Micro-LED device based on charge compensation method and preparation method thereof

Abstract

The invention discloses a Micro-LED device based on a charge compensation method and a preparation method of the Micro-LED device, relates to the technical field of nano luminescent materials and display, and solves the problems that the luminous efficiency of the Micro-LED device is reduced, the driving voltage is increased, the service life of the device is shortened and the like due to reduction of the crystal size during Mn < 4 + > doped fluoride nanocrystalline through Mg < 2 + > charge compensation. The Micro-LED device sequentially comprises a driving substrate layer, a blue light Micro-LED array layer, a light extraction layer, a color conversion layer and a packaging layer from bottom to top; the light extraction layer is a titanium dioxide nanoparticle layer; the color conversion layer is a Micro-LED device formed by mixing a solution of dispersed silver silicon core shell-cesium sodium manganese fluoride composite nanomaterial Ag (at) SiO2 / Cs2NaF6: Mn < 4 + > and Mg < 2 + > nanocrystal particles with a methyl methacrylate solution and coating the mixture on a substrate. By introducing the Micro-LED color conversion layer based on the charge compensation method, lattice charge unbalance is neutralized, lattice defects are reduced, and formation of a Micro-LED device with high brightness and high stability is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of nanoluminescent materials and display technology, specifically relating to Micro-LED devices based on charge compensation method and their preparation methods. Background Technology

[0002] With the increasing demand for miniaturization and integration of optoelectronic devices, micro-LED technology has attracted widespread attention in fields such as information display and solid-state lighting due to its advantages such as wide color gamut, high brightness, low power consumption, and long lifespan. Compared with traditional liquid crystal display (LCD) and OLED technologies, Micro-LED can not only achieve more vivid and accurate colors, but also provide more flexible solutions for different application scenarios. However, in order to meet the needs of full-color displays, it is crucial to fabricate efficient, stable, and low-power Micro-LED devices.

[0003] In current mainstream solutions, rare-earth-based Micro-LED devices are difficult to scale up due to element scarcity and high cost; while quantum dot Micro-LED devices offer excellent color gamut, they suffer from reliability issues such as high-temperature ligand decomposition and heavy metal environmental risks. Against this backdrop, manganese-doped fluorides (such as Cs₂NaAlF₆:Mn) are emerging as a promising alternative. 4 Manganese fluoride (MDF) exhibits great potential due to its excellent luminescent properties. These materials not only possess non-toxicity, high luminescent efficiency, and good thermal stability, but their fabrication process is also relatively simple and production costs are low. However, the surface state effect of their nanoscale devices significantly restricts their luminescent performance: when the crystal size shrinks to the nanoscale, the surface defect density surges, leading to non-radiative energy loss, causing the external quantum efficiency (EQE) to drop below 15%, increasing the driving voltage, and causing a sharp decline in lifetime under high temperature and humidity environments, severely hindering the industrialization of Micro-LEDs. Therefore, how to optimize the crystal structure of manganese fluoride-doped materials, reduce surface defects, and improve the luminescent efficiency of Micro-LED devices has become a crucial issue that urgently needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to provide a Micro-LED device based on the charge compensation method and its fabrication method, aiming to solve the problem of Mn 4+ Fluoride nanocrystals (NCs) exhibit problems such as reduced luminous efficiency, increased driving voltage, and decreased device lifetime in Micro-LED devices due to the reduced crystal size. Introducing Mg... 2+ By performing charge compensation and neutralizing lattice charge imbalance, lattice defects are effectively reduced, and the luminous efficiency of the device is enhanced, providing an efficient and reliable solution for next-generation Micro-LED full-color displays.

[0005] The technical solution of this invention is as follows:

[0006] The Micro-LED device based on charge compensation consists of, from bottom to top, a driving substrate layer, a blue Micro-LED array layer, a light extraction layer, a color conversion layer, and an encapsulation layer; the light extraction layer is a titanium dioxide (TiO2) nanoparticle layer; the color conversion layer is a layer of dispersed silver-silicon core-shell cesium sodium manganese fluoride composite nanomaterials (Ag@SiO2 / Cs2NaF6:Mn). 4+ ), Mg 2+ Micro-LED devices are formed by coating a substrate with a solution of nanocrystalline particles mixed with a solution of methyl methacrylate (PMMA).

[0007] Preferably, the driving substrate is a silicon-based CMOS backplane.

[0008] Preferably, the blue micro-LED array layer is an indium gallium nitride / gallium nitride (InGaN / GaN) multi-quantum-well layer, and the size range of the blue micro-LED array layer is 5-20μm.

[0009] Preferably, the light extraction layer is a titanium dioxide (TiO2) nanoparticle layer with a thickness ranging from 10 to 50 nm.

[0010] Preferably, the color conversion layer is composed of Ag@SiO2 / Cs2NaF6:Mn dispersed in it. 4+ Mg 2+ The nanocrystalline particles were prepared by mixing a solution of nanocrystalline particles with a solution of methyl methacrylate (PMMA), wherein Ag@SiO2 / Cs2NaF6:Mn was dispersed. 4+ Mg 2+ The solution of nanocrystalline particles consists of Cs₂NaF₆:Mn 4+ Mg 2+ The nanocrystals and Ag@SiO2 were prepared by dissolving them in chloroform; the polymethyl methacrylate (PMMA) solution was prepared by dissolving PMMA in acetic acid; the thickness of the color conversion layer ranged from 20 to 200 nm.

[0011] Preferably, the encapsulation layer is a UV-curable epoxy resin with a thickness of 5-10 μm.

[0012] This invention also discloses a method for fabricating Micro-LED devices based on the charge compensation method, the process of which includes the following steps:

[0013] Step 1: Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0014] Step 2: InGaN / GaN Micro-LED epitaxial wafer growth and mass transfer are performed on the dried driving substrate;

[0015] Step 3: Spin-coat the light extraction layer solution onto the blue Micro-LED array layer;

[0016] Step 4: Spin-coat the color conversion layer solution onto the light extraction layer solution;

[0017] Step 5: UV-curing is performed on the color conversion layer to prepare the encapsulation layer;

[0018] As a preferred technical solution, in step 2, the epitaxial wafer growth temperature is 1040℃ (GaN) / 780℃ (InGaN), and the pressure is 2×10⁻⁶. 4 Pa.

[0019] As a preferred technical solution, in step 3, the thermal annealing temperature of the light extraction layer is 100℃ and the time is 5min.

[0020] As a preferred technical solution, in step 4, the step-annealing temperature of the color conversion layer is 100℃ for 5 minutes, and the final annealing temperature is 150℃ for 30 minutes.

[0021] As a preferred technical solution, in step 5, the encapsulation layer is UV cured for 10 minutes.

[0022] The advantages of this invention are:

[0023] 1. By using double perovskite fluoride, its layered structure is Mn 4 ⁺ provides better lattice matching and reduces luminescence quenching due to size effects.

[0024] 2. By introducing Mg 2+ Charge compensation neutralizes lattice charge imbalance, effectively reduces lattice defects, forms a high-brightness red light conversion layer, and enhances the luminous efficiency of Micro-LED devices. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the proportional relationships of the various components in the accompanying drawings do not represent the actual proportional relationships in the material selection and design, but are merely schematic diagrams of the structure or position, wherein:

[0026] Figure 1 This is a schematic diagram of the structure of a Micro-LED device based on the charge compensation method, which relates to the present invention.

[0027] The labels in the attached diagram are as follows: 1-Driver substrate layer, 2-Blue Micro-LED array layer, 3-Light extraction layer, 4-Color conversion layer, 5-Encapsulation layer. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0029] Example 1 (Control Group):

[0030] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0031] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0032] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0033] 4. Spin-coating uncompensated Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (0.2 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0034] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0035] Example 2:

[0036] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0037] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0038] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0039] 4. Spin-coating Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ Mg 2+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (0.2 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0040] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0041] Example 3:

[0042] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0043] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0044] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0045] 4. Spin-coating Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ Mg 2+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (0.4 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0046] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0047] Example 4:

[0048] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0049] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0050] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0051] 4. Spin-coating Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ Mg 2+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (0.6 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0052] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0053] Example 5:

[0054] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0055] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0056] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0057] 4. Spin-coating Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ Mg 2+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (0.8 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0058] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0059] Example 6:

[0060] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0061] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0062] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0063] 4. Spin-coating Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ Mg 2+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (1.0 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0064] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0065] Example 7:

[0066] 1. Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven.

[0067] 2. InGaN / GaN Micro-LED epitaxial wafer growth (growth temperature 1040℃ (GaN) / 780℃ (InGaN)) and mass transfer were performed on the dried driving substrate;

[0068] 3. Prepare a light extraction layer by spin-coating a light extraction layer solution (3000 rpm, 30 s) onto a blue Micro-LED array layer, followed by thermal annealing (100℃, 5 min).

[0069] 4. Spin-coating Ag@SiO2 / Cs2NaF6:Mn onto the surface of a glass substrate. 4+ Mg 2+ A composite functional layer was prepared by spin-coating a mixed solution of nanocrystals (1.2 g) and polymethyl methacrylate (PMMA) at 3000 rpm for 30 s. The solution was spin-coated three times, and after each spin-coating, a heat annealing treatment was performed (100 °C for 5 min). The resulting film was then subjected to a final heat annealing treatment (150 °C for 30 min).

[0070] 5. Prepare an encapsulation layer by UV curing on the color conversion layer;

[0071] The test structures of the control group in Example 1 and devices 2-7 are shown in Table 1.

[0072] Table 1:

[0073] It can be seen that, compared with the untreated Micro-LED device (Example 1), the Micro-LED device based on charge compensation (Examples 2-7) exhibits significantly enhanced internal and external quantum efficiencies, a slightly reduced absorption efficiency, and a lower start-up voltage, resulting in a significant improvement in device performance. This is due to the Mg... 2+ Charge compensation neutralizes lattice charge imbalance, effectively reduces lattice defects, improves the internal and external quantum efficiency of the color conversion layer film, reduces the absorption of incident light by the film, and enhances the luminous efficiency of Micro-LED devices.

[0074] The present invention has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A Micro-LED device based on charge compensation method, characterized in that, From bottom to top, it includes a driving substrate layer, a blue Micro-LED array layer, a light extraction layer, a color conversion layer, and an encapsulation layer.

2. The Micro-LED device based on charge compensation method according to claim 1, characterized in that, The driving substrate is a silicon-based CMOS backplane.

3. The Micro-LED device based on charge compensation method according to claim 1, characterized in that, The blue micro-LED array layer is an indium gallium nitride (InGaN) / gallium nitride (GaN) multi-quantum well layer, and the size range of the blue micro-LED array layer is 5-20 μm.

4. The Micro-LED device based on charge compensation method according to claim 1, characterized in that, The light extraction layer is a titanium dioxide (TiO2) nanoparticle layer, and the thickness of the light extraction layer ranges from 10 to 50 nm.

5. The Micro-LED device based on charge compensation method according to claim 1, characterized in that, The color conversion layer is composed of silver-silicon core-shell cesium sodium manganese fluoride composite nanomaterials Ag@SiO2 / Cs2NaF6:Mn. 4+ Mg 2+ The nanocrystalline particles were prepared by mixing a solution of methyl methacrylate (PMMA) with a solution containing dispersed Ag@SiO2 / Cs2NaF6:Mn. 4+ Mg 2+ The solution of nanocrystalline particles consists of Cs₂NaF₆:Mn 4+ Mg 2+ The nanocrystals and Ag@SiO2 were prepared by dissolving them in chloroform; the polymethyl methacrylate (PMMA) solution was prepared by dissolving PMMA in acetic acid; and the thickness of the color conversion layer was 20-200 nm.

6. The Micro-LED device based on charge compensation method according to claim 1, characterized in that, The encapsulation layer is made of UV-curable epoxy resin with a thickness of 5-10 μm.

7. A method for fabricating Micro-LED devices based on charge compensation, characterized in that, The preparation process includes the following steps: Step 1: Clean the driver substrate with deionized water, isopropanol, and acetone solution. After cleaning, dry it with nitrogen and store it in a constant temperature drying oven. Step 2: InGaN / GaN Micro-LED epitaxial wafer growth and mass transfer are performed on the dried driving substrate; Step 3: Spin-coat the light extraction layer solution onto the blue Micro-LED array layer; Step 4: Spin-coat the color conversion layer solution onto the light extraction layer solution; Step 5: UV-curing is performed on the color conversion layer to prepare the encapsulation layer.

8. The method for fabricating Micro-LED devices based on charge compensation according to claim 7, characterized in that, In step 2, the epitaxial wafer growth temperature is 1040℃ GaN / 780℃ InGaN, and the pressure is 2×10⁻⁶. 4 Pa.

9. The method for fabricating Micro-LED devices based on charge compensation according to claim 7, characterized in that, In step 3, the heat annealing temperature of the light extraction layer is 100℃ and the time is 5min. In step 4, the heat annealing temperature of the color conversion layer is 100℃ and the time is 5min. The final heat annealing temperature is 150℃ and the time is 30min.

10. The method for fabricating Micro-LED devices based on charge compensation according to claim 7, characterized in that, In step 5, the encapsulation layer is UV cured for 10 minutes.

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