Preparation of reticular quantum dot color conversion film and full-color Micro LED display device

Abstract

The invention discloses preparation of a reticular quantum dot color conversion film and a full-color Micro LED display device, and relates to the quantum dot technology, the color conversion film is prepared through quantum dot colloidal solution preparation, polymerization and cross-linking curing, the color conversion film is spin-coated on a blue light LED chip to obtain the high-resolution full-color Micro LED display device, the conception is novel, the design is ingenious, the process is simplified, and the production cost is reduced. The stability of the quantum dots is greatly improved, and the cost is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of quantum dots, and in particular relates to a color conversion film with a mesh quantum dot structure, and an LED display device using the color conversion film. Background Art

[0002] Quantum dots are a type of nanoscale semiconductor particles with unique optical and electronic properties. By adjusting the size of quantum dots during the preparation process, the wavelength of light emission can be controlled. They have controllable color, narrow emission bandwidth and high luminous efficiency, showing great potential in next-generation display applications.

[0003] In addition to being used as a self-luminous layer in electroluminescent devices, quantum dots can also be used as a color conversion layer for liquid crystal displays or LED displays. By converting the blue light emitted by blue LEDs through a quantum dot conversion layer, it is converted into red and green light, and then mixed with blue light to produce high-quality white light. This method significantly improves the color gamut coverage and display effect, and also reduces energy consumption. Quantum dot color conversion technology combined with Micro LED technology can achieve ultra-high resolution full-color high-brightness display. In addition, due to the stability and long life of quantum dots, more lasting color performance can be provided.

[0004] At present, quantum dot color conversion films are usually prepared by dispersing quantum dots in photoresist. However, as semiconductor nanocrystals, quantum dots are easily aggregated in photoresist composed of organic molecules, resulting in reduced luminescence performance of quantum dots, which in turn affects the resolution of the converted image of the prepared quantum dot color conversion film. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the present invention proposes a mesh quantum dot color conversion film, which achieves uniform distribution of quantum dots and ensures high resolution of the color conversion film.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions: A method for preparing a network quantum dot color conversion film comprises the following steps: S1: synthesize quantum dot colloidal solutions emitting red light and green light by hot injection method, and mix them evenly according to the proportion; S2: dissolving the polymer in an organic solvent to obtain a polymer solution, then adding the mixed quantum dot colloid solution to the polymer solution, heating and stirring to obtain a quantum dot polymer solution; S3: Add a small amount of photosensitizer to the quantum dot polymer solution, and heat and stir evenly on a heating plate at 40°C to obtain the final quantum dot solution; S4: The final quantum dot solution was spin-coated on the substrate for 40 seconds, and then irradiated with ultraviolet light for 120 seconds, with a wavelength of 365 nm and an intensity of 10 mW / cm 2 The polymer and the photosensitizer are cross-linked to form a network structure, and the quantum dots are embedded in the network polymer to prepare a network polymer quantum dot film.

[0007] In the present invention, the quantum dot colloidal solution synthesis process comprises the following steps: S1-1: preparing quantum dot materials, organic solvents, and surfactants, adding the organic solvents and surfactants into a reaction container, heating at a constant temperature and stirring to obtain a uniform reaction solution; S1-2: Injecting quantum dot materials into the reaction container in a certain proportion, keeping a constant temperature during injection, and keeping it for a certain time to allow the reaction to be complete; S1-3: After the reaction is completed, the mixture is cooled to room temperature to obtain a crude colloidal solution; S1-4: Centrifuge, wash, and disperse the crude colloidal solution to remove impurities and unreacted substances to obtain a quantum dot colloidal solution.

[0008] In the present invention, the raw materials required for the preparation process are, according to the final quantum dot solution, wherein the mass fraction of the quantum dot material is 1-10%, the mass fraction of the polymer is 85-92%, the mass fraction of the photosensitizer is 0.05-1%, and the mass fraction of the organic solvent is 5-10%.

[0009] In the present invention, the quantum dot material is II-VI quantum dots (for example: CdSe / ZnS, CdSe / CdS quantum dots, etc.), III-V quantum dots (for example: InP, GaAs quantum dots, etc.), perovskite quantum dots (for example: CsPbX3, CH3NH2Pb2X3 quantum dots, etc.), or the single-core nanoparticles of the above materials are coated with one or more layers including but not limited to CdS, ZnO, ZnS, ZnSe, ZnTe or any one or a combination of at least two of the alloy materials.

[0010] In the present invention, the organic solvent is a mixture of one or more of chloroform, toluene, chlorobenzene, alkanes, olefins, aromatic hydrocarbons, alcohols, ethyl acetate, halogenated alkanes, halogenated olefins, halogenated aromatic hydrocarbons, diol derivatives, and ketones.

[0011] In the present invention, the polymer is one of polycarbonate (PC), polypropylene (PP), polymethyl methacrylate (PMMA), polysiloxane polymer and polyalkylene oxide polymer.

[0012] In the present invention, the photosensitizer is one of hydrogen abstraction photosensitizers such as benzophenone and 2,4-dihydroxybenzophenone, or one of cleavage photosensitizers such as 2-hydroxy-2-methyl-1-phenylpropanone and 1-hydroxycyclohexylphenyl ketone, or one of cationic photosensitizers such as diazonium salts and diaryliodonium salts, or a mixture of at least two of the above three categories.

[0013] The mesh polymer quantum dot film produced by the above process is used as a color conversion film for full-color Micro LED.

[0014] A full-color Micro LED display device, comprising a multi-layer structure: substrate; The blue light-emitting chip is transferred to the substrate through transfer technology; A nickel film, deposited onto the substrate, fills the gap matrix between the blue light-emitting chips; A film of photoresist and graphene is spin-coated on top of the blue light-emitting chip layer; A color conversion film, a network polymer quantum dot film obtained by spin coating the final quantum dot solution; Filter layer.

[0015] The photoresist and graphene film is obtained by the following steps: heating and stirring the negative photoresist and graphene in an organic solvent, wherein the mass fraction of the negative photoresist is 20%-40%, the mass fraction of the graphene is 10-20%, and the mass fraction of the organic solvent is 40-70%. The mixed solution is spin-coated on a blue light-emitting chip at a speed of 2000 rpm for 10 seconds. After baking, the surface is flat and transparent, and the thickness ranges from 500nm to 2μm.

[0016] The color conversion film is obtained by the following steps: the final quantum dot solution is spin-coated on the photoresist and graphene film at a speed of 3000 rpm, the mask with a pixel size of 5μm*5μm is exposed to ultraviolet light for 120 seconds, and finally developed with a developer to obtain a patterned film. Patterning of different pixel sizes can be performed, with a maximum pixel size of 300×300 μm² (50 ppi) to a minimum pixel size of 5×5 μm² (3628 ppi), as well as different pixel pitches.

[0017] The filter layer is obtained by the following steps: firstly, a color resist layer photoresist film is formed by spin coating, and then a mask with a specific pattern is used for exposure and development to form a color resist layer pattern of the color; then the same method is repeated to form color resist layer patterns of the other two colors, and finally the filter layer is formed.

[0018] Compared with the prior art, this application has the following advantages: (1) The mesh quantum dot color conversion film of the present application does not use photoresist in the preparation process, thus avoiding the influence of photoresist on the dispersion of quantum dots, so that the quantum dots can be fully dispersed and evenly distributed, thereby ensuring the high resolution of the quantum dot color conversion film; (2) This application achieves high-resolution full-color Micro LED display by dispersing red and green quantum dots on a color conversion film and superimposing a blue light-emitting chip.

[0019] Therefore, the present invention has novel conception, ingenious design, simplified process, greatly improved quantum dot stability, and effectively reduced costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the color conversion film prepared by the present invention; Figure 2 This is a schematic diagram of the structure of the full-color Micro LED display device of the present invention.

[0021] In the figure: color conversion film 1, quantum dots 2, photosensitizer 3, polymer 4, blue light-emitting LED chip 5, filter layer 6, photoresist and graphene film 7, nickel film 8, substrate 9. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. Example

[0023] A preparation method of a mesh quantum dot color conversion film, the specific preparation steps comprising: S1: preparing quantum dot materials emitting red light, organic solvents, and surfactants, adding the organic solvents and surfactants into a reaction container, heating at a constant temperature and stirring to obtain a uniform reaction solution; S2: Injecting quantum dot materials into the reaction container in a certain proportion, keeping a constant temperature during injection, and keeping it for a certain time to allow the reaction to be complete; S3: After the reaction is completed, the mixture is cooled to room temperature to obtain a crude colloidal solution; S4: centrifuging, washing, and dispersing the crude colloidal solution to remove impurities and unreacted substances, thereby obtaining a quantum dot colloidal solution emitting red light; S5: preparing a quantum dot colloidal solution emitting green light in the hot injection method, and then mixing them in a molar ratio of 1:8-1:1; S6: dissolving the lens material polymer polymethyl methacrylate in a chlorobenzene solvent to obtain a polymer solution, then adding the uniformly mixed quantum dot colloid solution to the polymer solution, heating and stirring to obtain a quantum dot polymer solution; S7: adding a small amount of photosensitizer diphenylacetone to the quantum dot polymer solution, heating to 40°C and stirring evenly to obtain a final quantum dot solution, wherein the mass fraction of quantum dots is 1-10%, the mass fraction of lens material polymer polymethyl methacrylate is 85-92%, the mass fraction of crosslinking agent propylene diamine is 0.5-5%, the mass fraction of photosensitizer diphenylacetone is 0.05-1%, and the mass fraction of organic solvent chlorobenzene is 5-10%; S8: The final quantum dot solution was spin-coated on the substrate for 40 seconds, and then irradiated with ultraviolet light for 120 seconds, with a wavelength of 365 nm and an intensity of 10 mW / cm 2 The polymer and the photosensitizer are cross-linked to form a network structure, and the quantum dots are embedded in the network polymer to prepare a network polymer quantum dot film, which can be used as a color conversion film for full-color Micro LEDs, such as Figure 1 shown. Example

[0024] A full-color Micro LED display device is a multi-layer stacked structure, such as Figure 2 As shown, the bottom layer is the substrate, and the substrate is made of materials such as PCB substrate, glass, sapphire, etc.; a blue light-emitting LED chip is arranged on the substrate, and a nickel film is deposited between the blue light-emitting LED chips, which is mainly used to fill the gap matrix generated after the blue light-emitting LED chip is welded to assist the blue light-emitting LED chip in heat dissipation; a layer of photoresist and graphene film are spin-coated on the blue light-emitting LED chip and the nickel film: first, the negative photoresist and graphene are heated and stirred evenly in an organic solvent, wherein the mass fraction of the negative photoresist is 20%-40%, the mass fraction of the graphene is 10-20%, and the mass fraction of the organic solvent is 40-70%, and the mixed solution is spin-coated at a speed of 2000rpm for 10s. After coating, the surface is flat and transparent after baking, and the thickness ranges from 500nm to 2μm; then, a color conversion film is spin-coated on the photoresist and the graphene film. Referring to the spin-coating step in Example 1, the final quantum dot solution is spin-coated on the photoresist and the graphene film at a speed of 3000rpm, and the mask with a pixel size of 5μm*5μm is exposed to ultraviolet light for 120 seconds, and finally developed with a developer to obtain a patterned film; finally, a filter layer is covered on the color conversion film: first, a color resist layer photoresist film of one color is spin-coated, and a mask with a specific pattern is used to expose and develop to form a color resist layer pattern of the color, and the same method is repeated to form color resist layer patterns of the other two colors, and finally a filter layer is formed to complete the preparation of a full-color Micro LED display device.

Claims

1. A method for preparing a network quantum dot color conversion film, characterized in that: The following steps are involved: S1: synthesize quantum dot colloidal solutions emitting red light and green light by hot injection method, and mix them evenly according to the proportion; S2: dissolving the polymer in an organic solvent to obtain a polymer solution, then adding the mixed quantum dot colloid solution to the polymer solution, heating and stirring to obtain a quantum dot polymer solution; S3: Add a small amount of photosensitizer to the quantum dot polymer solution, and heat and stir evenly on a heating plate at 40°C to obtain the final quantum dot solution; S4: The final quantum dot solution was spin-coated on the substrate for 40 seconds, and then irradiated with ultraviolet light for 120 seconds, with a wavelength of 365 nm and an intensity of 10 mW / cm 2 The polymer and the photosensitizer are cross-linked to form a network structure, and the quantum dots are embedded in the network polymer to prepare a network polymer quantum dot film.

2. The preparation method according to claim 1, characterized in that: The raw materials required for the preparation process are, according to the final quantum dot solution, the mass fraction of the quantum dot material is 1-10%, the mass fraction of the polymer is 85-92%, the mass fraction of the photosensitizer is 0.05-1%, and the mass fraction of the organic solvent is 5-10%.

3. The preparation method according to claim 1, characterized in that: The quantum dot material is II-VI quantum dots or III-V quantum dots or perovskite quantum dots, or the single-core nanoparticles of the above materials are coated with one or more layers of coating materials, and the coating material is any one of CdS, ZnO, ZnS, ZnSe, ZnTe or alloy materials or a combination of at least two thereof.

4. The preparation method according to claim 1, characterized in that: The organic solvent is a mixture of one or more of chloroform, toluene, chlorobenzene, alkanes, olefins, aromatic hydrocarbons, alcohols, ethyl acetate, halogenated alkanes, halogenated olefins, halogenated aromatic hydrocarbons, diol derivatives, and ketones.

5. The preparation method according to claim 1, characterized in that: The polymer is one of polycarbonate, polypropylene, polymethyl methacrylate, polysiloxane polymer and polyalkylene oxide polymer.

6. The preparation method according to claim 1, characterized in that: The photosensitizer is one of hydrogen abstraction photosensitizers such as benzophenone and 2,4-dihydroxybenzophenone, or one of cleavage photosensitizers such as 2-hydroxy-2-methyl-1-phenylpropanone and 1-hydroxycyclohexylphenyl ketone, or one of cationic photosensitizers such as diazonium salts and diaryliodonium salts, or a mixture of at least two of the above three categories.

7. A preparation method according to any one of claims 1 to 6, wherein the prepared network polymer quantum dot film is used as a color conversion film for full-color Micro LEDs.

8. A full-color Micro LED display device, characterized in that: Including multi-layer structures: substrate; The blue light-emitting chip is transferred to the substrate through transfer technology; A nickel film, deposited onto the substrate, fills the gap matrix between the blue light-emitting chips; A film of photoresist and graphene is spin-coated on top of the blue light-emitting chip layer; A color conversion film, a network polymer quantum dot film obtained by spin coating the final quantum dot solution; Filter layer.

9. The full-color Micro LED display device according to claim 8, characterized in that: The photoresist and graphene film is obtained by the following steps: heating and stirring the negative photoresist and graphene in an organic solvent, wherein the mass fraction of the negative photoresist is 20%-40%, the mass fraction of the graphene is 10-20%, and the mass fraction of the organic solvent is 40-70%, and the mixed solution is spin-coated on the blue light-emitting chip at a speed of 2000 rpm for 10 seconds. After baking, the surface is flat and transparent, and the thickness ranges from 500 nm to 2 μm. The color conversion film is obtained by the following steps: spin coating the final quantum dot solution on the photoresist and graphene film at a rotation speed of 3000 rpm, exposing the mask with a pixel size of 5 μm*5 μm to ultraviolet light for 120 seconds, and finally developing with a developer to obtain a patterned film; The filter layer is obtained by the following steps: firstly, a color resist layer photoresist film is formed by spin coating, and then a mask with a specific pattern is used for exposure and development to form a color resist layer pattern of the color; then the same method is repeated to form color resist layer patterns of the other two colors, and finally the filter layer is formed.

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