Color conversion optical filter and preparation method thereof

Abstract

The invention belongs to the technical field of display, and discloses a color conversion optical filter which comprises a transparent substrate, the upper side of the transparent substrate is divided into a plurality of pixel point areas, grooves are formed in the positions, corresponding to the boundaries of the pixel point areas, of the upper surface of the transparent substrate, the grooves are filled with conductive materials, and metal isolation walls are arranged on the upper surfaces of the conductive materials. The metal separating walls are used for surrounding the corresponding pixel point areas, and red, green and blue quantum dots or fluorescent powder materials are placed in the pixel point areas. The color conversion optical filter prepared by the method is high in light emitting efficiency and high in resolution ratio, and has great application prospects in display panels. And meanwhile, the method has the characteristics of low manufacturing cost and high process compatibility, does not need a high-cost mask plate in the photoetching process, and can be suitable for large-size roll-to-roll manufacturing.

Description

Technical Field

[0001] The invention belongs to the field of display technology, and in particular relates to a color conversion filter and a preparation method thereof. Background Art

[0002] The pixel definition layer (bank) structure is used to define the size of display pixels and plays an indispensable role in light-emitting devices or panels. For example, in OLEDs and QLEDs, it can be used as an isolation column to block the overflow of quantum dots or light-emitting material droplets during printing. In the display structure of Micro-LED and quantum dot color conversion layer, it can block the light leakage from the light-emitting device at oblique angles, thereby reducing the color crosstalk problem between light-emitting pixels.

[0003] At present, the bank structure is mainly processed by photolithography. The isolation wall made by photolithography is difficult to achieve a 10μm thickness at a width of 2-3μm. The photosensitive material during photolithography is usually composed of a mixture of photoresist and black particles. Due to the absorption of light by black materials, it is difficult for the light beam to irradiate the inside of the bank film layer, resulting in the inability to completely develop and remove the inside of the high-thickness bank structure, which makes the resolution of the bank structure low, limiting its application in high-resolution display panels. On the other hand, when the bank structure made of black materials is used in a light-emitting device, it has a strong absorption of light, resulting in a decrease in light extraction efficiency.

[0004] In response to the low light extraction efficiency of the bank structure, Shenzhen Huaxing Optoelectronics Semiconductor Display Technology Co., Ltd. has disclosed a patent: Color filter substrate and its preparation method and display panel (Announcement No.: CN114335088A), which evaporates a thin layer of metal material on the surface of the bank structure to improve the reflectivity. Although this method partially solves the problem of low light extraction efficiency, it still does not solve the problem of difficulty in making high-resolution color filter panels, and the production process requires high vacuum deposition equipment, which is costly. Summary of the invention

[0005] In view of this, the present invention proposes a color conversion filter and a preparation method thereof, aiming to solve the problem of difficulty in manufacturing high-resolution color conversion filters and high manufacturing costs.

[0006] To achieve the above-mentioned purpose, the present invention provides a color conversion filter, including a transparent substrate, wherein the upper side of the transparent substrate is divided into a plurality of pixel point areas, grooves are provided at positions corresponding to the boundaries of the pixel point areas on the upper surface of the transparent substrate, the grooves are filled with conductive material, a metal isolation wall is fixedly connected to the upper surface of the conductive material, the metal isolation wall has the same width as the conductive material located in the groove, the metal isolation wall is used to enclose the corresponding pixel point area, and red, green and blue quantum dots or fluorescent materials are placed in the pixel point area.

[0007] Furthermore, the thickness of the conductive material in the groove is 100 nm-3 μm.

[0008] Furthermore, the metal isolation wall has a width of 1 μm-10 μm, a thickness of 5 μm-30 μm, and an aspect ratio (thickness / width) of 1:1-10:1.

[0009] This structural design makes the metal isolation wall have the characteristics of high thickness and narrow width. When printing quantum dot materials in the pixel area, it can effectively confine them in the bank without overflowing and causing color mixing problems.

[0010] Furthermore, the shape of the pixel area on the transparent substrate is one or more combinations of square, circle, ellipse, triangle, pentagon, hexagon, and rhombus.

[0011] Furthermore, the length of the pixel area is 3 μm-200 μm, and the width is 3 μm-200 μm.

[0012] Furthermore, the conductive material is a mixture of one or more of metal nanoparticles, carbon materials, PEDOT:PSS, MXene materials, and metal oxide nanoparticles.

[0013] Furthermore, the material of the metal isolation wall is one or more of copper, silver, gold, chromium, nickel, zinc, and aluminum.

[0014] Such a structural design, in which the metal isolation wall is made of a highly reflective metal material, has a strong reflective effect on light and can greatly improve the light output efficiency when applied to a display panel.

[0015] The present invention also provides a method for preparing a color conversion filter, comprising the following steps:

[0016] S1. Based on the pixel point areas divided on the transparent substrate, a groove is formed at a position corresponding to the boundary of the pixel point area on the upper surface of the transparent substrate;

[0017] S2, filling the groove with a conductive material;

[0018] S3, scraping and coating photoresist on the substrate surface close to the groove;

[0019] S4, forming a second groove facing the conductive material on the photoresist by self-mask photolithography;

[0020] S5, depositing a metal material on the surface of the conductive material to fill the second groove;

[0021] S6, removing the photoresist to form a metal isolation wall and a pixel area surrounded by the metal isolation wall;

[0022] S7. Then, red, green and blue quantum dots or fluorescent luminescent materials are formed in the pixel area to obtain a color conversion filter.

[0023] Furthermore, in step S5, the method of depositing the metal material on the surface of the conductive material is one of electrodeposition, vacuum thermal deposition and magnetron sputtering.

[0024] Furthermore, in step S7, the luminescent material is formed by a printing method or a photolithography method;

[0025] Among them, the printing method is inkjet printing, electrofluidic printing or aerosol printing.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention adopts a chrome-free plate photolithography mask method to achieve the preparation of a high-resolution, high-reflectivity color conversion filter, solving the problem that the traditional black plastic photolithography process is difficult to prepare a high-resolution bank structure and the black plastic bank structure has strong light absorption.

[0028] 2. The high-reflection color conversion filter prepared by the method of the present invention does not require a high-cost photolithography mask, and has a low production cost; it has strong process compatibility and can be applied to large-scale roll-to-roll production; the metal isolation wall has a high thickness and a narrow width, and has a strong reflective effect on light, which can further improve the light output efficiency of the light-emitting device.

[0029] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a cross-sectional view of a color conversion filter of the present invention;

[0031] Figure 2 A flow chart of a method for preparing a color conversion filter according to the present invention;

[0032] Figure 3 A cross-sectional diagram of a process for preparing a color conversion filter according to the present invention;

[0033] Figure 4 A top view of the color conversion filter prepared in Example 1;

[0034] Figure 5 A top view of the color conversion filter prepared in Example 2;

[0035] Figure 6 A top view of the color conversion filter prepared in Example 3;

[0036] The reference numerals in the figure are as follows: transparent substrate 1, conductive material 2, pixel area 3, metal isolation wall 4. DETAILED DESCRIPTION

[0037] In order to make the technical solutions, advantages and purposes of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of this application.

[0038] like Figure 1 As shown, the present invention provides a color conversion filter, including a transparent substrate 1 with a bank structure pattern, the upper side of the transparent substrate 1 is divided into a plurality of pixel areas 3, and the shape of the pixel area 3 on the transparent substrate 1 is a combination of one or more of square, circle, ellipse, triangle, pentagon, hexagon, and rhombus. The length of the pixel area 3 is 3μm-20μm, and the width is 3μm-20μm. Grooves are provided at positions corresponding to the boundaries of the pixel area 3 on the upper surface of the transparent substrate 1, and the grooves are filled with conductive materials 2, and the thickness of the conductive material 2 in the grooves is 100nm-3μm. The conductive material 2 is a mixture of one or more of metal nanoparticles, carbon materials, PEDOT:PSS, MXene materials, and metal oxide nanoparticles. A metal isolation wall 4 is fixedly connected to the upper surface of the conductive material 2, and the width of the metal isolation wall 4 is 1μm-10μm and the thickness is 5μm-30μm. The material of the metal isolation wall 4 is one or more of copper, silver, gold, chromium, nickel, zinc, and aluminum. The metal isolation wall 4 has the same width as the conductive material 2 in the groove, and is used to surround the corresponding pixel area 3, in which red, green and blue quantum dots or phosphor materials are placed.

[0039] like Figure 2 and Figure 3 As shown, the present invention provides a method for preparing a color conversion filter, comprising the following steps:

[0040] S1, based on the pixel area 3 divided on the transparent substrate 1, a groove is formed on the upper surface of the transparent substrate 1 at a position corresponding to the boundary of the pixel area 3;

[0041] S2, filling the groove with conductive material 2;

[0042] S3, scraping and coating photoresist on the substrate surface close to the groove;

[0043] S4, forming a second groove facing the conductive material 2 on the photoresist by self-mask photolithography;

[0044] S5, depositing metal material on the surface of the conductive material 2 to fill the second groove;

[0045] The method of depositing the metal material on the surface of the conductive material 2 is one of electrodeposition, vacuum thermal deposition and magnetron sputtering;

[0046] S6, removing the photoresist to form a metal isolation wall 4 and a pixel area 3 surrounded by the metal isolation wall 4;

[0047] S7, forming red, green and blue quantum dots or phosphor luminescent materials in the pixel area 3, thereby producing a color conversion filter;

[0048] The luminescent material is formed by a printing method or a photolithography method;

[0049] Among them, the printing method is inkjet printing, electrofluidic printing or aerosol printing.

[0050] Example 1

[0051] First, a groove structure with a bank structure pattern is formed on the surface of the PET substrate by nanoimprinting technology. In this embodiment, the groove has a depth of 2μm and a line width of 2μm. The bank structure is square in shape, and the distance between the groove line widths is 5μm (i.e., the side length of the square is 5μm); then, the silver nanoparticle layer is filled in the groove by scraping, and annealed in an oven at 130°C for 10 minutes to make the silver nanoparticles conductive; then, photoresist is scraped on the surface of the substrate, and the thickness of the photoresist is 10μm. Then, photolithography is performed by self-masking to form a second groove with a line width of 2μm and a depth of 10μm on the surface of the conductive silver nanoparticles. Then, metal copper is deposited on the surface of the conductive silver nanoparticle layer by electrodeposition and the second groove is filled. Then, the photoresist is removed, and a copper isolation wall is formed at this time. The copper isolation wall has a thickness of 10μm and a width of 2μm. The length and width of the pixel area surrounded by the copper isolation wall are both 5μm. Finally, red, green and blue quantum dot materials are printed in different pixel regions by electro-fluid printing to form a color conversion filter. The color conversion filter prepared in this embodiment is as follows: Figure 4 shown.

[0052] Example 2

[0053] This embodiment also provides a method for preparing a color conversion filter. The difference from the first embodiment is that in this embodiment, the shape of the pixel point area is circular. The remaining steps of this embodiment are the same as those of the first embodiment. The color conversion filter prepared in this embodiment is as follows: Figure 5 shown.

[0054] Example 3

[0055] This embodiment also provides a method for preparing a color conversion filter. The difference from Embodiment 1 is that in this embodiment, the pixel region has a variety of shapes, including a circle and a rounded rectangle of different sizes. The remaining steps of this embodiment are the same as those of Embodiment 1. The color conversion filter prepared in this embodiment is as follows: Figure 6 shown.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the protection scope of the present invention.

Claims

1. A color conversion filter, characterized in that: It includes a transparent substrate, the upper side of which is divided into a plurality of pixel point areas, grooves are provided on the upper surface of the transparent substrate at positions corresponding to the boundaries of the pixel point areas, the grooves are filled with conductive material, a metal isolation wall is fixedly connected to the upper surface of the conductive material, the metal isolation wall has the same width as the conductive material in the groove, the metal isolation wall is used to enclose the corresponding pixel point area, and red, green and blue quantum dots or fluorescent materials are placed in the pixel point area.

2. A color conversion filter according to claim 1, characterized in that: The thickness of the conductive material in the groove is 100 nm-3 μm.

3. A color conversion filter according to claim 2, characterized in that: The metal isolation wall has a width of 1 μm-10 μm, a thickness of 5 μm-30 μm, and a depth-to-width ratio of 1:1-10:

1.

4. A color conversion filter according to claim 3, characterized in that: The shape of the pixel area on the transparent substrate is one or more combinations of square, circle, ellipse, triangle, pentagon, hexagon and rhombus.

5. The color conversion filter according to claim 1, characterized in that: The length of the pixel area is 3 μm-200 μm, and the width is 3 μm-200 μm.

6. The color conversion filter according to claim 1, characterized in that: The conductive material is a mixture of one or more of metal nanoparticles, carbon materials, PEDOT:PSS, MXene materials, and metal oxide nanoparticles.

7. The color conversion filter according to claim 1, characterized in that: The material of the metal isolation wall is one or more of copper, silver, gold, chromium, nickel, zinc and aluminum.

8. A method for preparing a color conversion filter according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Based on the pixel point areas divided on the transparent substrate, a groove is formed at a position corresponding to the boundary of the pixel point area on the upper surface of the transparent substrate; S2, filling the groove with a conductive material; S3, scraping and coating photoresist on the substrate surface close to the groove; S4, forming a second groove facing the conductive material on the photoresist by self-mask photolithography; S5, depositing a metal material on the surface of the conductive material to fill the second groove; S6, removing the photoresist to form a metal isolation wall and a pixel area surrounded by the metal isolation wall; S7. Then, red, green and blue quantum dots or fluorescent luminescent materials are formed in the pixel area to obtain a color conversion filter.

9. The method for preparing a color conversion filter according to claim 8, characterized in that: In the step S5, the metal material is deposited on the surface of the conductive material by one of electrodeposition, vacuum thermal deposition and magnetron sputtering.

10. The method for preparing a color conversion filter according to claim 8, characterized in that: In the step S7, the luminescent material is formed by a printing method or a photolithography method; Among them, the printing method is inkjet printing, electrofluidic printing or aerosol printing.

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