High-efficiency Micro-LED quantum dot color conversion layer and preparation method thereof

Abstract

The invention discloses a high-efficiency Micro-LED quantum dot color conversion layer and a preparation method thereof, and the method comprises the steps: uniformly injecting a quantum dot solution into a pre-prepared nano-porous structure epitaxial wafer through a spraying technology under the protection of inert gas; placing the epitaxial wafer after quantum dot injection in air for oxygen treatment; and cleaning and drying the epitaxial wafer subjected to oxygen treatment to obtain the epitaxial wafer. The quantum dots on the surfaces of the nanopores are subjected to oxidation treatment, so that an oxidation film is formed on the surfaces, and the oxidation film serving as a physical barrier can effectively block permeation of oxygen and moisture in the environment and can keep the integrity of the nanopore structure without affecting the light extraction efficiency; the breakthrough technology provides a key solution for commercial application of the quantum dots in the high-end display field, and is expected to promote the large-scale industrialization process of the quantum dot display technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum dot light-emitting technology, and particularly relates to a high-efficiency Micro-LED quantum dot color conversion layer. The present invention also relates to a preparation method of the high-efficiency Micro-LED quantum dot color conversion layer. Background Art

[0002] Quantum dots are zero-dimensional semiconductor nanomaterials with a physical size close to the exciton Bohr radius and having a quantum confinement effect. Compared with traditional phosphor conversion technology, quantum dot materials have become the core light-emitting materials for a new generation of display technologies due to their precisely tunable emission wavelength (adjusted by material composition and particle size), narrow emission half-width (FWHM < 30 nm), and excellent color purity.

[0003] Especially in the field of Micro-LED displays, quantum dot photoluminescent devices are regarded as the most promising display technology direction after OLEDs due to their advantages such as wide color gamut (more than 120% of the Rec.2020 standard), high brightness (> 1000 nits), fast response (nanosecond level), and low energy consumption. However, the reliability issues of quantum dots in display applications severely restrict their industrialization process. The current mainstream solution is to integrate quantum dots into a nanoporous structure color conversion layer through processes such as spin coating or spraying. This method faces two key challenges: First, it is difficult to control the effective loading amount of quantum dots in the porous structure. Usually, increasing the pore size and pore depth is required to improve the loading amount. However, in fact, when the pore size is increased, it is easier to wash out the quantum dots in the pores during cleaning, resulting in a smaller injection amount. Moreover, increasing the pore size and pore depth will also significantly reduce the protection effect on quantum dots. Second, there are a large number of coordinatively unsaturated bonds and dangling bonds on the surface of quantum dots, which are prone to non-radiative recombination under the action of environmental factors (oxygen, moisture), leading to severe fluorescence quenching and lifetime decay. To address this technical bottleneck, the present invention proposes a surface oxidation passivation process. By oxidizing the quantum dots on the surface of the nanopores, an oxide film is formed on the surface, which can effectively block the penetration of oxygen and moisture in the environment as a physical barrier, and can also maintain the integrity of the nanoporous structure without affecting the light extraction efficiency. This breakthrough technology provides a key solution for the commercial application of quantum dots in the high-end display field and is expected to promote the large-scale industrialization process of quantum dot display technology. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-efficiency Micro-LED quantum dot color conversion layer, which solves the problems that the existing quantum dot protection scheme in nanopores results in a small injection amount of quantum dots in the nanopores and poor stability.

[0005] Another purpose of the present invention is to provide a preparation method of the high-efficiency Micro-LED quantum dot color conversion layer.

[0006] The first technical solution adopted by the present invention is: a method for preparing a high-efficiency Micro-LED quantum dot color conversion layer, comprising the following steps: Step 1: Under the protection of an inert gas, uniformly inject a quantum dot solution into a pre-prepared nano-porous structure epitaxial wafer through a spraying process; Step 2: Place the epitaxial wafer after the quantum dot injection in the air for oxygen exposure treatment, and passivate the surface defect states of the quantum dots by in-situ forming a dense oxide protection layer on the surface of the quantum dots; Step 3: Clean the epitaxial wafer after the oxygen exposure treatment to remove the quantum dot aggregates on the surface of the epitaxial wafer that have not entered the nano-pores, and obtain the product after drying.

[0007] The characteristics of the first technical solution of the present invention also lie in that In Step 1, the wafer epitaxial wafer with a nano-porous structure is fixed on a spraying machine stage for the spraying process.

[0008] In Step 1, the distance between the spraying machine nozzle and the epitaxial wafer is controlled to be 5-20 cm, the concentration of the spraying solution is 1-50 mg / mL, and the flow rate of the nozzle is 1-50 ml / min.

[0009] The epitaxial wafer material in Step 1 is Si or GaN.

[0010] The oxygen exposure time in Step 2 is 1-50 min, the temperature is 10-80 °C, and the humidity is 10-70%RH.

[0011] The cleaning solution for cleaning in Step 3 is one of toluene, chloroform, n-hexane, dodecanol, ethylene glycol methyl ether, and propylene glycol methyl ether.

[0012] The cleaning rotation speed for cleaning in Step 3 is 300-3000 rpm, and the cleaning time is 1-120 s.

[0013] The second technical solution adopted by the present invention is: a high-efficiency Micro-LED quantum dot color conversion layer, prepared by using the above-mentioned method for preparing a high-efficiency Micro-LED quantum dot color conversion layer.

[0014] The beneficial effects of the present invention are as follows: For the high-efficiency Micro-LED quantum dot color conversion layer and its preparation method of the present invention, after injecting quantum dots into the epitaxial wafer with a porous structure by spraying and then performing oxygen exposure treatment, surface passivation and stabilization of the quantum dots can be achieved, thereby forming a dense oxide protective layer on the surface of the quantum dots through controllable oxidation. First, oxygen molecules combine with the uncoordinated dangling bonds on the surface of the quantum dots, effectively reducing the density of surface defect states and enabling effective improvement of the fluorescence quantum efficiency. Second, the formed oxide thin layer can block environmental erosion in subsequent processes, improving the stability of the device. Therefore, without increasing the pore size and pore depth, the injection amount can be increased and the protection effect on the quantum dots can be improved through oxygen exposure treatment, effectively promoting the application of nanoporous quantum dots in micro-display devices such as Mini / Micro-LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the principle of step 1 in the preparation method of the high-efficiency Micro-LED quantum dot color conversion layer of the present invention; Figure 2 is a schematic diagram of the principle of step 2 in the preparation method of the high-efficiency Micro-LED quantum dot color conversion layer of the present invention; Figure 3 is a schematic diagram of the principle of step 3 in the preparation method of the high-efficiency Micro-LED quantum dot color conversion layer of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] The present invention provides a preparation method for a high-efficiency Micro-LED quantum dot color conversion layer, comprising the following steps: Step 1: As Figure 1 shown, in a clean room environment, fix the Si or GaN wafer epitaxial wafer with a porous nanostructure on the spraying machine stage, control the distance between the nozzle and the sample to be 5 - 20 cm, and uniformly inject the quantum dot solution into the pre-prepared nanoporous epitaxial wafer through the spraying process. The solution concentration is 1 - 50 mg / mL, and the nozzle flow rate is 1 - 50 mL / min. The entire spraying process is carried out under the protection of an inert gas to prevent oxidation and degradation of the quantum dots.

[0018] Step 2: As Figure 2 shown, place the epitaxial wafer with the quantum dots already injected in the air for oxidation treatment. The oxygen exposure time is 1 - 50 min, the temperature is 10 - 80 °C, and the humidity is 10 - 70%RH. This oxidation process forms a dense oxide protective layer in-situ on the surface of the quantum dots, effectively passivating the surface defect states of the quantum dots.

[0019] Step 3: AsFigure 3 As shown in Figure 3 , the epitaxial wafer after oxidation treatment is cleaned. The cleaning solution is one of toluene, chloroform, n - hexane, dodecanol, ethylene glycol methyl ether, and propylene glycol methyl ether. The cleaning rotation speed is 300 - 3000 rpm, and the cleaning time is 1 - 120 s to remove the quantum dot aggregates on the surface that have not entered the pores; after cleaning, the sample is dried.

[0020] Through the above - mentioned method, according to the data in Table 1 below, by comparing Example 1 and Example 2, under the condition that the cleaning rotation speed and the oxygen exposure time remain the same, extending the cleaning time will cause a significant decrease in the quantum dot injection amount. By comparing Example 2 and Example 3, under the condition that the cleaning conditions (rotation speed, oxygen exposure time, cleaning time) are exactly the same, extending the oxygen exposure time can increase the quantum dot injection amount. Example 3 and Example 4 further show that when the oxygen exposure time and the cleaning time are fixed, increasing the cleaning rotation speed will decrease the quantum dot injection amount. Through the comparison of the above - mentioned examples, the present invention realizes the programmable control of the quantum dot injection amount by precisely regulating the oxygen exposure time, cleaning time, and cleaning rotation speed. This method breaks through the bottleneck that it is difficult to precisely regulate the quantum dot injection amount in traditional processes, effectively achieves the purpose of protecting quantum dots and improving reliability, and provides a mass - producible solution for the high - efficiency Micro - LED quantum dot color conversion layer.

[0021] Table 1 Control parameters of Examples 1 - 7

[0022] Example 1 Step 1: In a clean - room environment, fix the wafer epitaxial wafer with a porous nanostructure on the spraying machine stage. Uniformly inject the quantum dot solution onto the pre - prepared nanostructured epitaxial wafer on the wafer surface through the spraying process. The distance between the nozzle and the sample is 10 cm, the solution concentration is 15 mg / mL, and the nozzle flow rate is 20 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0023] Step 2: Place the epitaxial wafer that has completed quantum dot injection in the air for oxidation treatment. The oxygen exposure time is 20 min, and the temperature is 20 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in - situ forming a dense oxide protection layer on the surface of quantum dots.

[0024] Step 3: Clean the oxidized epitaxial wafer. The cleaning solution is toluene. The cleaning rotation speed is 1200 rpm, and the cleaning time is 20 s to remove the quantum dot aggregates on the surface that have not entered the pores; after cleaning, the sample is dried. The QD injection amount of the epitaxial wafer that has completed quantum dot injection is 90 mg.

[0025] Example 2 Step 1: In a cleanroom environment, fix the wafer epitaxial sheet with a porous nanostructure on the spraying machine stage. Through the spraying process, uniformly inject the quantum dot solution onto the surface of the wafer into the pre-prepared nanostructured porous epitaxial sheet. The distance between the nozzle and the sample is 10 cm, the solution concentration is 15 mg / mL, and the nozzle flow rate is 20 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0026] Step 2: Place the epitaxial sheet that has completed the quantum dot injection in the air for oxidation treatment. The oxygen exposure time is 20 min and the temperature is 25 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in-situ forming a dense oxide protection layer on the surface of the quantum dots.

[0027] Step 3: Clean the oxidized epitaxial sheet. The cleaning solution is n-hexane. The cleaning rotation speed is 1200 rpm and the cleaning time is 32 s to remove the quantum dot aggregates on the surface that have not entered the pores. After cleaning, dry the sample. The QD injection amount of the epitaxial sheet that has completed the quantum dot injection is 82 mg.

[0028] Example 3 Step 1: In a cleanroom environment, fix the wafer epitaxial sheet with a porous nanostructure on the spraying machine stage. Through the spraying process, uniformly inject the quantum dot solution onto the surface of the wafer into the pre-prepared nanostructured porous epitaxial sheet. The distance between the nozzle and the sample is 10 cm, the solution concentration is 15 mg / mL, and the nozzle flow rate is 20 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0029] Step 2: Place the epitaxial sheet that has completed the quantum dot injection in the air for oxidation treatment. The oxygen exposure time is 25 min and the temperature is 27 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in-situ forming a dense oxide protection layer on the surface of the quantum dots.

[0030] Step 3: Clean the oxidized epitaxial sheet. The cleaning solution is n-hexane. The cleaning rotation speed is 1200 rpm and the cleaning time is 32 s to remove the quantum dot aggregates on the surface that have not entered the pores. After cleaning, dry the sample. The QD injection amount of the epitaxial sheet that has completed the quantum dot injection is 110 mg.

[0031] Example 4 Step 1: In a cleanroom environment, fix the wafer epitaxial sheet with a porous nanostructure on the spraying machine stage. Through the spraying process, uniformly inject the quantum dot solution onto the surface of the wafer into the pre-prepared nanostructured porous epitaxial sheet. The distance between the nozzle and the sample is 10 cm, the solution concentration is 15 mg / mL, and the nozzle flow rate is 20 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0032] Step 2: Place the epitaxial wafer with completed quantum dot injection in air for oxidation treatment. The oxygen exposure time is 25 min and the temperature is 30 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in-situ forming a dense oxide protection layer on the surface of quantum dots.

[0033] Step 3: Clean the oxidized epitaxial wafer. The cleaning solution is n-hexane. The cleaning rotation speed is 2800 rpm and the cleaning time is 32 s to remove the quantum dot aggregates on the surface that have not entered the pores. After cleaning, dry the sample. The QD injection amount of the epitaxial wafer with completed quantum dot injection is 100 mg.

[0034] Example 5 Step 1: In a clean room environment, fix the wafer epitaxial wafer with a porous nanostructure on the spraying machine stage. Uniformly inject the quantum dot solution onto the pre-prepared nanostructured epitaxial wafer on the wafer surface through a spraying process. The distance between the nozzle and the sample is 10 cm, the solution concentration is 15 mg / mL, and the nozzle flow rate is 20 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0035] Step 2: Place the epitaxial wafer with completed quantum dot injection in air for oxidation treatment. The oxygen exposure time is 35 min and the temperature is 26 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in-situ forming a dense oxide protection layer on the surface of quantum dots.

[0036] Step 3: Clean the oxidized epitaxial wafer. The cleaning solution is n-hexane. The cleaning rotation speed is 1200 rpm and the cleaning time is 20 s to remove the quantum dot aggregates on the surface that have not entered the pores. After cleaning, dry the sample. The QD injection amount of the epitaxial wafer with completed quantum dot injection is 130 mg.

[0037] Example 6 Step 1: In a clean room environment, fix the wafer epitaxial wafer with a porous nanostructure on the spraying machine stage. Uniformly inject the quantum dot solution onto the pre-prepared nanostructured epitaxial wafer on the wafer surface through a spraying process. The distance between the nozzle and the sample is 5 cm, the solution concentration is 1 mg / mL, and the nozzle flow rate is 1 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0038] Step 2: Place the epitaxial wafer with completed quantum dot injection in air for oxidation treatment. The oxygen exposure time is 1 min and the temperature is 10 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in-situ forming a dense oxide protection layer on the surface of quantum dots.

[0039] Step 3: Clean the epitaxial wafer after oxidation treatment. The cleaning solution is chloroform. The cleaning rotation speed is 300 rpm and the cleaning time is 1 s to remove the quantum dot aggregates on the surface that did not enter the pores. After cleaning, dry the sample. The QD injection amount of the epitaxial wafer with completed quantum dot injection is 40 mg.

[0040] Example 7 Step 1: In a cleanroom environment, fix the wafer epitaxial wafer with a porous nanostructure on the spraying machine stage. Uniformly inject the quantum dot solution into the pre-prepared nanoporous structure epitaxial wafer on the wafer surface through the spraying process. The distance between the nozzle and the sample is 20 cm, the solution concentration is 50 mg / mL, and the nozzle flow rate is 50 mL / min. The entire spraying process is carried out under the protection of inert gas to prevent the oxidation and degradation of quantum dots.

[0041] Step 2: Place the epitaxial wafer with completed quantum dot injection in the air for oxidation treatment. The oxygen exposure time is 50 min and the temperature is 80 °C. This oxidation process effectively passivates the surface defect states of quantum dots by in-situ forming a dense oxide protection layer on the surface of quantum dots.

[0042] Step 3: Clean the epitaxial wafer after oxidation treatment. The cleaning solution is dodecanol. The cleaning rotation speed is 3000 rpm and the cleaning time is 120 s to remove the quantum dot aggregates on the surface that did not enter the pores. After cleaning, dry the sample. The QD injection amount of the epitaxial wafer with completed quantum dot injection is 125 mg.

Claims

1. Preparation method of high-efficiency Micro-LED quantum dot color conversion layer, characterized in that, It includes the following steps: Step 1: Under the protection of inert gas, uniformly inject the quantum dot solution into the pre-prepared nano-porous structure epitaxial wafer through a spraying process; Step 2: Place the epitaxial wafer with quantum dots injected in air for oxygen exposure treatment, and passivate the surface defect states of the quantum dots by in-situ forming a dense oxide protection layer on the surface of the quantum dots; Step 3: Clean the epitaxial wafer after oxygen exposure treatment to remove the quantum dot aggregates on the surface of the epitaxial wafer that have not entered the nano-pores, and obtain it after drying.

2. The preparation method of the high-efficiency Micro-LED quantum dot color conversion layer according to claim 1, wherein, In Step 1, the wafer epitaxial wafer with a nano-porous structure is fixed on the spraying machine stage for the spraying process.

3. The preparation method of the high-efficiency Micro-LED quantum dot color conversion layer according to claim 2, wherein, In Step 1, control the distance between the spraying machine nozzle and the epitaxial wafer to be 5 - 20 cm, the concentration of the spraying solution to be 1 - 50 mg / mL, and the flow rate of the nozzle to be 1 - 50 ml / min.

4. The preparation method of the high-efficiency Micro-LED quantum dot color conversion layer according to claim 1, characterized in that, The material of the epitaxial wafer in Step 1 is Si or GaN.

5. The preparation method of the high-efficiency Micro-LED quantum dot color conversion layer according to claim 1, characterized in that, In Step 2, the oxygen exposure time is 1 - 50 min, the temperature is 10 - 80 °C, and the humidity is 10 - 70%RH.

6. The preparation method of the high-efficiency Micro-LED quantum dot color conversion layer according to claim 1, characterized in that, The cleaning solution for cleaning in Step 3 is one of toluene, chloroform, n-hexane, dodecanol, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

7. The preparation method of the high-efficiency Micro-LED quantum dot color conversion layer according to claim 1, characterized in that In Step 3, the cleaning rotation speed for cleaning is 300 - 3000 rpm, and the cleaning time is 1 - 120 s.

8. High-efficiency Micro-LED quantum dot color conversion layer, characterized in that, It is prepared by using the preparation method of the high-efficiency Micro-LED quantum dot color conversion layer as described in Claims 1 - 7.

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