Quantum dot color conversion method and quantum dot color conversion layer structure

Abstract

The invention relates to the technical field of semiconductor display, in particular to a quantum dot color conversion method and a quantum dot color conversion layer structure. The method comprises the steps that retaining walls are prepared on a substrate with a plurality of blue Micro-LEDs, the adjacent blue Micro-LEDs are separated by the retaining walls, and a plurality of corresponding hollow areas are formed; and filling the corresponding hollow areas with a red quantum dot glue solution, a green quantum dot glue solution, a blue quantum dot glue solution and a cyan quantum dot glue solution respectively. According to the application, the original RGB triangular color gamut is expanded into the RGBC quadrilateral color gamut by introducing the cyan-blue quantum dots. The area of the RGBC quadrilateral color gamut is obviously larger than that of a traditional RGB triangular color gamut, and a wider color coverage range is displayed. The RGBC color combination can realize richer color expression, reduce the loss in the color conversion process, and improve the brightness and uniformity of full-color display.

Description

Technical Field

[0001] The present application relates to the field of semiconductor display technology, and in particular to a quantum dot color conversion method and a quantum dot color conversion layer structure. Background Art

[0002] Each pixel in the Micro-LED display contains red, green and blue LED light sources, which can emit light independently and produce high-precision colors.

[0003] Existing full-color display technology mainly uses the color conversion scheme of blue light-excited quantum dots to achieve RGB full-color display. However, the color gamut range of this RGB color combination is limited by blue light leakage, the half-peak width of red and green quantum dots, and the RGB color gamut combination, resulting in a limited overall color gamut area and unsatisfactory display effect.

[0004] In order to enhance the full-color display effect, various improvement methods are usually used, such as increasing the thickness of the quantum dot layer and optimizing the deposition technology of quantum dots, but these methods have problems such as increased manufacturing complexity and rising costs. Some recent studies have achieved significant improvements by using high-concentration quantum dot films, but the color gamut coverage still needs to be improved. Summary of the invention

[0005] This application aims to solve the problem of limited color gamut coverage in existing full-color display technology. By designing an innovative RGBC color combination scheme, the original RGB triangle color gamut is expanded to an RGBC quadrilateral color gamut, the color gamut area is increased, and the full-color display effect is enhanced.

[0006] To achieve the above objectives, the present application provides a quantum dot color conversion method and a quantum dot color conversion layer structure.

[0007] In a first aspect of the present application, the present application provides a quantum dot color conversion method, comprising:

[0008] Preparing a retaining wall on a substrate with a plurality of blue Micro-LEDs, wherein the retaining wall separates adjacent blue Micro-LEDs and forms a corresponding plurality of hollow areas;

[0009] The corresponding hollow areas are filled with red quantum dot glue liquid, green quantum dot glue liquid, blue quantum dot glue liquid and cyan quantum dot glue liquid respectively.

[0010] Furthermore, the step of preparing a retaining wall on a substrate with a plurality of blue Micro-LEDs includes:

[0011] Evenly coating a layer of black photoresist on the surface of the substrate;

[0012] Depositing metal aluminum on the surface of the black photoresist by electron beam evaporation technology;

[0013] Coating a common photoresist on the surface of the metal aluminum, performing photolithography and developing to form an area required for filling quantum dots;

[0014] A plasma etching process is used on the surface of the common photoresist to etch the metal aluminum in the corresponding area;

[0015] Cleaning residual common photoresist on the substrate to form imaged metal aluminum, wherein the imaged metal aluminum covers the surface of the black photoresist;

[0016] A plasma etching process is used on the surface of the black photoresist to etch the black photoresist to form a retaining wall.

[0017] Further, the corresponding hollow areas are filled with red quantum dot glue liquid, green quantum dot glue liquid, blue quantum dot glue liquid and cyan-blue quantum dot glue liquid in the order of upper left, upper right, lower left and lower right.

[0018] Furthermore, the red quantum dot glue liquid, the green quantum dot glue liquid, the blue quantum dot glue liquid and the cyan quantum dot glue liquid are printed into the corresponding hollow areas using inkjet printing technology.

[0019] Furthermore, the material of the quantum dots includes one of the following: Si, CdS, CdSe, InP, PbSe, PbS, ZnS, ZnSe, InAs, GaAs, GaP and perovskite.

[0020] Furthermore, the printing thickness of the four colors of quantum dots, RGBC, is 15μm-20μm.

[0021] Furthermore, it also includes scattering particles filled into the corresponding hollow areas.

[0022] In a second aspect of the present application, the present application further provides a quantum dot color conversion layer structure, comprising:

[0023] A quantum dot color conversion layer structure is obtained by the quantum dot color conversion method as described in the first aspect of the present application.

[0024] Furthermore, the plurality of hollow areas are a plurality of independently arranged RGBC pixel areas or a plurality of multiplexed arranged RGBC pixel areas.

[0025] The beneficial effects of this application are:

[0026] This application expands the original RGB triangular color gamut into an RGBC quadrilateral color gamut by introducing cyan-blue quantum dots. The RGBC quadrilateral color gamut is significantly larger than the traditional RGB triangular color gamut, showing a wider range of color coverage. The RGBC color combination can achieve richer color expression, reduce the loss in the color conversion process, and improve the brightness and uniformity of the full-color display. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of the quantum dot color conversion method of an embodiment of the present application;

[0028] Figure 2 It is a schematic diagram of the retaining wall preparation process of an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of retaining wall preparation according to an embodiment of the present application;

[0030] Figure 4 is a schematic diagram of an RGBC pixel in an embodiment of the present application;

[0031] Figure 5 is the RGBC pixel of the embodiment of the present application in the CIE 1931 chromaticity diagram;

[0032] Figure 6 is a schematic diagram of glue filling in an embodiment of the present application;

[0033] Figure 7 It is a schematic diagram of the quantum dot color structure of an embodiment of the present application. DETAILED DESCRIPTION

[0034] The present application is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that in the description of the present application, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific manner, and therefore cannot be understood as a limitation on the present application. The terms "first", "second", "third", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0035] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0036] At present, the existing full-color display technology mainly uses the color conversion scheme of blue light-excited quantum dots to achieve RGB full-color display. In order to enhance the full-color display effect, various improvement methods are usually adopted, such as increasing the thickness of the quantum dot layer and optimizing the deposition technology of quantum dots, but these methods have problems such as increased manufacturing complexity and rising costs.

[0037] Based on this, the present application hopes to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in the subsequent embodiments.

[0038] See also Figure 1 , Figure 1 : is a flow chart of the quantum dot color conversion method of the embodiment of the present application; the embodiment of the present application provides a quantum dot color conversion method, which specifically includes the following steps:

[0039] S10, preparing a retaining wall on the substrate with a plurality of blue Micro-LEDs, wherein the retaining wall separates adjacent blue Micro-LEDs and forms a plurality of corresponding hollow areas;

[0040] S20, respectively filling the corresponding hollow areas with red quantum dot glue liquid, green quantum dot glue liquid, blue quantum dot glue liquid and cyan-blue quantum dot glue liquid.

[0041] The above-mentioned quantum dot color conversion method prepares a retaining wall on the substrate to divide it into a hollow area and a retaining wall area, and pours a quantum dot solution into the hollow area, so as to prepare a convex and controllable RGBC quantum dot array to achieve better full-color display.

[0042] It should be noted that the substrate in the present application can be a substrate with a transparent surface; a surface that can be used to stack patterned film layers. The thickness of the structure involved in the present application refers to the thickness of the structure in a direction perpendicular to the surface of the substrate.

[0043] Specifically, in step S10, the substrate may be, for example, a sapphire substrate, a glass substrate, an acrylic substrate or a quartz substrate. The blue Micro-LED is densely integrated on a substrate in a matrix form; the preparation of blue Micro-LED involves some epitaxial growth and chip manufacturing processes. In the epitaxial growth stage, by precisely controlling the material growth conditions, a buffer layer, an N-type semiconductor layer, a multi-quantum well light-emitting layer and other structures are grown on the substrate in sequence. Among them, the multi-quantum well light-emitting layer is the key part of light emission, and is composed of a superlattice structure of multiple InGaN multi-quantum well layers and multi-quantum barrier layers. By adjusting the ratio of In and Ga and the number of quantum well layers, the wavelength of the emitted light can be controlled to obtain blue light. Since the formation of multiple blue Micro-LEDs on a substrate is a technology well known to those skilled in the art, this application does not make specific limitations on this.

[0044] In the embodiments of the present application, Figure 2 As shown, the method of preparing a retaining wall on a substrate with a plurality of blue Micro-LEDs includes:

[0045] S101, uniformly coating a layer of black photoresist on the surface of the substrate;

[0046] In some embodiments, this embodiment can evenly coat a layer of black photoresist on the surface of the substrate, heat to 120°C and maintain for 2 minutes. To achieve a higher black barrier thickness, the black photoresist is repeatedly coated and heated 3 times, and finally reaches a suitable thickness of about 15 microns. This multiple coating method can generate a thicker black photoresist, achieve a higher black barrier thickness, block the leakage of light between pixels, reduce the light interference between adjacent pixels, and thus enhance the contrast of the display screen.

[0047] S102, evaporating metal aluminum on the surface of the black photoresist by electron beam evaporation technology;

[0048] In some embodiments, this embodiment can use electron beam evaporation technology to evaporate a 50nm layer of aluminum metal on the uniform black photoresist surface. The metal aluminum film produced by electron beam evaporation technology has high adhesion and density. This helps to ensure a close bond between the metal aluminum and the black photoresist, reducing performance degradation caused by shedding or peeling. At the same time, the dense metal aluminum film can also provide better conductivity and heat dissipation, which helps to improve the stability and life of Micro-LED.

[0049] S103, coating the surface of the metal aluminum with ordinary photoresist, performing photolithography and developing, and forming an area required for filling quantum dots;

[0050] In some embodiments, this embodiment uniformly coats ordinary photoresist on the surface of metal aluminum, performs photolithography and development, and forms the area required for filling quantum dots. A plasma etching process is used to etch the metal aluminum in this area. The ordinary photoresist can be a common photoresist, such as a phenolic resin photoresist. After exposure, the photoresist becomes soluble in a developer in the exposed area, and the unexposed area remains insoluble. It is suitable for the production of high resolution and fine patterns; for example, an epoxy resin photoresist. After exposure, the photoresist is cross-linked and cured in the exposed area, and the unexposed area is soluble in a developer. It is suitable for applications requiring high contrast and high resolution.

[0051] S104, using a plasma etching process on the surface of the common photoresist to etch the metal aluminum in the corresponding area;

[0052] In some embodiments, this embodiment uniformly coats ordinary photoresist on the surface of metal aluminum, performs photolithography and development, and forms a region required for filling quantum dots. A plasma etching process is used to etch the metal aluminum in the region.

[0053] S105, cleaning residual common photoresist on the substrate to form imaged metal aluminum, wherein the imaged metal aluminum covers the surface of the black photoresist;

[0054] In some embodiments, the present embodiment cleans the residual ordinary photoresist to form patterned metal aluminum, which covers the surface of the black photoresist. The black photoresist is etched using a plasma etching process to form pits for quantum dot filling.

[0055] S106, using a plasma etching process on the surface of the black photoresist to etch the black photoresist to form a retaining wall.

[0056] In some embodiments, the residual aluminum and photoresist together form a black barrier wall. Figure 3 As shown, the substrate 100 includes a plurality of blue Micro-LEDs 200 , and the retaining walls 300 separate the adjacent blue Micro-LEDs 200 to protect or block certain pixel areas in subsequent process steps to avoid interference between pixels.

[0057] In the embodiment of the present application, in step S20, if Figure 4 As shown, the present application can use red quantum dot solution, green quantum dot solution, blue quantum dot solution and cyan quantum dot solution to fill the corresponding hollow areas in the order of upper left, upper right, lower left and lower right, thereby forming corresponding RGBC pixel points, and these RGBC pixel areas are arranged independently.

[0058] In some embodiments, the present application can also form multiple RGBC pixel points in the order of upper left, upper right, lower left and lower right, but some pixel points can be reused. These RGBC pixel areas are reused and arranged. For example, the C pixel is reused, and the surrounding RGB pixel points can share one C pixel, which can reduce the layout space.

[0059] The embodiment of the present application introduces cyan quantum dots to expand the original RGB triangular color gamut into an RGBC quadrilateral color gamut, such as Figure 5 As shown. In the CIE 1931 chromaticity diagram, the RGBC quadrilateral color gamut area is significantly larger than the traditional RGB triangular color gamut, and this embodiment shows a wider color coverage. Specifically, the RGBC color combination can achieve richer color expression, reduce the loss in the color conversion process, and improve the brightness and uniformity of the full-color display.

[0060] In some embodiments, this embodiment uses inkjet printing to print red quantum dot glue liquid, green quantum dot glue liquid, blue quantum dot glue liquid and cyan-blue quantum dot glue liquid into the corresponding hollow areas, such as Figure 6 As shown, the substrate 100 includes a plurality of blue Micro-LEDs 200, which are separated by retaining walls 300 to form corresponding hollow areas; the hollow areas are sequentially filled with red quantum dot glue liquid, green quantum dot glue liquid, blue quantum dot glue liquid and cyan-blue quantum dot glue liquid. This method can accurately print the four colors of quantum dot solutions at the pixel position, thereby achieving high-resolution and high-quality display.

[0061] In some embodiments, the material of the quantum dot includes one of the following: Si, CdS, CdSe, InP, PbSe, PbS, ZnS, ZnSe, InAs, GaAs, GaP and perovskite. Those skilled in the art can select the corresponding quantum dot material according to actual needs, and this application does not make specific limitations on this.

[0062] In some embodiments, the depth of the hollow area is 15-20um. Then, when printing the quantum dot material, the printing thickness can correspond to 15-20um, or can be less than 15-20um to ensure that each pixel does not cause interference, and can also be greater than 15-20um to form a raised morphology; at the same time, it is also necessary to ensure that the printing thickness of the four colors is consistent, and the light intensity they emit will be more balanced, reducing the color difference phenomenon, thereby ensuring the accuracy and consistency of the color of the display device.

[0063] In some preferred embodiments of the present application, scattering particles filling the gaps are also included. The role of scattering particles in LEDs is mainly to enhance the scattering and absorption of light. When blue light is irradiated onto the scattering particles, the particles will scatter the light in all directions, thereby increasing the chance of light contacting the quantum dots. In addition, scattering particles can also improve the absorption efficiency of quantum dots for blue light, so that more blue light can be absorbed by quantum dots and converted into red (green) light. Combining scattering particles with quantum dots can further optimize the light-color conversion efficiency of LEDs. The addition of scattering particles not only enhances the scattering and absorption of light, but also makes the distribution of quantum dots in the LED more uniform. This helps to improve the uniformity and color purity of the light emission of the LED. At the same time, scattering particles can also reduce the direct leakage of blue light in the LED, thereby improving the color conversion efficiency.

[0064] Figure 7 is a diagram of the quantum dot color conversion layer structure of an embodiment of the present application, such as Figure 7As shown, it includes a substrate 100, and a plurality of blue Micro-LEDs 200 are arranged above the substrate 100. The plurality of blue Micro-LEDs 200 are separated by retaining walls 300 to form corresponding hollow areas; the hollow areas are filled with red quantum dots, green quantum dots, blue quantum dots and cyan quantum dots with a thickness of 15-20 um.

[0065] The preferred specific embodiments of the present application are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present application without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art based on the concept of the present application through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A quantum dot color conversion method, characterized in that: include: Preparing a retaining wall on a substrate with a plurality of blue Micro-LEDs, wherein the retaining wall separates adjacent blue Micro-LEDs and forms a corresponding plurality of hollow areas; The corresponding hollow areas are filled with red quantum dot glue liquid, green quantum dot glue liquid, blue quantum dot glue liquid and cyan quantum dot glue liquid respectively.

2. The quantum dot color conversion method according to claim 1, characterized in that: The method of preparing a retaining wall on a substrate with a plurality of blue Micro-LEDs comprises: Evenly coating a layer of black photoresist on the surface of the substrate; Depositing metal aluminum on the surface of the black photoresist by electron beam evaporation technology; Coating a common photoresist on the surface of the metal aluminum, performing photolithography and developing to form an area required for filling quantum dots; A plasma etching process is used on the surface of the common photoresist to etch the metal aluminum in the corresponding area; Cleaning residual common photoresist on the substrate to form imaged metal aluminum, wherein the imaged metal aluminum covers the surface of the black photoresist; A plasma etching process is used on the surface of the black photoresist to etch the black photoresist to form a retaining wall.

3. The quantum dot color conversion method according to claim 1, characterized in that: The corresponding hollow areas are filled with red quantum dot glue solution, green quantum dot glue solution, blue quantum dot glue solution and cyan-blue quantum dot glue solution in the order of upper left, upper right, lower left and lower right.

4. The quantum dot color conversion method according to claim 1 or 3, characterized in that: The red quantum dot glue liquid, the green quantum dot glue liquid, the blue quantum dot glue liquid and the cyan-blue quantum dot glue liquid are printed into the corresponding hollow areas using inkjet printing technology.

5. The quantum dot color conversion method according to claim 4, characterized in that: The material of the quantum dot colloid solution includes one of the following: Si, CdS, CdSe, InP, PbSe, PbS, ZnS, ZnSe, InAs, GaAs, GaP and perovskite.

6. The quantum dot color conversion method according to claim 4, characterized in that: The printing thickness of quantum dots in four colors of RGBC is 15μm-20μm.

7. The quantum dot color conversion method according to claim 4, characterized in that: Also included are scattering particles filled into the corresponding hollow regions.

8. A quantum dot color conversion layer structure, characterized in that: A quantum dot color conversion layer structure obtained by the quantum dot color conversion method as described in any one of claims 1 to 7.

9. The quantum dot color conversion layer structure according to claim 8, characterized in that: The plurality of hollow areas are a plurality of independently arranged RGBC pixel areas or a plurality of multiplexed arranged RGBC pixel areas.

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