Pure red perovskite quantum dot luminescent material and preparation method thereof, and red light Micro-LED device

Abstract

The invention relates to the technical field of quantum dot luminescence and Micro-LED display, in particular to a pure red perovskite quantum dot luminescent material, a preparation method thereof and a red light Micro-LED. The quantum dot luminescent material comprises ligand-modified quantum dots, nano mesoporous spheres and a transparent oxide shell layer, the ligand-modified quantum dots are embedded into surface channels of the nano mesoporous spheres to form M-N composite nano microspheres, and the transparent oxide shell layer coats the surfaces of the M-N composite nano microspheres to form a core-shell structure; the quantum dot modified by the ligand comprises a perovskite quantum dot modified by a triphenylphosphine oxide ligand. The pure red perovskite quantum dot luminescent material provided by the invention has the comprehensive advantages of high blue light absorption rate, high fluorescence quantum efficiency, excellent comprehensive stability, low cost and the like.

Description

Technical Field

[0001] This invention relates to the fields of quantum dot luminescence and Micro-LED display technology, and particularly to a pure red perovskite quantum dot luminescent material and its preparation method, as well as a red Micro-LED. Background Technology

[0002] With the advancement of a new round of technological revolution, the display technology field is undergoing profound changes. Compared with traditional liquid crystal display (LCD) and organic light-emitting diode (OLED) technologies, the emerging Micro-LED display technology exhibits many significant advantages. On the one hand, by miniaturizing LED devices, Micro-LED can use individual micro-LEDs as pixel units, thereby achieving higher resolution and pixel density. On the other hand, due to its use of inorganic materials, Micro-LED has a longer lifespan and excellent environmental stability. Furthermore, this technology also features fast response speed, low power consumption, and excellent visible light communication performance. Therefore, Micro-LED is considered the core of next-generation display technology and has attracted widespread attention from academia and industry. However, red Micro-LED, essential for fields such as augmented reality / virtual reality (AR / VR), smart cars, optical communication, and biomedicine, is severely hampered by size effects, resulting in a lack of high-efficiency, high-brightness red Micro-LEDs. Therefore, the development level of red Micro-LED largely determines the speed of commercial application of Micro-LED technology.

[0003] To address the aforementioned issues, researchers have proposed an alternative solution of "blue-light Micro-LED + red-green quantum dots" (Yingqi Zeng, et al. Full-color micro-LED displays based on quantum dot colorconverters. Nano Research, 2025, 18(6):94907390.). This not only promises to solve the problem of low red light luminous efficiency but also simplifies mass transfer and reduces manufacturing costs. Consequently, major display manufacturers and research institutions both domestically and internationally are actively investing in research on this technology. Cadmium-based quantum dots possess excellent optical properties, high stability, and mature fabrication technology, thus they are widely used in Micro-LED full-color displays (Shenghan Zou, et al. Wafer-scale patterning of high-resolution quantum dot films with a thickness over 10 μm for improved color conversion. Nanoscale, 2023, 15(45):18317.). However, cadmium-based quantum dots still face challenges such as low blue light absorption, high cost, and cadmium content restrictions under the EU RoHS directive. Therefore, there is an urgent need to develop a novel pure red quantum dot material suitable for Micro-LED full-color displays.

[0004] Pure red perovskite quantum dots possess advantages such as nanoscale size, high luminous efficiency, high color purity, and low cost, making them promising candidates for use as red light conversion materials in combination with blue Micro-LED chips to develop high-performance red Micro-LED devices. However, pure red perovskite quantum dots face the following challenges in Micro-LED display applications: 1) Halogen ion segregation. Mixed halide perovskite quantum dots CsPbBr x I 3-xHalogen ions in the light readily undergo phase segregation, forming bromine-rich and iodine-rich domains, leading to broadening and shifting of the emission peak. While colloidal CsPbI3 perovskite quantum dots exhibit a strong quantum size effect, their abundant surface defects exacerbate ion migration and phase instability (Mingjin Li, et al. Enhancing pure red perovskite LEDs via In-Situ etching and pseudohalide passivation of mixed halide quantum dots. Applied Materials Today, 2025, 46:102896. Shuwen Huang, et al. Multifunctional-ligand enabled stable CsPbI3 quantum dots for highly efficient pure-red light-emitting diodes. ACS Applied Materials & Interfaces, 2025, 17(23):34182-34192.). 2) Poor luminescence stability under multiple factors. Although the stability of the two types of pure red perovskite quantum dots under a single factor (air, water, light or heat) can be improved through component engineering and surface ligand passivation, their overall luminescence stability is poor and cannot meet the practical application requirements of Micro-LED (Yi Wei, et al. In situ light-initiated ligands cross-linking enables efficient allsolution-processed perovskite light-emitting diodes. The Journal of Physical Chemistry Letters, 2020, 11(3):1154-1161.). 3) Low blue light excitation color conversion efficiency. The red light conversion films prepared from the above-mentioned pure red perovskite quantum dots have low blue light absorption and low blue light excitation fluorescence quantum efficiency, resulting in blue light leakage and low luminous efficiency in their red light Micro-LED devices (Sunghoon Kim, et al. Highly thin film with aerosol-deposited perovskitequantum dot / metal oxide composite for perfect color conversion and luminanceenhancement. Chemical Engineering Journal, 2022, 441:135991.).

[0005] Therefore, there is an urgent need to develop a low-cost, highly stable, and highly efficient pure red perovskite quantum dot fluorescent microsphere. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a pure red perovskite quantum dot luminescent material, its preparation method, and a red Micro-LED.

[0007] One of the technical solutions provided by this invention is as follows: A pure red perovskite quantum dot luminescent material, comprising ligand-modified quantum dots, mesoporous nanospheres, and a transparent oxide shell, wherein the ligand-modified quantum dots are embedded in the surface pores of the mesoporous nanospheres to form M@N composite nanospheres, and the transparent oxide shell coats the surface of the M@N composite nanospheres to form a core-shell structure; The ligand-modified quantum dots include perovskite quantum dots modified with triphenylphosphine oxide ligands.

[0008] In one embodiment of the present invention, the perovskite quantum dot is CsPbI3.

[0009] In one embodiment of the present invention, the perovskite quantum dots have a particle size of 3~20 nm.

[0010] In one embodiment of the present invention, the nanoporous spheres are mesoporous silica.

[0011] In one embodiment of the present invention, the particle size of the nanoporous spheres is 50~250 nm and / or the pore size of the nanoporous spheres is 3~30 nm.

[0012] In one embodiment of the present invention, the oxide in the transparent oxide shell is aluminum oxide and / or silicon dioxide.

[0013] In one embodiment of the present invention, the thickness of the transparent oxide shell is 0.1~5 nm, preferably 0.1~2 nm.

[0014] In one embodiment of the present invention, the mass percentage of the perovskite quantum dots to the triphenylphosphine oxide ligand is 1 wt% to 30 wt%, preferably 10 wt% to 25 wt%.

[0015] The second technical solution provided by this invention is as follows: A method for preparing a pure red perovskite quantum dot luminescent material includes the following steps: We provide composite nanospheres with ligand-modified quantum dots embedded in surface channels; A transparent oxide shell is formed on the surface of the composite nanospheres; The ligand-modified quantum dots include perovskite quantum dots modified with triphenylphosphine oxide ligands.

[0016] The third technical solution provided by this invention is as follows: A red Micro-LED device includes a pure red perovskite quantum dot luminescent material as described above, or a pure red perovskite quantum dot luminescent material prepared by the preparation method described above.

[0017] Based on the above, the beneficial effects of the present invention compared with the prior art are: (1) The pure red perovskite quantum dot fluorescent microspheres provided by the present invention are easy to mass-produce in industry and have low cost; (2) The pure red perovskite quantum dot fluorescent microspheres provided by the present invention solve the bottleneck problem that it is difficult to achieve both the luminescence performance and comprehensive stability of pure red perovskite quantum dots. (3) The red light Micro-LED prepared by combining the pure red perovskite quantum dot fluorescent microspheres of the present invention with blue light Micro-LED exhibits ultra-high brightness and external quantum efficiency (EQE) due to the local light field modulation that improves the blue light absorption rate and light extraction rate.

[0018] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other beneficial effects of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0020] Figure 1 A schematic diagram of the structure of the pure red perovskite quantum dot luminescent material provided by the present invention; Figure 2 The table shows the performance of pure red perovskite quantum dot luminescent materials in the embodiments and comparative examples of this invention. Figure 3 The table shows the performance of the red Micro-LED devices in the embodiments and comparative examples of this invention. Figure 4 The photoluminescence spectrum of the pure red perovskite quantum dot fluorescent microspheres provided in Example 1 of this invention; Figure 5 The photoluminescence spectrum of the pure red perovskite quantum dots provided in Comparative Example 1 of this invention; Figure 6 This is a transmission electron microscope image of pure red perovskite quantum dot fluorescent microspheres provided in Example 1 of the present invention; Figure 7 It is the red light color conversion array provided in Embodiment 14 of the present invention; Figure 8 This is a fluorescence microscope image of the pure red perovskite quantum dot fluorescent microsphere luminescent array provided in Embodiment 1 of the present invention, with a pixel size of 10 μm; Figure 9 This is the electroluminescence spectrum of the red Micro-LED provided in Embodiment 1 of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0023] An embodiment of the present invention provides a pure red perovskite quantum dot luminescent material, the quantum dot luminescent material comprising ligand-modified quantum dots, mesoporous nanospheres, and a transparent oxide shell, wherein the ligand-modified quantum dots are embedded in the surface pores of the mesoporous nanospheres to form M@N composite nanospheres, and the transparent oxide shell coats the surface of the M@N composite nanospheres to form a core-shell structure; the ligand-modified quantum dots include perovskite quantum dots modified with triphenylphosphine oxide ligands.

[0024] Specifically, in one embodiment of the present invention, the general chemical formula of the quantum dot luminescent material is: MT@N / P; where "M" represents quantum dot; "-" represents surface modification; "T" represents ligand; "@" represents embedding; "N" represents nanoporous sphere; " / " represents core-shell; and "P" represents transparent oxide shell. In the pure red perovskite quantum dot luminescent material provided in this embodiment, the main role of the triphenylphosphine oxide (TPPO) ligand (i) is to react with the Pb on the surface of the CsPbI3 quantum dots. 2+ (ii) Due to its own steric hindrance effect, it can suppress the aggregation of CsPbI3 quantum dots; The main functions of nanoporous spheres are (i) as a framework material, which utilizes the spatial confinement effect to control the confined growth of quantum dots, ensuring the uniformity of quantum dot size, while inhibiting quantum dot aggregation and reducing surface defects and reabsorption effects; (ii) their unique pore structure can effectively enhance the propagation and scattering effects of light, realize local light field modulation, and improve the blue light absorption rate and light extraction rate. The main functions of the transparent oxide shell are (i) to act as a barrier layer, effectively inhibiting the penetration of moisture and oxygen and preventing them from adversely affecting the photoluminescence performance of the internal quantum dots; and (ii) to achieve effective modulation of the light field distribution by precisely controlling the thickness of the shell, thereby improving the photon extraction efficiency.

[0025] In a preferred embodiment of the present invention, the perovskite quantum dot is CsPbI3.

[0026] In a preferred embodiment of the present invention, the perovskite quantum dots have a particle size of 3~20 nm; When the particle size of quantum dots is 3~20 nm, they have advantages such as strong quantum confinement effect, few surface defects, narrow half-width at half-maximum, and high fluorescence quantum yield. When the particle size is less than 3 nm, the huge specific surface area provides a large number of attack sites for water and oxygen, making them easier to degrade. The increase in surface defects reduces their fluorescence quantum yield. When the particle size is greater than 20 nm, the quantum confinement effect weakens, thus reducing the fluorescence quantum yield and failing to meet the requirements of display applications.

[0027] In a preferred embodiment of the present invention, the nanoporous spheres are mesoporous silica.

[0028] In a preferred embodiment of the present invention, the particle size of the nanoporous spheres is 50~250 nm and / or the pore size of the nanoporous spheres is 3~30 nm; The aforementioned mesoporous nanospheres have a particle size of 50–250 nm and a pore size of 3–30 nm. They can fully utilize the spatial confinement effect to control the quantum dot size, suppress quantum dot aggregation, and reduce surface defects and reabsorption effects. Simultaneously, their unique pore structure enables localized optical field modulation, improving blue light absorption and extraction efficiency. When the particle size is less than 50 nm, the number of mesopores on the surface of the nanospheres is relatively small, resulting in low quantum dot carrying efficiency. When the particle size is greater than 250 nm, the increased pore size makes it easier for internal quantum dots to aggregate and reabsorb, leading to fluorescence quenching. Furthermore, due to the larger particle size, sedimentation is prone to occur during subsequent film preparation, resulting in reduced luminescence uniformity.

[0029] In a preferred embodiment of the present invention, the oxides in the transparent oxide shell are aluminum oxide and / or silicon dioxide, which have excellent chemical stability, high light transmittance, and high refractive index. They can not only effectively isolate the quantum dots from the erosion of water and oxygen, but also effectively modulate the light field distribution, thereby improving the photon extraction efficiency.

[0030] In a preferred embodiment of the present invention, the thickness of the transparent oxide shell is 0.1~5 nm, preferably 0.1~2 nm. By precisely controlling the thickness of the transparent oxide shell, an optimal balance between the photoluminescence performance and long-term stability of quantum dots can be achieved. Excessive thickness leads to reduced luminescence intensity, while insufficient thickness fails to provide adequate protection and significantly improve stability.

[0031] In a preferred embodiment of the present invention, the mass percentage of the perovskite quantum dots to the triphenylphosphine oxide ligand is 1 wt% to 30 wt%, preferably 10 wt% to 25 wt%. It should be noted that insufficient TPPO dosage cannot effectively passivate surface defects of the quantum dots and inhibit quantum dot aggregation; excessive TPPO dosage may alter the local dielectric constant and affect luminescence performance.

[0032] This invention provides a method for preparing a pure red perovskite quantum dot luminescent material, comprising the following steps: Step 1: Provide composite nanospheres with ligand-modified quantum dots embedded in the surface channels; In this embodiment, the method for preparing composite nanospheres with ligand-modified quantum dots embedded in surface channels is as follows: a) Preparing nanoporous spheres and ligand-modified quantum dots, wherein the ligand-modified quantum dots include perovskite quantum dots modified with triphenylphosphine oxide ligands; b) The ligand-modified quantum dots are mechanically mixed with nanoporous spheres. The mechanical mixing method can be various, such as mechanical grinding. c) The mixed material is heat-treated to melt the quantum dots and embed them into the surface pores of the nanoporous spheres; the heat treatment can be performed in various ways, such as placing the material in a tube furnace and calcining it at high temperature.

[0033] Step 2: Form a transparent oxide shell on the surface of the composite nanospheres.

[0034] In this embodiment, atomic layer deposition (ALD) is performed on the composite nanospheres to coat their surface with a transparent oxide shell, thereby obtaining the quantum dot luminescent material.

[0035] This method is simple to operate, low in cost, and easy to industrialize. The prepared pure red perovskite quantum dot fluorescent microspheres not only exhibit excellent luminescence performance, but also demonstrate superior luminescence stability under high power density blue light.

[0036] In a preferred embodiment of the present invention, the mass percentage of perovskite quantum dots CsPbI3 to the passivation ligand triphenylphosphine oxide is 1wt% to 30wt%, optionally 10wt% to 25wt%. Optimizing the ratio of CsPbI3 to triphenylphosphine oxide can optimize the luminescence performance of the quantum dots. More preferably, the ratios are 10wt%, 20wt%, and 25wt%.

[0037] In a preferred embodiment of the present invention, the particle size of the nanoporous spheres is 50~250 nm and / or the pore size of the nanoporous spheres is 3~30 nm; In a preferred embodiment of the present invention, the thickness of the transparent oxide shell is 0.1~5 nm, preferably 0.1~2 nm. By precisely controlling the thickness of the transparent oxide shell, an optimal balance between the photoluminescence performance and long-term stability of quantum dots can be achieved. Excessive thickness leads to reduced luminescence intensity, while insufficient thickness fails to provide adequate protection and significantly improve stability.

[0038] The oxides in the transparent oxide shell are aluminum oxide and / or silicon dioxide.

[0039] In some embodiments, the calcination temperature is 400~500℃. More preferably, the calcination temperature is 420℃, 450℃, or 480℃.

[0040] The ligand-modified quantum dots include perovskite quantum dots modified with triphenylphosphine oxide ligands. In the pure red perovskite quantum dot luminescent material provided in this embodiment, the main role of the triphenylphosphine oxide (TPPO) ligand (i) is to react with the Pb on the surface of the CsPbI3 quantum dots. 2+ (ii) Due to its own steric hindrance effect, it can suppress the aggregation of CsPbI3 quantum dots.

[0041] The present invention also provides a red Micro-LED device, comprising the pure red perovskite quantum dot luminescent material as described above, or the pure red perovskite quantum dot luminescent material prepared by the preparation method described above.

[0042] In some embodiments, the red-light Micro-LED device is prepared by fabricating a red light conversion film from the aforementioned pure red perovskite quantum dot fluorescent microspheres, then coating it onto a blue-light Micro-LED array, and tightly bonding them together to form a red-light Micro-LED array. The red light conversion film emits bright red light when excited by the blue-light Micro-LEDs. The blue-light Micro-LEDs have a size of 20 × 20 μm. 2 .

[0043] In some embodiments, the emission peak of the blue Micro-LED is in the range of 450~475 nm; the size of a single Micro-LED is 20×20 μm. 2 The half-width at half maximum (WHM) is less than 20 nm, and the distance between individual Micro-LEDs ranges from 50 to 100 μm.

[0044] In some embodiments, the emission peak of red light is in the range of 620~650 nm, preferably 630 nm; the full width at half maximum (FWHM) is less than 40 nm.

[0045] In some embodiments, the thickness of the red light conversion film is 10~50 μm, preferably 20 μm. When the film thickness is less than 10 μm, the quantum dots do not absorb blue light sufficiently, resulting in blue light leakage and affecting display performance; when the film thickness is greater than 50 μm, the emitted light of the quantum dots is confined within the film, affecting the film's luminous efficiency.

[0046] The following describes embodiments of the present invention. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where the technology or conditions are not specified in the embodiments, they are performed according to the technology or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0047] Example 1 This embodiment provides a method for preparing a pure red perovskite quantum dot luminescent material, including the following steps: (1) Weigh 0.1 mmol cesium iodide (CsI, 0.0260 g), 0.1 mmol lead iodide (PbI2, 0.0461 g), 0.3605 g triphenylphosphine oxide (TPPO), and 0.2163 g mesoporous silica (mSiO2, size 100 nm, mesopores 10 nm) and add them to an agate mortar. Grind with a pestle for 30 min to form a uniformly mixed CsPbI3-TPPO@mSiO2 precursor powder; (2) Pour the precursor powder into an alumina crucible, then place it in a tube furnace, introduce argon gas, raise the temperature to 450°C at a program of 2°C / min, hold for 1 h, and then lower the temperature to 30°C at a program of 5°C / min to obtain CsPbI3-TPPO@mSiO2 nanospheres. (3) Trimethylaluminum (TMA) deposition was performed on CsPbI3-TPPO@mSiO2 nanospheres at 80℃ for two ALD cycles using atomic layer deposition (ALD) technology to obtain a uniform alumina film. Then, bis(diethylamino)silane (BDEAS) deposition was performed at 250℃ for three ALD cycles to construct a dense silicon oxide layer on the surface of the alumina layer, resulting in the final product CsPbI3-TPPO@mSiO2 / AlO x / SiO2 pure red perovskite quantum dot fluorescent microspheres, size 110 nm. Test data for Example 1 can be found in... Figure 1 .

[0048] Example 2 In this embodiment, more triphenylphosphine oxide (TPPO, 0.721 g) was used to replace the triphenylphosphine oxide in Example 1, and the rest of the operation was the same as in Example 1.

[0049] Example 3 In this embodiment, less triphenylphosphine oxide (TPPO, 0.2884 g) was used to replace the triphenylphosphine oxide in Example 1, and the rest of the operation was the same as in Example 1.

[0050] Example 4 In this embodiment, mesoporous silica (mSiO2, size 70 nm, mesopores 3.5 nm) is used to replace the mesoporous silica in Example 1, and the rest of the operation is the same as in Example 1.

[0051] Example 5 In this embodiment, mesoporous silica (mSiO2, size 130 nm, mesopores 14.5 nm) is used to replace the mesoporous silica in Example 1, and the rest of the operation is the same as in Example 1.

[0052] Example 6 In this embodiment, mesoporous silica (mSiO2, size 150 nm, mesopores 20 nm) is used to replace the mesoporous silica in Example 1, and the rest of the operation is the same as in Example 1.

[0053] Example 7 In this embodiment, mesoporous silica (mSiO2, size 200 nm, mesopores 26 nm) is used to replace the mesoporous silica in Example 1, and the rest of the operation is the same as in Example 1.

[0054] Example 8 In this embodiment, the calcination temperature of the CsPbI3-TPPO@mSiO2 precursor powder is reduced to 420°C, and the remaining operations are the same as in Example 1.

[0055] Example 9 In this embodiment, the calcination temperature of the CsPbI3-TPPO@mSiO2 precursor powder is increased to 480°C, and the remaining operations are the same as in Example 1.

[0056] Example 10 In this embodiment, an alumina shell with fewer ALD cycles (1 ALD cycle) is used to replace the alumina shell in Example 1, and the rest of the operation is the same as in Example 1.

[0057] Example 11 In this embodiment, the alumina shell with more ALD cycles (5 ALD cycles) is replaced with the alumina shell of Embodiment 1, and the rest of the operation is the same as in Embodiment 1.

[0058] Example 12 In this embodiment, a silicon oxide shell with fewer ALD cycles (1 ALD cycle) is used to replace the silicon oxide shell in Example 1, and the rest of the operation is the same as in Example 1.

[0059] Example 13 In this embodiment, a silicon oxide shell with more ALD cycles (5 ALD cycles) is used to replace the silicon oxide shell in Example 1, and the rest of the operation is the same as in Example 1.

[0060] Example 14 (1) Add 40 mg CsPbI3-TPPO@mSiO2 / AlO x / SiO2 pure red perovskite quantum dot fluorescent microspheres were dispersed in a mixed solution of 5 ml deionized water and ethylene glycol (volume ratio 3:2), and then filtered through a 0.45 μm polytetrafluoroethylene filter to obtain a uniformly mixed ink. (2) Clean the quartz glass plate with a size of 5 cm × 5 cm with acetone, and then spin coat the photoresist at 600 rpm using a spin coater; (3) Place the glass slide on a heating plate at 120°C and bake for 90 seconds. After the sample cools to room temperature, transfer it to the photolithography machine. (4) Set the exposure energy to 50 mJ / cm 2 To perform ultraviolet exposure; (5) After exposure, immerse the sample in the developer and gently shake for 3 minutes; (6) Rinse with deionized water to remove residual developer and blow dry the sample surface to obtain a micropore array surrounded by a photoresist structure. The ink prepared in step (1) is uniformly filled into the micropore array by spin coating. After the solvent evaporates, the ink solidifies into a film within the micropores, forming a regular array of fluorescent pixels. Under 365 nm ultraviolet irradiation, the array displays a bright red color (see attached image). Figure 7 .

[0061] Example 15 (1) Dissolve 500 mg of polymethyl methacrylate (PMMA) in 1 ml of toluene to form a clear solution, then add 30 mg of CsPbI3-TPPO@mSiO2 / AlO x SiO2 pure red perovskite quantum dot fluorescent microspheres were stirred at 50℃ for 6 h to obtain a uniform slurry. Then, the slurry was scraped onto a glass substrate using an infrared heated flatbed coating machine to form a red light conversion film with a thickness of 5 μm. (2) A red light conversion film is coated on a 4×4 array of blue Micro-LED chips, wherein each blue Micro-LED chip has a size of 20×20 μm.2 ; (3) Under the drive of a 6V DC power supply, the blue Micro-LED array excites the red color conversion film to emit red light. Its electroluminescence spectrum is shown in the appendix. Figure 9 .

[0062] Using the above method, the pure red perovskite quantum dots from Comparative Examples 1-5 and Examples 1-13 were fabricated into red-light Micro-LED devices. The test results are shown in [Figure 1]. Figure 3 .

[0063] Comparative Example 1 This comparative example provides a method for preparing perovskite quantum dot luminescent materials, including the following steps: (1) Weigh 0.1 mmol cesium iodide (CsI, 0.0260 g) and 0.1 mmol lead iodide (PbI2, 0.0461 g) and add them to an agate mortar. Grind with a pestle for 30 min to form a uniformly mixed CsPbI3 precursor powder. (2) Pour the precursor powder into an alumina crucible, then place it in a tube furnace, introduce argon gas, raise the temperature to 450°C at a program of 2°C / min, hold for 1 h, and then lower the temperature to 30°C at a program of 5°C / min to obtain CsPbI3 perovskite quantum dots.

[0064] The difference from Example 1 is that no passivating ligands were added, mesoporous silica was not used, and a transparent oxide shell was not formed; all other operations were the same as in Example 1. Test data for Comparative Example 1 can be found in... Figure 2 .

[0065] Comparative Example 2 This comparative example provides a method for preparing perovskite quantum dot luminescent materials, including the following steps: (1) Weigh 0.1 mmol cesium iodide (CsI, 0.0260 g), 0.1 mmol lead iodide (PbI2, 0.0461 g), and 0.3605 g triphenylphosphine oxide (TPPO) and add them to an agate mortar. Grind with a pestle for 30 min to form a uniformly mixed CsPbI3-TPPO precursor powder. (2) Pour the precursor powder into an alumina crucible, then place it in a tube furnace, introduce argon gas, raise the temperature to 450°C at a program of 2°C / min, hold for 1 h, and then lower the temperature to 30°C at a program of 5°C / min to obtain CsPbI3-TPPO perovskite quantum dots.

[0066] The difference from Example 1 is that mesoporous silica is not used, and a transparent oxide shell is not formed; all other operations are the same as in Example 1. Test data for Comparative Example 2 can be found... Figure 2 .

[0067] Comparative Example 3 This comparative example provides a method for preparing perovskite quantum dot luminescent materials, including the following steps: (1) Weigh 0.1 mmol cesium iodide (CsI, 0.0260 g), 0.1 mmol lead iodide (PbI2, 0.0461 g), 0.3605 g triphenylphosphine oxide (TPPO), and 0.2163 g mesoporous silica (mSiO2, size 100 nm, mesopores 10 nm) and add them to an agate mortar. Grind with a pestle for 30 min to form a uniformly mixed CsPbI3-TPPO@mSiO2 precursor powder; (2) Pour the precursor powder into an alumina crucible, then place it in a tube furnace, introduce argon gas, raise the temperature to 450°C at a program of 2°C / min, hold for 1 h, and then lower the temperature to 30°C at a program of 5°C / min to obtain CsPbI3-TPPO@mSiO2 nanospheres.

[0068] The difference from Example 1 is that no transparent oxide shell is formed; all other operations are the same as in Example 1. Test data for Comparative Example 3 can be found... Figure 2 .

[0069] Comparative Example 4 This comparative example provides a method for preparing perovskite quantum dot luminescent materials, including the following steps: (1) Weigh 0.1 mmol cesium iodide (CsI, 0.0260 g), 0.1 mmol lead iodide (PbI2, 0.0461 g), and 0.3605 g triphenylphosphine oxide (TPPO) and add them to an agate mortar. Grind with a pestle for 30 min to form a uniformly mixed CsPbI3-TPPO precursor powder. (2) Pour the precursor powder into an alumina crucible, then place it in a tube furnace, introduce argon gas, raise the temperature to 450°C at a program of 2°C / min, hold for 1 h, and then lower the temperature to 30°C at a program of 5°C / min to obtain CsPbI3-TPPO perovskite quantum dots. (3) Trimethylaluminum (TMA) deposition was performed on CsPbI3-TPPO perovskite quantum dots at 80 °C for two ALD cycles to obtain a uniform alumina film. Then, bis(diethylamino)silane (BDEAS) deposition was performed at 250 °C for three ALD cycles to construct a dense silicon oxide layer on the surface of the alumina layer, resulting in the final product CsPbI3-TPPO / AlO x / SiO2 pure red perovskite quantum dot fluorescent microspheres.

[0070] The difference from Example 1 is that mesoporous silica is not used; all other operations are the same as in Example 1. Test data for Comparative Example 4 can be found... Figure 2 .

[0071] Comparative Example 5 This comparative example provides a method for preparing perovskite quantum dot luminescent materials, including the following steps: (1) Weigh 0.1 mmol cesium iodide (CsI, 0.0260 g), 0.1 mmol lead iodide (PbI2, 0.0461 g), and 0.2163 g mesoporous silica (mSiO2, size 100 nm, mesopores 10 nm) and add them to an agate mortar. Grind with a pestle for 30 min to form a uniformly mixed CsPbI3@mSiO2 precursor powder; (2) Pour the precursor powder into an alumina crucible, then place it in a tube furnace, introduce argon gas, raise the temperature to 450°C at a program of 2°C / min, hold for 1 h, and then lower the temperature to 30°C at a program of 5°C / min to obtain CsPbI3@mSiO2 nanospheres. (3) Trimethylaluminum (TMA) deposition was performed on CsPbI3@mSiO2 nanospheres at 80℃ for two ALD cycles to obtain a uniform alumina film. Then, bis(diethylamino)silane (BDEAS) deposition was performed at 250℃ for three ALD cycles to construct a dense silicon oxide layer on the surface of the alumina layer, resulting in the final product CsPbI3@mSiO2 / AlO x / SiO2 pure red perovskite quantum dot fluorescent microspheres.

[0072] The difference from Example 1 is that no passivating ligand was added; all other operations were the same as in Example 1. Test data for Comparative Example 5 can be found... Figure 2 .

[0073] The electroluminescence spectrum, brightness, and external quantum efficiency (EQE) test methods are as follows: the electroluminescence spectrum, brightness, and external quantum efficiency of the sample are obtained through a Micro-LED test system.

[0074] The photoluminescence fluorescence spectroscopy test method is as follows: at ambient temperature, the sample is placed in the sample stage, and the photoluminescence fluorescence spectrum and full width at half maximum (FWHM) are obtained by using a fluorescence spectrophotometer (Hitachi, F4600) under ultraviolet light irradiation at a wavelength of 365 nm.

[0075] The fluorescence quantum yield test method is as follows: at ambient temperature, the sample is placed in a fluorescent cuvette and the fluorescence quantum yield (QY) and absorbance (Abs) of the quantum dots are obtained by using an absolute PL quantum yield spectrometer (Hamamatsu, C11347-11) under blue light irradiation at a wavelength of 450 nm.

[0076] T 50 The time required for the sample to reach 50% of its initial luminescence intensity is measured by placing the sample in a constant temperature and humidity incubator at 90% humidity and 60℃.

[0077] The test results can be found here. Figure 2 and Figure 3 .

[0078] Depend on Figure 2 As shown in the table, the blue light absorption rate of Comparative Example 4 is much lower than that of Comparative Example 5. The blue light absorption rate of Example 1 is lower than that of Example 4, but higher than that of Examples 5-7. This indicates that the nanoporous spheres effectively modulate the local light field, improve the blue light absorption rate, and that their particle size and pore size have a significant impact on the modulation effect of the light field. Examples 10-13... 50 Smaller than T in Example 1 and Comparative Example 3 50 The difference in fluorescence quantum yield compared to Example 1 indicates that the transparent oxide shell can effectively mitigate the erosion of perovskite quantum dots by water and oxygen in the environment, but its thickness affects the protective effect. The fluorescence quantum yield of Comparative Example 1 is lower than that of Comparative Example 2, and the fluorescence quantum yields of Examples 2 and 3 are lower than that of Example 1, indicating that an appropriate amount of TPPO can effectively passivate the quantum dot surface and improve the quantum yield. Figure 2 and Figure 3 The data in the table show that the passivated ligands, nanoporous spheres, and transparent oxide shell exert a synergistic effect, thereby greatly improving the luminescence efficiency and luminescence stability of the pure red perovskite quantum dot fluorescent microspheres. Furthermore, Examples 8 and 9, by lowering / raising the calcination temperature of the pure red perovskite quantum dot fluorescent microsphere precursor, respectively, showed performance lower than that of Example 1, indicating that calcination temperature affects the luminescence efficiency and luminescence stability of the pure red perovskite quantum dot fluorescent microspheres.

[0079] Depend on Figure 4-9 As can be seen, the fluorescent pixel array and red Micro-LED device based on pure red perovskite quantum dot fluorescent microspheres prepared in Examples 14 and 15 of this invention not only have high color purity but also ultra-high brightness. Besides applications in the display field, they also play a vital role in fields such as bioimaging, underwater detection, and optical communication.

[0080] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0081] Although this document frequently uses terms such as quantum dots, nanoporous spheres, transparent oxide shells, perovskites, and ligands, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention. The terms "first," "second," etc. (if present), in the specification, claims, and accompanying drawings of the embodiments of the invention, are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pure red perovskite quantum dot light-emitting material, characterized in that, the quantum dot light-emitting material comprises ligand-modified quantum dots, nanometer mesoporous spheres, and a transparent oxide shell layer, wherein the ligand-modified quantum dots are embedded in the surface channels of the nanometer mesoporous spheres to form M@N composite nanospheres, and the transparent oxide shell layer is coated on the surface of the M@N composite nanospheres to form a core-shell structure. The ligand-modified quantum dots comprise perovskite quantum dots modified by triphenylphosphine oxide ligands.

2. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the perovskite quantum dots are CsPbI3.

3. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the particle size of the perovskite quantum dots is 3-20 nm.

4. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the nanometer mesoporous spheres are mesoporous silica.

5. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the particle size of the nanometer mesoporous spheres is 50-250 nm and / or the pore size of the nanometer mesoporous spheres is 3-30 nm.

6. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the oxide in the transparent oxide shell layer is aluminum oxide and / or silicon dioxide.

7. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the thickness of the transparent oxide shell layer is 0.1-5 nm, preferably 0.1-2 nm.

8. The pure red perovskite quantum dot light-emitting material according to claim 1, characterized in that, the mass percentage of the perovskite quantum dots to the triphenylphosphine oxide ligands is 1 wt%-30 wt%, preferably 10 wt%-25 wt%.

9. A preparation method of a pure red perovskite quantum dot light-emitting material, characterized in that, comprising the following steps: providing composite nanospheres with ligand-modified quantum dots embedded in the surface channels thereof; forming a transparent oxide shell layer on the surface of the composite nanospheres; the ligand-modified quantum dots comprise perovskite quantum dots modified by triphenylphosphine oxide ligands.

10. A red Micro-LED device, characterized in that, comprising the pure red perovskite quantum dot light-emitting material according to any one of claims 1-8, or comprising the pure red perovskite quantum dot light-emitting material prepared by the preparation method according to claim 9.

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