A method for preparing a color conversion layer of a full-color device based on electrophoretic deposition of quantum dots

Abstract

The application discloses a method for preparing a color conversion layer of a full-color device based on electrophoretic deposition of quantum dots, and forms a transparent electrode layer on a transparent substrate, wherein the transparent electrode comprises an electrode total strip and a plurality of electrode finger strips arranged at intervals, and the end of the electrode finger strip is connected with the electrode total strip; a patterned insulating layer is formed on the transparent electrode layer to form separated quantum dot deposition areas on the electrode finger strips, a light-proof conductive metal layer is formed between the quantum dot deposition areas, and then charged quantum dots are selectively deposited in the quantum dot deposition areas through an electrophoretic process. The application can realize uniform and selective deposition of quantum dots in a large area quickly, and can avoid surface residues by connecting and adsorbing quantum dots with opposite electric properties to a preset patterned array area, so that the quantum dot pattern is controllable, the reliability is high, and the display performance is better.

Description

Technical Field

[0001] This invention belongs to the field of display technology, specifically relating to a method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots. Background Technology

[0002] Micro-LED technology is based on traditional inorganic III-IV semiconductors. It has high brightness and good stability, making it more suitable for manufacturing high-brightness microdisplays. Currently, in the field of full-color display applications, it is difficult to grow red, green and blue emitting Micro-LED chips on the same epitaxial layer. Therefore, to achieve full-color display, mass transfer is often used. However, improving the yield of mass transfer technology has stringent requirements, and the different turn-on voltages of Micro-LEDs of different colors make the design of the driving circuit more complex. There are many challenges in the large-scale mass production of high-pixel-density full-color Micro-LED microdisplays.

[0003] In the quantum dot-based full-color display technology roadmap, the efficient and precise deposition of quantum dot materials into the corresponding locations is crucial. Currently, commonly used methods in industry, such as inkjet printing and photolithography, cannot meet the industry's requirements.

[0004] Electrophoretic deposition of quantum dot patterns offers advantages such as simple equipment and high repeatability. The independence of quantum dot sub-pixel regions determines the effectiveness of photoluminescence color conversion. Controlling the thickness of the quantum dot pattern by orders of magnitude for different wavelength excitation sources affects color conversion efficiency. In current literature on electrophoretic deposition of quantum dot patterns, while masking techniques can achieve deposition of quantum dot materials at designated locations on the device, their application in full-color displays faces the challenge of high cost, hindering large-scale device production. Furthermore, quantum dot patterns cannot be arrayed. Electrical connectivity issues during electrophoretic deposition prevent each sub-pixel from being truly independent, resulting in interconnected luminescent areas between sub-pixels after photoluminescence, significantly impacting the display pattern's appearance. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for fabricating a color conversion layer for full-color devices based on electrophoretic deposition of quantum dots. It employs electrophoresis technology combined with semiconductor process technologies such as photolithography, etching, and insulating thin film deposition to achieve a simple, feasible, and inexpensive method for fabricating high-quality Micro-LED full-color display devices based on electrophoretic deposition technology.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for fabricating a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots includes the following steps:

[0008] 1) A transparent electrode layer is formed on a transparent substrate. The transparent electrode layer includes at least one transparent electrode. The transparent electrode includes an electrode strip and a plurality of electrode fingers arranged at intervals. The ends of the electrode fingers are connected to the electrode strip.

[0009] 2) An insulating layer is deposited on the transparent electrode layer, the insulating layer is patterned, and several openings are formed on each electrode finger strip as quantum dot deposition areas, and openings on the electrode strip are formed as electrical contact areas.

[0010] 3) Deposit an opaque conductive metal layer on the insulating layer, and pattern the opaque conductive metal layer to correspond to the openings of the quantum dot deposition area and the electrical contact area;

[0011] 4) Connect one of the positive and negative electrodes of the electrophoresis apparatus to the electrical contact area and the other to the opaque conductive metal layer. Place the apparatus in an electrophoresis pool containing a quantum dot solution, wherein the surface charge of the quantum dots is opposite to that of the electrode contact area. Turn on the circuit to allow the quantum dots to be deposited in the quantum dot deposition area, forming a quantum dot sub-pixel unit.

[0012] Optionally, the electrophoresis device uses a DC electric field voltage of 3~15V and a current of 10~30A.

[0013] Optionally, the transparent electrode layer is made of ITO and has a thickness of 50-100 nm; the insulating layer has a thickness of 100-300 nm.

[0014] Optionally, the transparent electrode layer includes a first transparent electrode and a second transparent electrode that do not contact each other, with the electrode fingers of the first transparent electrode and the second transparent electrode arranged alternately.

[0015] Optionally, in step 4), the first quantum dot and the second quantum dot are deposited respectively.

[0016] When depositing the first quantum dot, one of the positive and negative electrodes of the electrophoresis apparatus is connected to the electrical contact area of ​​the first transparent electrode, and the other is connected to the electrical contact area of ​​the opaque conductive metal layer and the second transparent electrode. The apparatus is placed in an electrophoresis pool containing the first quantum dot solution, and the circuit is turned on to allow the quantum dots to be deposited in the quantum dot deposition area of ​​the first transparent electrode. After deposition, the apparatus is solidified.

[0017] When depositing the second quantum dot, one of the positive and negative electrodes of the electrophoresis apparatus is connected to the electrical contact area of ​​the second transparent electrode, and the other is connected to the electrical contact area between the opaque conductive metal layer and the first transparent electrode. The apparatus is then placed in an electrophoresis pool containing the second quantum dot solution. The circuit is turned on so that the quantum dots are deposited in the quantum dot deposition area of ​​the second transparent electrode. After deposition, the particles are cured.

[0018] Optionally, the first quantum dot and the second quantum dot are red quantum dots and green quantum dots, and a blue light transmission area is reserved in the array of alternating electrode fingers of the first transparent electrode and the second transparent electrode. In steps 2) and 3), when the insulating layer and the opaque conductive metal layer are patterned, openings are simultaneously formed in the blue light transmission area.

[0019] Optionally, before step 3), steps 1) and 2) are repeated to form a multilayer structure in which transparent electrode layers and insulating layers are alternately stacked, wherein the transparent electrode layers do not contact each other, and the projections of the electrode fingers and electrode strips of different transparent electrode layers on the transparent substrate do not overlap.

[0020] Optionally, it includes two transparent electrode layers, wherein the first transparent electrode layer includes a first transparent electrode and a second transparent electrode that are not in contact with each other, and the second transparent electrode layer includes a third transparent electrode, and the electrode fingers of the first transparent electrode, the second transparent electrode and the third transparent electrode are alternately arranged on the transparent substrate.

[0021] Optionally, red quantum dots, green quantum dots, and blue quantum dots are deposited in the quantum dot deposition regions of the first transparent electrode, the second transparent electrode, and the third transparent electrode, respectively.

[0022] A method for fabricating a full-color device, comprising the following steps:

[0023] 1) Provide a Micro-LED light-emitting chip, wherein the Micro-LED light-emitting chip has a plurality of light-emitting units;

[0024] 2) The color conversion layer is prepared using the above-mentioned method for preparing a full-color device color conversion layer based on electrophoretic deposition of quantum dots;

[0025] 3) The transparent substrate of the color conversion layer is bonded to the Micro-LED light-emitting chip, wherein the quantum dot sub-pixel unit corresponds one-to-one with the light-emitting unit.

[0026] Among them, red, green, and blue quantum dot materials (material selection A) X Q Y M ZThe series consists of elements A, which are one or two combinations of Ba, Ag, Na, Fe, In, Cd, Zn, Ga, Mg, Pb, and Cs, with X ranging from 0.5 to 1.5; elements Q, which are C, Cl, O, As, N, P, Se, Te, Ti, Zr, and Pb, with Y ranging from 0.8 to 2; elements M, which are S, As, Se, O, Cl, Br, and I, with Z ranging from 0.5 to 3.5. The main materials selected are CdSe, CsPbBr3, CsPbI3, and ZnS. The diameter of red quantum dot materials is 8-10 nm, and the diameter of green quantum dot materials is 3-7 nm. The blue quantum dot material (with a diameter of 4-6 nm) is mixed with an organic salt containing ionic bonds (any one or at least two combinations of fatty acid salts, sulfate salts, phosphate salts, fatty amine salts, ethanolamine salts, or polyvinyl polyammonium salts) at 90-150℃ to modify the surface of the quantum dot material, making the red and green quantum dot solutions negatively charged. The concentration of red quantum dots is 0.15-0.5 mol / L, the concentration of green quantum dots is 0.2-0.7 mol / L, and the concentration of blue quantum dots is 0.3-0.5 mol / L.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) Electrophoresis technology integrates quantum dots into the array transparent electrode pattern area to achieve rapid and large-area uniform selective deposition of quantum dots. The thickness of the quantum dot pattern film can be controlled by the combination of electric field and quantum dot solution concentration to achieve a wide range of precise control from a few nanometers to tens of micrometers, so as to meet the requirements of different excitation light sources for quantum dot thickness, improve photoluminescence conversion efficiency, low manufacturing cost and high raw material utilization rate. It is not only suitable for rigid substrate deposition, but also applicable to flexible substrates and different complex display structure surfaces.

[0029] (2) By combining photolithography and patterning techniques, a patterned region for quantum dots to be deposited was prepared on the surface of the device. The bottom electrode of each sub-pixel region was separated by a patterned insulating layer. Each sub-pixel in the region to be deposited was independent of each other. During the electrophoretic deposition of quantum dots, different quantum dots were deposited on the device. There were no quantum dots left between each sub-pixel. Combined with Micro-LED chips, full-color display was achieved. The transparent electrode adsorbed oppositely charged quantum dots and deposited them into the preset patterned array region. The surface morphology, packing density, and refractive index of the quantum dot pattern were controllable, achieving high-efficiency color conversion, high pixel density, electric field control of pixel uniformity, less damage to quantum dot materials, high reliability, and better display performance.

[0030] (3) A non-transparent conductive metal layer is deposited on the surface. On the one hand, quantum dot deposition is achieved by electrode control. The non-transparent conductive layer has the same charge polarity as the quantum dots, which can repel quantum dot solutions of the same polarity, so that the quantum dot solution does not remain on the surface. On the other hand, the metal layer is made of non-transparent material, which can reduce light crosstalk between sub-pixels and improve light quality. This technology is simple to operate, has low process difficulty, and does not require the preparation of a mask, so it is inexpensive and conducive to the realization of large-scale industrial production. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the fabrication process of a Micro-LED light-emitting chip.

[0032] Figure 2 This is a schematic diagram of the transparent electrode layer structure during the color conversion layer preparation process in Example 1;

[0033] Figure 3 This is a schematic diagram of the insulating layer deposition and pore structure during the color conversion layer preparation process in Example 1;

[0034] Figure 4 This is a top view schematic diagram of the deposition of an opaque conductive metal layer and the opening structure during the color conversion layer preparation process in Example 1.

[0035] Figure 5 for Figure 4 Cross-sectional view along the a-a' direction;

[0036] Figure 6 This is a schematic diagram of the red quantum dot deposition electrophoresis apparatus used in the color conversion layer preparation process of Example 1.

[0037] Figure 7 This is a schematic diagram of the red quantum dot deposition in the color conversion layer of Example 1;

[0038] Figure 8 This is a schematic diagram of the green quantum dot deposition electrophoresis apparatus used in the color conversion layer preparation process of Example 1;

[0039] Figure 9 and Figure 10 These are top and side view schematic diagrams of the quantum dot color conversion layer in Example 1;

[0040] Figure 11 This is a schematic diagram of the full-color Micro-LED quantum dot color conversion layer in Example 1;

[0041] Figure 12 This is a schematic diagram of the third transparent electrode structure during the color conversion layer preparation process in Example 2;

[0042] Figure 13This is a schematic diagram of the deposition and opening structure of the second insulating layer during the color conversion layer preparation process in Example 2;

[0043] Figure 14 This is a top view schematic diagram of the deposition of an opaque conductive metal layer and the opening structure during the color conversion layer preparation process in Example 2.

[0044] Figure 15 for Figure 14 A schematic diagram of the cross-sectional structure along the a-a' direction;

[0045] Figure 16 This is a schematic diagram of the red quantum dot deposition electrophoresis apparatus used in the color conversion layer preparation process of Example 2;

[0046] Figure 17 This is a schematic diagram of the cross-sectional structure of the quantum dot color conversion layer in Example 2 (same as above). Figure 15 (direction). Detailed Implementation

[0047] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. The accompanying drawings are merely illustrative to facilitate understanding of the invention, and their specific proportions can be adjusted according to design requirements. The vertical relationships of relative elements and the definitions of front / back in the graphics described herein should be understood by those skilled in the art to refer to the relative positions of the components; therefore, they can all be flipped to present the same component, and all of this should fall within the scope disclosed in this specification.

[0048] To reduce cross-contamination of quantum dots, this embodiment employs electrophoretic deposition combined with photolithography and patterning techniques to deposit quantum dots in stages, thereby fabricating a quantum dot color conversion layer. This layer is then bonded to a Micro-LED chip to create a high-quality Micro-LED full-color display device with low light crosstalk. The quantum dot color conversion layer is fabricated by controlling the positive and negative electrodes of the electrophoresis process to sequentially deposit different quantum dot solutions onto a transparent substrate. To minimize quantum dot deposition outside the transparent electrode area on the substrate surface, an opaque conductive metal layer is deposited and patterned on the surface. The opaque conductive metal layer has the same charge as the quantum dots, effectively repelling quantum dot solutions of the same polarity and preventing quantum dot solutions from remaining on the surface. Furthermore, its opaque nature reduces light crosstalk between sub-pixels.

[0049] Example 1

[0050] refer to Figure 1 The fabrication steps of Micro-LED light-emitting chips are as follows:

[0051] 1) Fabrication of blue LED epitaxial layer 11. A buffer layer 112, an n-GaN layer 113, a blue InGaN / GaN multi-quantum well active region 114, and a p-GaN layer 115 are sequentially grown on a substrate 111 (Si substrate, sapphire, SiC, gallium nitride, etc.) using MOCVD process to obtain the blue LED epitaxial layer.

[0052] 2) MESA Etching. A hard mask of silicon dioxide or silicon nitride (600nm) is deposited on the surface of the epitaxial layer using plasma chemical vapor deposition (PECVD) or atomic deposition. A hard mask agent (HMDS) and photoresist are then spin-coated onto the hard mask. After exposure and development, the hard mask layer is patterned by dry etching (ICP). ICP etching is then performed to a depth of 1.2-1.4 micrometers to fabricate the P and N mesa of the Micro-LED device, which are then separated to form several chip units.

[0053] 3) Deposition of ITO current spread layer. A patterned ITO current spread layer 12 is deposited on the P-plane of the epitaxial layer using electron beam evaporation or telemetry sputtering.

[0054] 4) P and N electrode metal deposition and black photoresist filling. After photolithography and development, reflective electrode metals such as Ti / Al / Ti / Au or Ni / Ag are deposited on the P and N mesa of the chip as P electrode metal layer 13 and N electrode metal layer 14 by electron beam evaporation. After electrode deposition, black photoresist is spin-coated onto the substrate surface, and after photolithography and development, black photoresist 15 is filled between adjacent chip units.

[0055] 5) Substrate bonding. The electrode surfaces of the Micro-LED chip with the P and N electrode metal layers deposited are bonded to the CMOS / TFT driving substrate 17 using In solder 16.

[0056] 6) Substrate and buffer layer removal. The substrate 111 and buffer layer 112 are removed by laser lift-off, mechanical polishing, chemical etching, or a combination of both, exposing the n-GaN layer 113. The final flip-chip Micro-LED light-emitting chip serves as the excitation source, with a peak wavelength of 450nm for each chip in the array.

[0057] The preparation steps of the quantum dot color conversion layer are as follows:

[0058] 1) Fabrication of a transparent electrode layer. An ITO layer with a thickness of 100 nm is deposited on the surface of a transparent substrate 21, such as glass, using photolithography combined with electron beam evaporation or telemetry sputtering. The ITO layer is then patterned using dry etching (ICP) or wet etching (BOE solution, ITO etchant) to obtain an ITO transparent electrode layer with an interdigitated electrode structure. This includes a first transparent electrode 22a and a second transparent electrode 22b. The first transparent electrode 22a and the second transparent electrode 22b each include a longitudinal electrode strip and several transverse electrode strips. The transverse electrode strips are arranged in parallel and one end is connected to the corresponding longitudinal electrode strip. The two longitudinal electrode strips are located on opposite sides, and the transverse electrode strips are located between the two longitudinal electrode strips, forming an interdigitated structure. Figure 2 As shown.

[0059] 2) Insulating Layer Deposition and Aperture Formation. An insulating layer 23, such as a silicon dioxide or silicon nitride thin film with a thickness of 100 nm, is deposited on the structure formed in step 1) using plasma chemical vapor deposition (PECVD) or atomic deposition. After photolithography and development, the insulating layer 23 is subjected to dry etching (ICP) or wet etching (BOE solution, ITO etching solution) to form an array of openings 231 on the transverse electrode fingers of the first transparent electrode 22a and the second transparent electrode 22b. The bottom of the openings exposes ITO, which serves as the quantum dot deposition areas 221a and 221b of the patterned array. Simultaneously, openings 232 are formed on the longitudinal electrode strips of the first transparent electrode 22a and the second transparent electrode 22b, with the bottom of the openings exposing ITO, which serves as the electrical contact areas 222a and 222b. A top view is shown below. Figure 3 As shown.

[0060] 3) Deposition and opening of the opaque conductive metal layer. An opaque conductive metal layer 24 is deposited on the insulating layer 23 using electron beam evaporation. In this embodiment, a chromium layer is deposited using magnetron sputtering, with the RF power set to 80W, argon flow rate at 120 / 60 sccm, gas pressure at 5 Pa, pre-sputtering time set to 20s, and formal sputtering time at 20 minutes, resulting in an opaque chromium layer with a thickness of 50nm. Using photoresist as a mask, an etchant solution prepared with cerium ammonium nitrate, acetic acid, and deionized water is used to pattern the opaque conductive metal layer 24, forming openings. These openings correspond to the quantum dot deposition areas 221a and 221b, and form an array of openings corresponding to the blue light transmission area B (the bottom exposed insulating layer 23). This array of openings forms a sub-pixel array, as well as openings corresponding to the electrical contact areas 222a and 222b. (Top view as shown) Figure 4 As shown, the screenshot in the a-a' direction is as follows: Figure 5 As shown, each sub-pixel is insulated from the others by an insulating layer 23.

[0061] 4) Preparation and electrophoretic deposition of negatively charged red and green quantum dot solutions. In this example, sodium dodecyl phosphate solution was mixed with CdSe red quantum dot material with a particle diameter of 10 nm at 135 °C and stirred for 10-15 min to prepare a negatively charged red quantum dot solution with a concentration of 0.3 mol / L. At the same time, sodium oleate solution was mixed with CdSe green quantum dot material with a particle diameter of 5 nm to prepare a negatively charged green quantum dot solution with a concentration of 0.5 mol / L.

[0062] Red quantum dot electrophoretic deposition. The positive electrode of the electrophoresis apparatus is connected to the electrical contact region 222a of the red quantum dots to be deposited, and the opaque conductive metal layer 24 and the electrical contact region 222b of the green quantum dots to be deposited are connected to the negative electrode. The apparatus is placed in an electrophoresis solution bath containing a red quantum dot solution with negative charges. The circuit is turned on to perform the deposition of red quantum dots. The electrophoresis apparatus is as follows: Figure 6 As shown, a DC electric field with a voltage of 3-10V and a current of 10-30A is used to deposit red quantum dots (R) in the conductive quantum dot deposition region 221a based on the principle of opposite attraction. After deposition, the quantum dot pattern is cured by ultraviolet light, as shown in the figure. Figure 7 .

[0063] Electrophoretic deposition of green quantum dots. The positive electrode of the electrophoresis apparatus is connected to the electrical contact region 222b of the green quantum dots to be deposited, and the opaque conductive metal layer 24 and the electrical contact region 222a are connected to the negative electrode. The apparatus is placed in an electrophoresis solution bath containing a green quantum dot solution with negative charges. The circuit is turned on to perform the deposition of green quantum dots. The electrophoresis apparatus is as follows: Figure 8 As shown, a DC electric field with a voltage of 5-12V and a current of 20-25A is used to deposit green quantum dots G patterns in the conductive quantum dot deposition region 221b based on the principle of opposite attraction. After deposition, the quantum dot pattern structure is cured by ultraviolet light. Figure 9 and Figure 10 Thus, a quantum dot color conversion layer is obtained.

[0064] 5) The n-GaN layer 113 of the flip-chip blue Micro-LED chip 1 is bonded to the transparent substrate 21 of the quantum dot color conversion layer 2 using a high-precision bonding machine. Each sub-pixel corresponds one-to-one with a chip unit, resulting in a full-color display device, such as... Figure 11 As shown.

[0065] Example 2

[0066] The Micro-LED light-emitting chip in Example 2 is an ultraviolet Micro-LED chip.

[0067] The preparation steps of the quantum dot color conversion layer are as follows:

[0068] 1) Fabrication of a first transparent electrode and a second transparent electrode. Referring to Example 1, the following was obtained: Figure 2 The structure shown.

[0069] 2) Deposition and opening of the first insulating layer. Referring to Example 1, the following is obtained: Figure 3 The structure shown.

[0070] 3) Fabrication of the third electrode. Combining photolithography with electron beam evaporation or telemetry sputtering, a third electrode 25 pattern is formed by local deposition on the surface of the insulating layer 23. The third electrode 25 also includes a longitudinal electrode strip and several transverse electrode fingers. The transverse electrode fingers, along with the transverse electrode fingers of the first and second transparent electrodes, are arranged alternately and parallel to each other, with one end connected to the longitudinal electrode strip. For example, the longitudinal electrode strip can be located on the same side as the longitudinal electrode strip of the first transparent electrode, but the two are offset. Figure 12 As shown.

[0071] 4) Deposition and opening of the second insulating layer. A second insulating layer 26, such as a silicon dioxide or silicon nitride thin film with a thickness of 100 nm, is deposited on the structure formed in step 3) using plasma chemical vapor deposition (PECVD) or atomic deposition. After photolithography and development, the second insulating layer 26 is subjected to dry etching (ICP) or wet etching (BOE solution, ITO etching solution) to form an array of openings on the transverse electrode fingers of the first transparent electrode 22a, the second transparent electrode 22b, and the third electrode 25. The bottom of the openings exposes ITO, which serves as the quantum dot deposition areas 221a, 221b, and 251 of the patterned array. Simultaneously, openings are formed on the longitudinal electrode strips of the first transparent electrode 22a, the second transparent electrode 22b, and the third electrode 25, exposing the electrical contact areas 222a and 222b at the bottom of the openings and forming the electrical contact area 252. The top view is shown below. Figure 13 As shown.

[0072] 3) Deposition and opening of the opaque conductive metal layer. A conductive and opaque metal film is deposited on the second insulating layer 26 by electron beam evaporation as an opaque conductive metal layer 24. Openings are patterned into the opaque conductive metal layer 24, including an array of openings corresponding to the quantum dot deposition regions 221a, 221b, and 251, and openings corresponding to the electrical contact regions 222a, 222b, and 252, as shown below. Figure 14 and Figure 15 As shown. For specific process details, please refer to Example 1.

[0073] 4) Preparation and electrophoretic deposition of negatively charged red, green, and blue quantum dot solutions. The red and green quantum dot solutions are the same as in Example 1. The blue quantum dot solution is prepared by mixing sodium dodecyl phosphate solution with ZnS, a blue quantum dot material with a particle diameter of 5 nm, to prepare a negatively charged blue quantum dot solution with a concentration of 0.4 mol / L.

[0074] Red quantum dot electrophoretic deposition. Electrophoresis apparatus such as... Figure 16 The positive electrode of the electrophoresis apparatus is connected to the electrical contact region 222a where red quantum dots are to be deposited. The opaque conductive metal layer 24, the electrical contact region 222b where green quantum dots are to be deposited, and the electrical contact region 252 where blue quantum dots are to be deposited are connected to the negative electrode. The apparatus is then placed in an electrophoresis solution bath containing a red quantum dot solution with negative charges. The circuit is turned on to deposit red quantum dots, forming a red quantum dot R pattern in the quantum dot deposition region 221a. The electrophoresis parameters are as described in Example 1.

[0075] Green quantum dot electrophoretic deposition. The positive electrode of the electrophoresis apparatus is connected to the electrical contact region 222b where green quantum dots are to be deposited. The opaque conductive metal layer 24, electrical contact regions 222a and 252 are connected to the negative electrode. The apparatus is placed in an electrophoresis solution bath containing a green quantum dot solution with negative charges. The circuit is turned on to deposit green quantum dots, forming a green quantum dot G pattern in the quantum dot deposition region 221b. Electrophoresis parameters are as described in Example 1.

[0076] Blue quantum dot electrophoretic deposition. The positive electrode of the electrophoresis apparatus is connected to the electrical contact region 252 where blue quantum dots are to be deposited. The opaque conductive metal layer 24 and electrical contact regions 222a and 222b are connected to the negative electrode. The apparatus is placed in an electrophoresis solution bath containing a blue quantum dot solution with negative charges. The circuit is turned on to deposit blue quantum dots. A DC electric field voltage of 5-8V and a current of 10-15A are used. Based on the principle of attraction between opposite charges, a blue quantum dot pattern B is deposited in the conductive quantum dot deposition region 251, thus obtaining a three-color quantum dot color conversion layer, such as... Figure 17 As shown.

[0077] The ultraviolet Micro-LED chip is bonded to the transparent substrate of the three-color quantum dot color conversion layer 2 using a high-precision bonding machine. The sub-pixels correspond one-to-one with the chip units to obtain a full-color display device.

[0078] The above embodiments are only used to further illustrate a method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for fabricating a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots, characterized in that, Includes the following steps: 1) A transparent electrode layer is formed on a transparent substrate, the transparent electrode layer including a first transparent electrode and a second transparent electrode that do not contact each other; the first transparent electrode and the second transparent electrode each include an electrode strip and a plurality of electrode fingers arranged at intervals, the ends of the electrode fingers are connected to the electrode strip, and the electrode fingers of the first transparent electrode and the second transparent electrode are arranged alternately. 2) An insulating layer is deposited on the transparent electrode layer, the insulating layer is patterned, and several openings are formed on each electrode finger strip as quantum dot deposition areas, and openings on the electrode strip are formed as electrical contact areas. 3) Deposit an opaque conductive metal layer on the insulating layer, and pattern the opaque conductive metal layer to correspond to the openings of the quantum dot deposition area and the electrical contact area; 4) Deposit the first quantum dot and the second quantum dot respectively to form quantum dot sub-pixel units; When depositing the first quantum dot, one of the positive and negative electrodes of the electrophoresis apparatus is connected to the electrical contact area of ​​the first transparent electrode, and the other electrode is connected to the electrical contact area of ​​the opaque conductive metal layer and the second transparent electrode, and then placed in an electrophoresis pool containing the first quantum dot solution. The surface electrical properties of the first quantum dot are opposite to the polarity of the electrical contact area of ​​the first transparent electrode, and the same as the electrical properties of the opaque conductive metal layer and the electrical contact area of ​​the second transparent electrode. The conductive circuit enables the first quantum dot to be deposited in the quantum dot deposition area of ​​the first transparent electrode, and then it is cured after deposition. When depositing the second quantum dot, one of the positive and negative electrodes of the electrophoresis apparatus is connected to the electrical contact area of ​​the second transparent electrode, and the other electrode is connected to the electrical contact area of ​​the opaque conductive metal layer and the first transparent electrode. The apparatus is then placed in an electrophoresis pool containing a solution of the second quantum dot. The surface charge of the second quantum dot is opposite to the polarity of the electrical contact area of ​​the second transparent electrode, but the same as the polarity of the electrical contact area of ​​the opaque conductive metal layer and the first transparent electrode. The circuit is turned on so that the second quantum dot is deposited in the quantum dot deposition area of ​​the second transparent electrode. After deposition, the quantum dot is cured.

2. The method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to claim 1, characterized in that: The electrophoresis device uses a DC electric field with a voltage of 3~15V and a current of 10~30A.

3. The method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to claim 1, characterized in that: The transparent electrode layer is made of ITO and has a thickness of 50-100 nm; the insulating layer has a thickness of 100-300 nm.

4. The method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to claim 1, characterized in that: The first quantum dot and the second quantum dot are red quantum dots and green quantum dots, respectively. The array of alternating electrode fingers of the first transparent electrode and the second transparent electrode also has a reserved blue light transmission area. In steps 2) and 3), when the insulating layer and the opaque conductive metal layer are patterned, openings are simultaneously formed in the blue light transmission area.

5. The method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to claim 1, characterized in that: Before step 3), steps 1) and 2) are repeated to form a multilayer structure in which transparent electrode layers and insulating layers are alternately stacked, wherein the transparent electrode layers do not contact each other, and the projections of the electrode fingers and electrode strips of different transparent electrode layers on the transparent substrate do not overlap.

6. The method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to claim 5, characterized in that: It includes two transparent electrode layers, wherein the first transparent electrode layer includes a first transparent electrode and a second transparent electrode that are not in contact with each other, and the second transparent electrode layer includes a third transparent electrode. The electrode fingers of the first transparent electrode, the second transparent electrode and the third transparent electrode are alternately arranged on the transparent substrate.

7. The method for preparing a color conversion layer for a full-color device based on electrophoretic deposition of quantum dots according to claim 6, characterized in that: Red quantum dots, green quantum dots, and blue quantum dots are deposited in the quantum dot deposition regions of the first transparent electrode, the second transparent electrode, and the third transparent electrode, respectively.

8. A method for fabricating a full-color device, characterized in that, Including the following steps: 1) Provide a Micro-LED light-emitting chip, wherein the Micro-LED light-emitting chip has a plurality of light-emitting units; 2) The color conversion layer is prepared using the method for preparing a full-color device based on electrophoretic deposition of quantum dots as described in any one of claims 1 to 7; 3) The transparent substrate of the color conversion layer is bonded to the Micro-LED light-emitting chip, wherein the quantum dot sub-pixel unit corresponds one-to-one with the light-emitting unit.

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