Quantum dot pixel unit substrate and preparation method and application thereof

Abstract

The invention discloses a quantum dot pixel unit substrate and a preparation method and application thereof, and belongs to the field of micro display. The quantum dot pixel unit substrate comprises a substrate, a reflective retaining wall, a patterned quantum dot color conversion layer and an oxide layer, a reflective retaining wall and a patterned quantum dot color conversion layer are arranged on the substrate; the patterned quantum dot color conversion layer comprises a patterned blue light diffusion particle permeation layer, a patterned red quantum dot conversion layer and a patterned green quantum dot conversion layer; the patterned blue light diffusion particle penetration layer, the patterned red quantum dot conversion layer and the patterned green quantum dot conversion layer are separated through reflective retaining walls respectively; and an oxide layer is arranged on the reflective retaining wall and the patterned quantum dot color conversion layer. The quantum dot pixel unit substrate has a light isolation function, and solves the problem that in the prior art, light crosstalk is easily caused between quantum dot pixel units, and then the display resolution is reduced.

Description

Technical Field

[0001] The present application relates to a quantum dot pixel unit substrate and a preparation method and application thereof, belonging to the field of microdisplay. Background Art

[0002] Micro-LED displays have obvious advantages in terms of display resolution and contrast. Currently, the luminous efficiency of blue and green LED chips is relatively high, while the luminous efficiency of red LED chips is very low when the size is below 50 microns, and the smaller the size of the red chip, the lower the luminous efficiency. It is still difficult to achieve full-color Micro-LED displays.

[0003] Using blue LED chips to stimulate integrated patterned red and green quantum dots, full-color display can be achieved through quantum dot color conversion, which is currently a solution that can achieve full-color display. The specific plan is as follows: multiple quantum dot pixel units are distributed on the quantum dot pixel layer substrate, corresponding to the blue LEDs one by one. Under the excitation of the blue LED, the quantum dot pixel units can emit red light, green light, and the blue light transmitted by the blank pixel units. However, optical crosstalk will occur between the individual pixel units, resulting in a reduction in the display resolution of the microdisplay. Therefore, it is necessary to optically isolate the pixels to prevent optical crosstalk between the pixel units.

[0004] Therefore, it is necessary to develop an optically isolated quantum dot pixel unit substrate to prevent crosstalk. Summary of the invention

[0005] According to one aspect of the present application, a quantum dot pixel unit substrate is provided, in which a patterned quantum dot color conversion layer is separated by a reflective baffle and has a light isolation function, thereby solving the problem in the prior art that quantum dot pixel units are prone to light crosstalk, thereby causing a decrease in display resolution.

[0006] On one hand, the present application provides a quantum dot pixel unit substrate, including a substrate, a reflective baffle, a patterned quantum dot color conversion layer, and an oxide layer;

[0007] The substrate is provided with a reflective baffle and a patterned quantum dot color conversion layer;

[0008] The patterned quantum dot color conversion layer includes a patterned blue light diffusion particle transmission layer, a patterned red quantum dot conversion layer, and a patterned green quantum dot conversion layer;

[0009] The patterned blue light diffusion particle transmission layer, the patterned red quantum dot conversion layer, and the patterned green quantum dot conversion layer are separated by reflective retaining walls respectively;

[0010] The thickness of the patterned quantum dot color conversion layer is no greater than the thickness of the reflective baffle wall;

[0011] An oxidation layer is arranged on the reflective retaining wall and the patterned quantum dot color conversion layer.

[0012] Optionally, the reflective baffles are distributed in a patterned matrix, which has the effects of light isolation and reflection.

[0013] Optionally, the reflective blocking wall is a photoresist blocking wall and / or a metal blocking wall.

[0014] Optionally, the reflective baffle is black and / or silver in color.

[0015] Optionally, the oxide in the oxide layer includes any one or more of SiO2, Al2O3, and ZrO2.

[0016] Optionally, the oxide layer has a thickness of 0.01 to 1 micrometer.

[0017] Optionally, the patterned quantum dot color conversion layer has a thickness of 1 to 15 μm.

[0018] Optionally, the width of the patterned quantum dot color conversion layer is 2 to 20 μm.

[0019] Optionally, the cross-section of the patterned quantum dot color conversion layer is rectangular.

[0020] Optionally, the cross-section of the patterned quantum dot color conversion layer is square.

[0021] In another aspect, the present application provides a method for preparing the quantum dot pixel unit substrate, comprising the following steps:

[0022] (1) preparing a reflective retaining wall on a substrate;

[0023] (2) spin coating quantum dot glue on the side with the reflective baffle, exposing and curing, to obtain a quantum dot glue layer;

[0024] (3) depositing oxide on the quantum dot glue layer and the reflective retaining wall to obtain an oxide layer;

[0025] (4) preparing a mask on a local surface of the oxide layer and etching away the oxide layer in the area not protected by the mask;

[0026] (5) etching the quantum dot glue layer exposed in step II to obtain a single-color patterned quantum dot color conversion layer;

[0027] (6) Repeat steps (2) to (5) to prepare other two patterned quantum dot color conversion layers of different colors to obtain a quantum dot pixel unit substrate;

[0028] The patterned quantum dot color conversion layer includes a patterned blue light diffusion particle transmission layer, a patterned red quantum dot conversion layer, and a patterned green quantum dot conversion layer;

[0029] The thickness of the quantum dot glue layer is not greater than the thickness of the reflective baffle wall.

[0030] Optionally, the reflective baffles are distributed in a patterned matrix.

[0031] Optionally, the reflective blocking wall is a photoresist blocking wall and / or a metal blocking wall.

[0032] Optionally, the reflective baffle is black and / or silver in color.

[0033] Optionally, step (2) includes:

[0034] (2-1) Spin-coating quantum dot glue on the side with the reflective baffle wall, exposing and curing, wherein the thickness of the quantum dot glue layer after curing is greater than the thickness of the reflective baffle wall;

[0035] (2-2) thinning the obtained quantum dot glue layer so that the thickness of the quantum dot glue layer is no greater than the height of the reflective baffle wall;

[0036] or,

[0037] The quantum dot glue is spin-coated on the side with the reflective baffle wall and cured, so that the thickness of the quantum dot glue layer after curing is not greater than the thickness of the reflective baffle wall.

[0038] Optionally, the thinning process is carried out by etching III and / or polishing.

[0039] Optionally, etching III is dry etching.

[0040] Optionally, the proportion of the solvent in the quantum dot glue can be controlled so that the thickness of the quantum dot glue layer after curing is not greater than the thickness of the reflective baffle wall.

[0041] Optionally, the method for preparing the mask includes: coating a photoresist on a local surface of the oxide layer, exposing and developing, and obtaining the mask.

[0042] Optionally, the photoresist is selected from any one or more of S1813, SPR220i, and AZP4620 series.

[0043] Optionally, the mask layer has a thickness of 1 to 20 μm.

[0044] Optionally, in step (4), the etching method I is dry etching.

[0045] Optionally, the dry etching is ICP etching.

[0046] Optionally, the conditions of ICP etching are: temperature 20-50° C., etching power 500-1000 W, RF power 50-200 W, chamber pressure 2-8 mTorr, etching speed (0.1-0.5) μm / min, and etching gas selected from any one or more of Ar2, Cl2, mixed gas A, and mixed gas B;

[0047] The mixed gas B is a mixed gas of Cl2, H2, CH4, and BCl3;

[0048] The mixed gas A is a mixed gas of H2 and O2.

[0049] Optionally, the etching power is 800-1000 W, and the radio frequency power is 100-150 W. A suitable ratio of etching power to radio frequency power can effectively improve the etching rate and depth ratio.

[0050] Optionally, the etching gas is a mixed gas B.

[0051] Optionally, in the mixed gas B, the gas flow rate of Cl2 is 10 to 15 sccm.

[0052] Optionally, in the mixed gas B, the flow ratio of Cl2 to H2 is 1:(1-5), the flow ratio of Cl2 to CH4 is 1:(1-5); the flow ratio of Cl2 to BCl3 is 1:(1-5); preferably, in the mixed gas B, the flow ratio of Cl2 to H2 is 1:2, the flow ratio of Cl2 to CH4 is 1:2; the flow ratio of Cl2 to BCl3 is 1:2.

[0053] Preferably, the ICP etching speed is 0.2 μm / min.

[0054] Optionally, after ICP etching, about 0.1 to 0.5 microns of photoresist remain on the surface, and the remaining photoresist is removed together in the subsequent acetone solvent soaking step.

[0055] Optionally, in step (5), etching II is wet etching.

[0056] Optionally, the wet etching method comprises: immersing the material obtained in step (4) in a solvent.

[0057] Optionally, the solvent is acetone.

[0058] Optionally, when the reflective retaining wall is a photoresist retaining wall, step (1) includes: coating a reflective photoresist on the substrate, exposing, curing, and developing using a photomask to form the reflective retaining wall.

[0059] Optionally, when the reflective retaining wall is a metal retaining wall, step (1) includes: photolithography of a photoresist on the substrate, deposition of metal, etching IV, and forming the reflective retaining wall;

[0060] or,

[0061] The method comprises: depositing reflective metal on a substrate, photolithography of positive photoresist, intermittently curing the positive photoresist in the length direction of the substrate, developing, and forming positive photoresist patterning; and performing reflective metal etching IV on the removed part of the positive photoresist to form a reflective retaining wall.

[0062] Optionally, the reflective metal is deposited by thermal evaporation and / or magnetron sputtering.

[0063] Optionally, the reflective metal is selected from any one or more of Ti, Ni, Al, Ag, Cr, and Pt.

[0064] Optionally, etching IV is lift-off etching and / or ICP etching.

[0065] Optionally, the reflective photoresist includes, by weight, 30-60 parts of organic solvent A, 5-10 parts of auxiliary agent A, 2-8 parts of resin derivative A, 3-10 parts of photosensitive agent A, and 10-20 parts of reflective material.

[0066] Optionally, the organic solvent A is PGMEA.

[0067] Optionally, the auxiliary agent A includes at least a crosslinking agent A.

[0068] Optionally, the reflective material is aluminum silver paste or nano titanium dioxide.

[0069] Optionally, the quantum dot glue layer has a thickness of 1 to 15 μm.

[0070] Optionally, the width of the quantum dot glue layer is 2 to 20 μm.

[0071] Optionally, the cross-section of the quantum dot glue layer is rectangular;

[0072] Optionally, the cross-section of the quantum dot glue layer is square.

[0073] Optionally, the quantum dot glue is selected from any one of diffuse particle glue, green quantum dot glue, and red quantum dot glue.

[0074] Optionally, the diffusion particle glue includes 10 to 20 parts of diffusion particles, 30 to 60 parts of organic solvent B, 5 to 15 parts of auxiliary agent B, 2 to 25 parts of resin derivative B, and 2 to 10 parts of photosensitizer A, in parts by weight.

[0075] Optionally, the organic solvent B is PGMEA.

[0076] Optionally, the auxiliary agent B includes at least a cross-linking agent B.

[0077] Optionally, the diffusion particles are selected from any one or more of barium sulfate, nano zinc oxide, nano silicon dioxide, nano titanium dioxide, PMMA microspheres, silicone microspheres, polytetrafluoroethylene wax, polypropylene wax, polyethylene wax microspheres, polyamide wax microspheres, and amide-modified polyethylene wax.

[0078] Optionally, the red quantum dot glue and the green quantum dot glue independently include 10 to 30 parts of quantum dots, 20 to 40 parts of organic solvent C, 5 to 20 parts of auxiliary agent C, 5 to 25 parts of resin derivative C, and 2 to 5 parts of photosensitizer B, respectively, by weight.

[0079] Optionally, the organic solvent C is PGMEA.

[0080] Optionally, the auxiliary agent C includes at least a crosslinking agent C.

[0081] Optionally, the quantum dots contain at least one element from groups IV, II-VI, IV-VI, and III-V.

[0082] Optionally, the quantum dots include perovskite quantum dots.

[0083] Optionally, the perovskite quantum dots are inorganic perovskite quantum dots and / or organic-inorganic hybrid perovskite quantum dots.

[0084] Optionally, in step (3), the deposition method is selected from any one or more of atomic layer deposition, magnetron sputtering deposition, and chemical vapor deposition.

[0085] Optionally, the oxide includes any one or more of SiO2, Al2O3, and ZrO2.

[0086] Optionally, the oxide layer has a thickness of 0.01 to 1 micrometer.

[0087] Another aspect of the present invention provides an application of the quantum dot pixel unit substrate in a Micro-LED micro display.

[0088] The beneficial effects of this application include:

[0089] The quantum dot pixel unit substrate provided in the present application has a light isolation function, and no light crosstalk occurs between the pixel units, thereby improving the display resolution of the microdisplay and solving the light crosstalk problem of the quantum dot color conversion layer in the preparation process of full-color Micro / Mini LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 This is a flow chart of the method for preparing the quantum dot pixel unit substrate of the present application;

[0091] Figure 2The structure diagram of the process product and the final product corresponding to the preparation method of the quantum dot pixel unit substrate of this application;

[0092] Figure 3 This is a diagram of the quantum dot pixel unit substrate for this application.

[0093] List of parts and reference numerals:

[0094] 1 substrate 2 reflective retaining wall 3 quantum dot glue layer

[0095] 4 oxide layer 5 mask layer

[0096] 6Patterned red quantum dot conversion layer

[0097] 7Patterned Green Quantum Dot Conversion Layer

[0098] 3-1 Blue light diffusion particle transmission layer DETAILED DESCRIPTION

[0099] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0100] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0101] Figure 1 The flowchart of the method for preparing the quantum dot pixel unit substrate includes the following steps:

[0102] Step S1, preparing reflective retaining walls with a patterned matrix distribution on a substrate.

[0103] Step S2, spin-coating quantum dot glue on the entire surface with the reflective baffle, and exposing and curing.

[0104] Step S3, using dry etching or polishing technology to thin the thickness of the quantum dot glue layer on the entire surface to make it flush with the thickness of the reflective baffle wall, thereby preparing a quantum dot glue layer.

[0105] Step S4, chemical vapor deposition CVD or ALD deposits a dense oxide to obtain an oxide layer to protect the quantum dots from being affected during subsequent operations.

[0106] Step S5, coating photoresist on the oxide layer, exposing and developing, making a mask, and dry etching to remove the oxide layer in the area not protected by the mask, exposing the quantum dot glue layer underneath.

[0107] Step S6, solvent immersion, wet removal of the exposed quantum dot glue, achieving patterning of the quantum dot glue at the target position, and obtaining a blue light diffusion particle transmission layer.

[0108] Step S7, repeating steps S2 to S6, replacing the glue with red quantum dot glue and green quantum dot glue in turn, achieving patterning of different quantum dot glues, and completing the preparation of a quantum dot pixel unit substrate with light isolation function.

[0109] After each step, the corresponding process products and final products are shown in Figure 2 .

[0110] Example

[0111] The preparation method of the quantum dot pixel unit substrate comprises the following specific steps:

[0112] S1, preparing a patterned matrix retaining wall on a substrate.

[0113] S2, mix 20wt% diffusion particles 100nm TiO2, 40wt% organic solvent PGMEA, 15wt% dicyclopentenyl acrylate, 20wt% ethoxylated trimethylolpropane triacrylate, and 5wt% photosensitizer (819 photoinitiator) (including 0.8g of diffusion particle nano titanium dioxide) to obtain light diffusion glue, spin-coat it on the entire surface with patterned matrix retaining walls, and expose and cure it.

[0114] S3, thinning the thickness by dry etching so that the quantum dot glue layer is the same thickness as the retaining wall.

[0115] S4, deposit 200nm SiO2 using CVD.

[0116] S5, using AZP4620 photoresist, exposure and development, making a photoresist mask; using ICP etching to remove SiO2 in the unprotected area;

[0117] Among them, the etching conditions are: etching power is 500W, RF power is 200W, chamber pressure is less than 8mTorr (specifically 7mTorr), etching gas is a mixture of Ar2 and Cl2; Ar2 gas flow rate is 20sccm, Cl2 gas flow rate is 10sccm; etching time is 2 minutes.

[0118] S6, soaking the obtained substrate in acetone to remove the exposed quantum dots, retaining the quantum dots in the protected area, and completing the preparation of the blue light diffusion particle transmission layer.

[0119] S7, repeat S2-S6 to prepare a patterned red quantum dot conversion layer and a patterned green quantum dot conversion layer, and complete the production of a patterned color conversion substrate.

[0120] Among them, the spin-coated red quantum dot glue includes: 20wt% red CdSe quantum dots, 40wt% organic solvent PGMEA, 20wt% dicyclopentenyl acrylate, 16wt% ethoxylated trimethylolpropane triacrylate, and 4wt% 819 photoinitiator. After exposure and curing, it serves as a patterned red quantum dot conversion layer, and emits red light after being excited by blue light; the spin-coated green quantum dot glue includes: 30wt% green CdSe quantum dots, 40wt% organic solvent PGMEA, 17wt% dicyclopentenyl acrylate, 8wt% ethoxylated trimethylolpropane triacrylate, and 5wt% 819 photoinitiator. After exposure and curing, it serves as a patterned green quantum dot conversion layer, and emits green light after being excited by blue light.

[0121] like Figure 3 , a quantum dot pixel unit substrate, comprising a substrate 1, a reflective retaining wall 2, a patterned quantum dot color conversion layer and an oxide layer 4;

[0122] The substrate 1 is provided with a reflective retaining wall 2 and a patterned quantum dot color conversion layer;

[0123] The patterned quantum dot color conversion layer includes a blue light diffusion particle transmission layer 3-1, a patterned red quantum dot conversion layer 6, and a patterned green quantum dot conversion layer 7;

[0124] The blue light diffusion particle transmission layer 3-1, the patterned red quantum dot conversion layer 6, and the patterned green quantum dot conversion layer 7 are separated by the reflective retaining wall 2 respectively;

[0125] The thickness of the patterned quantum dot color conversion layer is not greater than the thickness of the reflective baffle 2;

[0126] An oxide layer 4 is provided on the reflective retaining wall 2 and the patterned quantum dot color conversion layer;

[0127] The reflective retaining walls are distributed in a patterned matrix.

[0128] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A quantum dot pixel unit substrate, characterized in that: It includes a substrate, a reflective baffle, a patterned quantum dot color conversion layer and an oxide layer; The substrate is provided with a reflective baffle and a patterned quantum dot color conversion layer; The patterned quantum dot color conversion layer includes a patterned blue light diffusion particle transmission layer, a patterned red quantum dot conversion layer, and a patterned green quantum dot conversion layer; The patterned blue light diffusion particle transmission layer, the patterned red quantum dot conversion layer, and the patterned green quantum dot conversion layer are separated by reflective retaining walls respectively; The thickness of the patterned quantum dot color conversion layer is no greater than the thickness of the reflective baffle wall; An oxidation layer is arranged on the reflective retaining wall and the patterned quantum dot color conversion layer.

2. The quantum dot pixel unit substrate according to claim 1, characterized in that: The reflective retaining wall is distributed in a patterned matrix; Preferably, the reflective retaining wall is a photoresist retaining wall and / or a metal retaining wall; Preferably, the color of the reflective retaining wall is black and / or silver; Preferably, the oxide in the oxide layer is selected from any one or more of SiO2, Al2O3, and ZrO2; Preferably, the thickness of the oxide layer is 0.01 to 1 micrometer.

3. The quantum dot pixel unit substrate according to claim 1, characterized in that: The thickness of the patterned quantum dot color conversion layer is 1 to 15 μm; Preferably, the width of the patterned quantum dot color conversion layer is 2 to 20 μm; Preferably, the cross-section of the patterned quantum dot color conversion layer is rectangular; Preferably, the cross-section of the patterned quantum dot color conversion layer is a square.

4. A method for preparing a quantum dot pixel unit substrate according to any one of claims 1 to 3, characterized in that: The following steps are included: (1) preparing a reflective retaining wall on a substrate; (2) spin coating quantum dot glue on the side with the reflective baffle, exposing and curing, to obtain a quantum dot glue layer; (3) depositing oxide on the quantum dot glue layer and the reflective retaining wall to obtain an oxide layer; (4) preparing a mask on a local surface of the oxide layer and etching away the oxide layer in the area not protected by the mask; (5) etching the quantum dot glue layer exposed in step II to obtain a single-color patterned quantum dot color conversion layer; (6) Repeat steps (2) to (5) to prepare other two patterned quantum dot color conversion layers of different colors to obtain a quantum dot pixel unit substrate; The patterned quantum dot color conversion layer includes a patterned blue light diffusion particle transmission layer, a patterned red quantum dot conversion layer, and a patterned green quantum dot conversion layer; The thickness of the quantum dot glue layer is not greater than the thickness of the reflective baffle wall.

5. The method for preparing the quantum dot pixel unit substrate according to claim 4, characterized in that: The deposition method is selected from any one or more of atomic layer deposition, magnetron sputtering deposition, and chemical vapor deposition; Preferably, the oxide includes any one or more of SiO2, Al2O3, and ZrO2; Preferably, the thickness of the oxide layer is 0.01 to 1 micrometer; Preferably, the reflective baffles are distributed in a patterned matrix; Preferably, the reflective retaining wall is a photoresist retaining wall and / or a metal retaining wall; Preferably, the color of the reflective retaining wall is black and / or silver; Preferably, the thickness of the quantum dot glue layer is 1 to 15 μm; Preferably, the width of the quantum dot glue layer is 2 to 20 μm; Preferably, the cross-section of the quantum dot glue layer is rectangular; Preferably, the cross-section of the quantum dot glue layer is square.

6. The method for preparing the quantum dot pixel unit substrate according to claim 4, characterized in that: Step (2) comprises: (2-1) Spin-coating quantum dot glue on the side with the reflective baffle wall, exposing and curing, wherein the thickness of the quantum dot glue layer after curing is greater than the thickness of the reflective baffle wall; (2-2) thinning the obtained quantum dot glue layer so that the thickness of the quantum dot glue layer is no greater than the height of the reflective baffle wall; or, Spin-coating quantum dot glue on the side with the reflective baffle wall and curing the quantum dot glue layer so that the thickness of the cured quantum dot glue layer is no greater than the thickness of the reflective baffle wall; Preferably, the thinning treatment is carried out by etching III and / or polishing; Optionally, etching III is dry etching.

7. The method for preparing the quantum dot pixel unit substrate according to claim 4, characterized in that: The method for preparing a mask comprises: coating a photoresist on the surface of an oxide layer, exposing and developing the layer to obtain a mask; Preferably, the photoresist is selected from any one or more of S1813, SPR220i, and AZP4620 series; Preferably, the mask layer has a thickness of 1-20 μm.

8. The method for preparing the quantum dot pixel unit substrate according to claim 4, characterized in that: Etching II is wet etching; Preferably, the wet etching method comprises: immersing the material obtained in step (4) in a solvent; Preferably, the solvent is acetone.

9. The method for preparing the quantum dot pixel unit substrate according to claim 4, characterized in that: The method of etching I is dry etching; Preferably, the dry etching is ICP etching; Preferably, the conditions of ICP etching are: temperature 20-50° C., etching power 500-1000 W, RF power 50-200 W, chamber pressure 2-8 mTorr, etching speed 0.1-0.5 μm / min, and etching gas selected from any one or more of Ar2, Cl2, mixed gas A, and mixed gas B; The mixed gas B is a mixed gas of Cl2, H2, CH4, and BCl3; The mixed gas A is a mixed gas of H2 and O2.

10. An application of the quantum dot pixel unit substrate according to any one of claims 1 to 3 in a Micro-LED micro display.

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