenness during spin coating. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a Micro OLED microcavity structure and its fabrication method. The method utilizes an anode structure consisting of a reflective anode, a transparent conductive layer, and a transparent anode. By setting the reflective anode to different thicknesses and then adjusting the microcavity through the transparent conductive layer, the height of the transparent anode is ensured to be consistent, facilitating subsequent processes. This method also allows for individual adjustment of the length of microcavities for different colors.

[0006] The present invention also provides an OLED device comprising the Micro OLED microcavity structure described herein.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for fabricating a Micro OLED microcavity structure, the method comprising the following steps:

[0009] (1) Fabricate a pixel definition layer on a CMOS substrate;

[0010] (2) Repeat the photolithography process multiple times to prepare R-reflective anodes, G-reflective anodes, and B-reflective anodes of different thicknesses;

[0011] (3) Print a layer of transparent conductive adhesive on the reflective anode and pixel definition layer and cure it to form a transparent conductive layer;

[0012] (4) The transparent conductive layer is thinned as a whole until the transparent conductive layer above the pixel definition layer disappears, thus forming transparent conductive layers of different thicknesses above the R reflective anode, G reflective anode and B reflective anode respectively.

[0013] (5) A transparent anode is prepared on the transparent conductive layer, that is, R transparent anode, G transparent anode and B transparent anode are formed on the transparent conductive layer on the R reflective anode, G reflective anode and B reflective anode respectively;

[0014] (6) The subsequent organic functional layer and cathode are prepared by vapor deposition process.

[0015] The height of the pixel definition layer is higher than the height of the reflective anode.

[0016] The material of the reflective anode is any one or more of molybdenum, aluminum, and silver.

[0017] The transparent conductive adhesive is made of nano-silver paste.

[0018] The thickness of the transparent anode is 10-100 nm.

[0019] The transparent anode is made of any one or more of ITO, IGZO, and IZO.

[0020] In step (3), the printing is inkjet printing.

[0021] In step (4), the material is thinned by dry engraving.

[0022] The present invention also provides a Micro OLED microcavity structure prepared according to the preparation method described in the present invention, wherein the length of the microcavity for different colors can be adjusted individually.

[0023] This invention provides a method for fabricating a Micro OLED microcavity structure. First, a pixel definition layer is fabricated on a CMOS substrate. Then, a photolithography process is repeated multiple times to fabricate R-reflective anodes, G-reflective anodes, and B-reflective anodes of different thicknesses, all lower than the pixel definition layer. Next, transparent conductive layers with the same surface height as the pixel definition layer are formed on the R-reflective anodes, G-reflective anodes, and B-reflective anodes using inkjet printing and dry etching processes, respectively. Finally, a transparent anode is fabricated on top of the transparent conductive layer, forming an anode structure of reflective anode + transparent conductive layer + transparent anode. This invention ensures consistent transparent anode height by setting different thicknesses for the reflective anodes and adjusting the microcavity through the transparent conductive layer, facilitating subsequent processes. This method also allows for individual adjustment of the length of microcavities for different colors. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the Micro OLED microcavity structure in this invention;

[0025] Figure 2 A process flow diagram for fabricating the microcavity structure of Micro OLED;

[0026] In the diagram, 100 - substrate, 110R - red light reflecting anode, 110G - green light reflecting anode, 110B - blue light reflecting anode, 120 - transparent conductive layer, 120R - red light transparent conductive layer, 120G - green light transparent conductive layer, 120B - blue light transparent conductive layer, 130R - red light transparent anode, 130G - green light transparent anode, 130B - blue light transparent anode, 140 - pixel definition layer, 150 - organic functional layer, 150 - cathode. Detailed Implementation

[0027] The present invention will be described in detail below with reference to the embodiments.

[0028] A method for fabricating a Micro OLED microcavity structure includes the following steps:

[0029] (1) A CMOS driving circuit is fabricated on a silicon wafer substrate to form a CMOS substrate 100, and a pixel definition layer PDL 140 is fabricated on the CMOS substrate by photolithography. The material of the pixel definition layer can be polyimide-based, acrylic-based organic materials or SiN, SiON, SiO inorganic materials.

[0030] (2) Repeat the photolithography process multiple times to prepare R-reflective anode 110R, G-reflective anode 110G, and B-reflective anode 110B with different thicknesses; the material of the reflective anode can be any one or more of Al, Ag, and Mo;

[0031] (3) A layer of transparent conductive adhesive is printed on the reflective anode and pixel definition layer by inkjet printing and cured to form a transparent conductive layer 120;

[0032] (4) The transparent conductive layer is thinned by dry etching until the transparent conductive layer above the pixel definition layer disappears, thus forming transparent conductive layers 120R, 120G and 120B of different thicknesses on the R reflective anode, G reflective anode and B reflective anode respectively.

[0033] (5) A transparent anode is prepared on the transparent conductive layer by photolithography, that is, R transparent anode 130R, G transparent anode 130G and B transparent anode 130B are formed on the transparent conductive layer on the R reflective anode, G reflective anode and B reflective anode respectively; the material of the transparent anode can be any one or more of ITO, IGZO and IZO.

[0034] (6) Using an open mask, the subsequent organic functional layer 150 and cathode 160 are prepared by vapor deposition process; the cathode material can be any one or more of Mg, Ag and Al.

[0035] The above preparation method allows for individual adjustment of the microcavity length for different colors, and ensures that the height of the transparent anodes of different colors is consistent, which facilitates subsequent processes.

[0036] The above detailed description of a Micro OLED microcavity structure, its fabrication method, and OLED device with reference to the embodiments is illustrative rather than limiting. Several embodiments can be listed within the defined scope. Therefore, variations and modifications without departing from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A method for fabricating a Micro OLED microcavity structure, characterized in that, The preparation method includes the following steps: (1) Fabricate a pixel definition layer on a CMOS substrate; (2) Repeat the photolithography process multiple times to prepare R-reflective anodes, G-reflective anodes, and B-reflective anodes of different thicknesses; (3) Print a layer of transparent conductive adhesive on the reflective anode and pixel definition layer and cure it to form a transparent conductive layer; (4) The transparent conductive layer is thinned as a whole until the transparent conductive layer above the pixel definition layer disappears, thus forming transparent conductive layers of different thicknesses above the R reflective anode, G reflective anode and B reflective anode respectively. (5) A transparent anode is prepared on the transparent conductive layer, that is, R transparent anode, G transparent anode and B transparent anode are formed on the transparent conductive layer on the R reflective anode, G reflective anode and B reflective anode respectively; (6) The subsequent organic functional layer and cathode are prepared by vapor deposition process.

2. The preparation method according to claim 1, characterized in that, The height of the pixel definition layer is higher than the height of the reflective anode.

3. The preparation method according to claim 1, characterized in that, The material of the reflective anode is any one or more of molybdenum, aluminum, and silver.

4. The preparation method according to claim 1, characterized in that, The transparent conductive adhesive is made of nano-silver paste.

5. The preparation method according to claim 1, characterized in that, The thickness of the transparent anode is 10-100 nm.

6. The preparation method according to claim 1, characterized in that, The transparent anode is made of any one or more of ITO, IGZO, and IZO.

7. The preparation method according to claim 1, characterized in that, In step (3), the printing is inkjet printing.

8. The preparation method according to claim 1, characterized in that, In step (4), the material is thinned by dry engraving.

9. The Micro OLED microcavity structure prepared by the preparation method according to any one of claims 1-8.

10. An OLED device, characterized in that, The OLED device contains the Micro OLED microcavity structure as described in claim 9.

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