A method for preparing a light-emitting layer of a large-size display backlight based on two-dimensional nanosheets

Abstract

The present invention discloses a method for preparing a large-size display backlight light-emitting layer based on two-dimensional nanosheets. The backlight light-emitting layer uses group II-VI colloidal semiconductor nanosheets as the red, green, and blue primary color light-emitting pixel units. Each light-emitting color has the narrow-band emission characteristic of nanosheets (<10 nm). The three primary color light-emitting pixel units are gradually prepared by combining a strip-shaped mask plate with a spraying-ultraviolet (UV) curing method. The pixel size of each color light-emitting unit and the size of the display backlight light-emitting layer can be controlled by the structural characteristics of the mask plate. At the same time, the nanosheets are mixed with the UV-curing resin; and the integration and rapid preparation-encapsulation of the display backlight light-emitting layer are realized by combining UV irradiation for rapid curing. The present invention broadens the commercial preparation approach of colloidal semiconductor nanoluminescent materials with excellent optical properties in the display field, and further lays a technical foundation for realizing the controllable, batch, and low-cost preparation of large-size wide-color gamut display backlights based on colloidal semiconductor luminescent materials.

Description

Technical Field

[0001] The present invention relates to a method for preparing a light-emitting layer of a large-size display backlight source based on two-dimensional nanosheets, belonging to the technical field of nanolayer preparation. Background Art

[0002] Since 2015, colloidal semiconductor quantum dots have been successfully commercialized in TV products based on quantum dot LED backlight modules due to their excellent optical properties such as tunable emission wavelength and narrow emission bandwidth (~20 - 40 nm). Due to the wide color gamut, high color purity, and low power consumption display performance of this TV product, it has attracted people's attention. Currently, international brands such as Nanosys and Samsung, as well as many domestic enterprises such as Huawei, Xiaomi, and TCL, have all invested in the construction of quantum dot TV production lines and their products have been on the market for sale. In quantum dot TV products, the display backlight source generally generates white light by a blue LED exciting red and green quantum dot light-emitting films coated thereon. The narrower the emission peak, the more realistic the color reproduction, thus better improving the color gamut of liquid crystal displays. The pursuit of high color purity and wide color gamut display performance has become the development trend of TV display backlight sources. The emission peak bandwidth of traditional quantum dots can usually only be narrowed to 20 nm, making it difficult to further improve the color gamut display performance of products. In recent years, due to their unique one-dimensional quantum confinement effect, colloidal semiconductor nanosheets have excellent optical properties such as narrow emission bandwidth (~10 nm), high fluorescence quantum yield (up to 90%), and tunable emission wavelength with thickness, showing the potential for commercial applications to replace quantum dots to achieve a new generation of high-performance ultra-wide color gamut display backlight sources.

[0003] Currently, this kind of colloidal semiconductor display backlight source generally adopts white LED or hybrid light-emitting layer preparation schemes, which are difficult to meet the requirements of high pixel display performance of future display devices, and are also subject to the traction of multiple factors such as the demand for large-size high pixel display backlight source light-emitting layers, the need to explore colloidal solution preparation processes, and the pursuit of ultra-wide color gamut display performance. Therefore, in order to overcome the bottleneck of the technology for preparing the light-emitting layer of colloidal semiconductor display backlight sources in the colloidal solution process, it is urgently necessary to find an efficient integrated preparation-packaging process to achieve the controllability, batch production, and low-cost preparation of large-size colloidal semiconductor high-definition pixel display backlight source light-emitting layers. Summary of the Invention

[0004] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a method for preparing a light-emitting layer of a large-size display backlight source based on two-dimensional nanosheets, thereby solving the above technical problems.

[0005] To achieve the above object, the technical solution adopted by the present invention is: A method for preparing a light-emitting layer of a large-size display backlight source based on two-dimensional nanosheets, comprising the following steps:

[0006] Step S1: Preparation of the nanosheet-photocurable resin mixed solution with three emission colors of red, green, and blue. The semiconductor nanosheet materials with three emission colors of red, green, and blue are respectively prepared by the colloid chemistry method. First, the surface of the nanosheets is modified with polymer ligands to make them have good dispersion compatibility with the polymer photocuring system. A liquid medium with UV photocuring properties containing copolymer, monomer, and photoinitiator is mixed evenly, and then it is respectively mixed evenly with the nanosheet materials to obtain the nanosheet-photocurable resin mixed solutions with three emission colors of red, green, and blue.

[0007] Step S2: Preparation of the red-emission nanosheet pixel unit. The mask plate is aligned with the light guide plate by using a precision displacement stage. Among them, the width of the hollowed-out area in the mask plate is L1, and the width of the non-hollowed-out area is L2. Then, the nanosheet-photocurable resin mixed solution with red emission is sprayed to obtain the red-emission nanosheet pixel unit.

[0008] Step S3: Formation of the periodic red-nanosheet light-emitting unit. The UV curing light is irradiated on the sprayed nanosheet light-emitting unit, and the liquid film will rapidly transform from the liquid state to the solid state film, thereby forming the periodic red-nanosheet light-emitting unit.

[0009] Step S4: Use the precision displacement stage to vertically move the mask plate relative to the red-nanosheet light-emitting unit in the light guide plate obtained in the above step by a distance of L1, so that the hollowed-out area of the mask plate is adjacent to the red-nanosheet light-emitting unit, exposing the unsprayed area in the light guide plate.

[0010] Step S5: Repeat the above Step S2, Step S3, and Step S4 to successively prepare the green-nanosheet light-emitting unit and the blue-nanosheet light-emitting unit. By horizontally translating the mask plate and repeating Step S2, Step S3, and Step S4 again, finally, the periodically and closely arranged red, green, and blue-nanosheet light-emitting pixel units can be obtained on the entire light guide plate, that is, the pixelated nanosheet display backlight emission layer.

[0011] Furthermore, the red, green, and blue primary color light-emitting pixel units are based on group II-VI colloidal semiconductor nanosheets, and their narrowband emission characteristics (<10 nm).

[0012] By adopting the above technical solution, using group II-VI colloidal semiconductor nanosheets as the red, green, and blue primary color light-emitting pixel units, the nanosheets with narrowband emission characteristics (<10 nm) are beneficial to realizing the ultra-wide color gamut display performance of the device.

[0013] Further, in step S1, the semiconductor nanosheet material is a semiconductor CdSe / CdS core-shell nanosheet, and the red, green, and blue emission colors are regulated by changing the nanosheet thickness; the polymer ligand is polymethyl methacrylate; the copolymer is polyurethane acrylate, the monomer is vinyl acetate, and the photoinitiator is phenylethanone peracid ester, and the volume ratio of the three is 50:45:5.

[0014] Further, in step S2, the ratio of the width L1 of the hollowed-out area to the width L2 of the non-hollowed-out area in the mask is 1:2, and the size of the light-emitting pixel unit depends on the pattern structure size of the mask; the relative spatial positions of the mask and the light guide plate are moved by a precision displacement platform to sequentially spray the red, green, and blue light nanosheet light-emitting pixel units, and a periodically and closely arranged nanosheet display backlight light-emitting layer is obtained on the light guide plate; a mask with a corresponding size is selected for the large-size nanosheet display backlight light-emitting layer.

[0015] Further, under UV curing light irradiation, the sprayed nanosheet light-emitting unit will be rapidly converted from a liquid film to a solid film, directly forming a polymer-encapsulated nanosheet light-emitting pixel unit, greatly simplifying the encapsulation process of the colloidal semiconductor light-emitting layer, and being beneficial to promoting the integrated batch high-efficiency preparation and encapsulation of the nanosheet display backlight light-emitting layer on the enterprise production line.

[0016] The beneficial effects of the present invention are as follows: The present invention proposes a method for preparing a large-size display backlight light-emitting layer based on colloidal semiconductor nanosheets. While improving the optical stability performance of the light-emitting material, the preparation technical solution also greatly simplifies the preparation and encapsulation processes of the colloidal semiconductor light-emitting layer, and thus is beneficial to promoting the commercial application of the integrated batch preparation and encapsulation process of the nanosheet display backlight light-emitting layer. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the mask structure and the structure of the three-primary-color light-emitting layer prepared in the first embodiment of the present invention;

[0018] Figure 2 It is a schematic diagram of the specific preparation steps of the colloidal semiconductor nanosheet display backlight light-emitting layer in the first embodiment of the present invention. In the figure, 1 - nanosheet; 2 - nanosheet-photocurable resin mixed solution; 3 - polymer surface-modified nanosheet; 4 - sequential preparation process of red, green, and blue three-primary-color light-emitting pixel units;

[0019] Figure 3 It is a schematic diagram of the cross-section and surface effect of the colloidal semiconductor nanosheet display backlight light-emitting layer in the first embodiment of the present invention.

[0020] In the figure: 1, nanosheet; 2, nanosheet-photocurable resin mixed solution; 3, polymer surface-modified nanosheet; 4, sequential preparation process of red, green, and blue three-primary-color light-emitting pixel units. Detailed implementation manners

[0021] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0022] Unless otherwise defined, all technical terms and scientific terms used herein have the same meanings as those commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] Technical problem: Due to the characteristics of colloidal semiconductor materials such as traditional surface effects and solution dispersion, in the actual application process in the display field, there are problems such as the lack of high-quality large-size light-emitting layer preparation processes, low efficiency, and poor optical performance stability. The present invention proposes a method for preparing a large-size display backlight light-emitting layer based on colloidal semiconductor nanosheets. While improving the optical stability of the light-emitting material, this preparation technical solution also greatly simplifies the preparation and encapsulation processes of the colloidal semiconductor light-emitting layer, and thus is conducive to promoting the commercial application of the integrated batch preparation and encapsulation processes of the nanosheet display backlight light-emitting layer.

[0024] Example 1:

[0025] The specific preparation steps of a large-size display backlight light-emitting layer based on two-dimensional nanosheets are as follows:

[0026] 1) Use the colloidal chemistry method to prepare CdSe / CdS core-shell nanosheets with three emission colors of red, green, and blue respectively, as shown in Figure 1; first, use polymethyl methacrylate to modify the surface of the nanosheets to improve their good dispersion compatibility with the polymer photocurable resin; mix the liquid medium with UV photocuring properties containing copolymer: polyurethane acrylate, monomer: vinyl acetate, and photoinitiator: acetophenone peracid ester evenly according to the volume ratio of 50:45:5, and then mix it evenly with the nanosheet materials of different emission colors respectively to obtain nanosheet-photocurable resin mixed solutions 2 with three emission colors of red, green, and blue, and form nanosheet materials 3 tightly coated by the polymer system; Figure 2 2) Use a precision displacement stage to overlap the mask plate with the light guide plate. Among them, the ratio of the width L1 of the hollowed-out area in the mask plate to the width L2 of the non-hollowed-out area is 1:2, as shown in

[0027] Figure 1 Figure 1As shown; the size of the light-emitting pixel unit depends on the size of the mask pattern structure. For the large-size nanosheet display backlight emission layer, selecting a mask with a corresponding size can meet the preparation requirements; then spraying a mixed solution of red-light-emitting nanosheets and photocurable resin to obtain a red-light-emitting nanosheet pixel unit, as Figure 2 shown in 4;

[0028] 3) Irradiate the sprayed nanosheet light-emitting unit with UV curing light, and the liquid film will be quickly converted into a solid film, thus forming a periodic red-light nanosheet light-emitting unit, and the remaining areas are blank areas without spraying;

[0029] 4) Use a precision displacement stage to vertically move the mask relative to the red-light nanosheet light-emitting unit in the light guide plate obtained in the above step by a distance L1, so that the hollowed-out area of the mask is closely adjacent to the already sprayed red-light nanosheet light-emitting unit, exposing the unsprayed area;

[0030] 5) Repeat the above steps 2), 3) and 4), and the green-light nanosheet light-emitting unit and the blue-light nanosheet light-emitting pixel unit can be prepared in sequence; by horizontally translating the mask and repeating the above steps 2), 3) and 4) again, finally, periodically and closely arranged red, green and blue light nanosheet light-emitting pixel units can be obtained on the entire light guide plate, as Figure 3 shown; that is, the pixelated nanosheet display backlight emission layer.

[0031] The present invention proposes to use CdSe / CdS core-shell nanosheets with different thicknesses as red, green and blue light-emitting materials, and use polymer ligands to modify the surface of the nanosheets to make them have good dispersion compatibility with the polymer photocurable resin, while improving the optical performance stability of the nanosheets; then, by regulating the mask, the sizes of the three-primary-color nanosheet light-emitting pixel units are accurately controlled, and combined with UV curing to quickly encapsulate the nanosheet light-emitting pixel units, realizing the integrated preparation and encapsulation of the nanosheet display backlight emission layer.

[0032] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a light-emitting layer of a large-size display backlight based on two-dimensional nanosheets, characterized in that, It includes the following steps: Step S1: Preparation of a nanosheet-photocurable resin mixed solution with three light-emitting colors of red, green, and blue. Semiconductor nanosheet materials with three light-emitting colors of red, green, and blue are prepared by colloid chemistry method. First, the nanosheets are surface-modified with polymer ligands to make them have good dispersion compatibility with the polymer photocuring system. A liquid medium with UV photocuring properties containing copolymer, monomer, and photoinitiator is mixed evenly, and then it is mixed evenly with the nanosheet materials respectively to obtain nanosheet-photocurable resin mixed solutions with three light-emitting colors of red, green, and blue. Step S2: Preparation of a red-light-emitting nanosheet pixel unit. The mask plate is overlapped with the light guide plate by using a precision displacement stage. Among them, the width of the hollowed-out area in the mask plate is L1, and the width of the non-hollowed-out area is L2. Then, the nanosheet-photocurable resin mixed solution emitting red light is sprayed to obtain a red-light-emitting nanosheet pixel unit. Step S3: Formation of a periodic red-light nanosheet light-emitting unit. The UV curing light is irradiated on the sprayed nanosheet light-emitting unit, and the liquid film will be quickly transformed from a liquid state to a solid film, thus forming a periodic red-light nanosheet light-emitting unit. Step S4: Use the precision displacement stage to vertically move the mask plate relative to the red-light nanosheet light-emitting unit in the light guide plate obtained in the above step by a distance of L1, so that the hollowed-out area of the mask plate is adjacent to the red-light nanosheet light-emitting unit, exposing the unsprayed area in the light guide plate. Step S5: Repeat the above steps S2, S3, and S4 to sequentially prepare a green-light nanosheet light-emitting unit and a blue-light nanosheet light-emitting unit. By horizontally translating the mask plate and repeating steps S2, S3, and S4 again, finally, a periodically and closely arranged red, green, and blue light nanosheet light-emitting pixel unit, that is, a pixelated nanosheet display backlight light-emitting layer, can be obtained on the entire light guide plate.

2. The method for preparing a large-size display backlight light-emitting layer based on two-dimensional nanosheets according to claim 1, wherein, The red, green, and blue primary color light-emitting pixel units are based on group II-VI colloidal semiconductor nanosheets, and their narrow-band emission characteristics (<10nm).

3. A method for preparing a large-size display backlight light-emitting layer based on two-dimensional nanosheets according to claim 1, characterized in that, In the above step S1, the semiconductor nanosheet material is a semiconductor CdSe / CdS core-shell nanosheet, and the red, green, and blue light-emitting colors are regulated by changing the nanosheet thickness; the polymer ligand is polymethyl methacrylate; the copolymer is polyurethane acrylate, the monomer is vinyl acetate, and the photoinitiator is phenylacetone peracid ester, and the volume ratio of the three is 50:45:

5.

4. The method for preparing a light-emitting layer of a large-size display backlight based on two-dimensional nanosheets according to claim 1, wherein, In the above step S2, the ratio of the width L1 of the hollowed-out area in the mask plate to the width L2 of the non-hollowed-out area is 1:2, and the size of the light-emitting pixel unit depends on the pattern structure size of the mask plate; by moving the relative spatial position of the mask plate and the light guide plate through the precision displacement platform, the red, green, and blue light nanosheet light-emitting pixel units are sprayed sequentially, and a periodically and closely arranged nanosheet display backlight light-emitting layer is obtained on the light guide plate; a mask plate with a corresponding size is selected for the large-size nanosheet display backlight light-emitting layer.

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