Coated perovskite quantum dot material and preparation method thereof

Abstract

The invention discloses a coated perovskite quantum dot material and a preparation method thereof, and belongs to the technical field of quantum dots, modified perovskite quantum dot nanocrystals are coated by aluminum-based MOF, the aluminum-based MOF is taken as a growth site, in-situ growth of iron-based MOF on the surface is realized, the iron-based MOF is partially reduced into nano zero-valent iron by sodium borohydride, and the nano zero-valent iron is prepared. According to the invention, the nano zero-valent iron is added into the perovskite quantum dot, the surface of the perovskite quantum dot is coated with the silicon dioxide layer, the stability of the perovskite quantum dot is improved through three-layer coating, the oxidation degree is reduced, and the nano zero-valent iron can reduce oxidized high-valence ions into low-valence ions, so that the surface defects of the perovskite quantum dot are repaired; a small amount of nano zero-valent iron can be used as a sacrificial point to preferentially react with an oxygen element to generate iron oxide, so that the structural strength of the coating layer can be improved, slow oxidation still occurs when the perovskite quantum dots are used for a long time, lead can form high-valence tetravalent lead due to oxidation, and the nano zero-valent iron has extremely high electron supply capability, so that the performance of the perovskite quantum dots is improved. And dynamic repair can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quantum dots, and particularly relates to a coated perovskite quantum dot material and a preparation method thereof. BACKGROUND

[0002] With the development of science and technology, quantum dot display technology has become one of the most important components of modern optoelectronic products. The popularity and development of optoelectronic products have increasingly high requirements for the display performance, stability and environmental friendliness of materials and many other aspects. Compared with traditional semiconductor quantum dots, lead halide perovskite quantum dots have gradually become a strong competitor in the display field in recent years due to their excellent optical properties, low synthesis cost and environmental friendliness.

[0003] However, the current lead halide perovskite quantum dot material is difficult to maintain good stability under harsh conditions such as humidity, oxygen environment, ultraviolet light and heat atmosphere, which greatly affects the practical application in the display field. In this regard, researchers have made a lot of explorations in improving the stability of quantum dots. Among them, the core-shell structure is considered to be one of the effective means to improve the stability of quantum dots. By coating the quantum dots with a layer, the quantum dots can be isolated from the external environment, which can greatly improve the weather resistance and service life of the quantum dots. In particular, using mesoporous materials to coat the quantum dots, the pre-synthesized mesoporous materials are introduced into the preparation process of perovskite quantum dots, so that the quantum dots are generated in situ in the pores of the mesoporous materials, and then the pores are closed, so that they are protected by the closed shell material and are not affected by the external environment. This method has attracted widespread attention due to its simple synthesis process and uniform product quality. For traditional semiconductor quantum dots, using oxides, polymers and other materials to coat them is a method to improve the stability of quantum dots. A silica shell layer can be used to coat the quantum dots to separate them from the external environment, thereby improving the stability of the quantum dots.

[0004] The current commonly used method for coating silica is to add organic silicate as a precursor to the quantum dot solution. The silica is generated by hydrolysis reaction of air and trace amount of water in the solution and coats the quantum dots in the solution, which can enhance the stability of the quantum dots.

[0005] The Chinese invention patent with the publication number CN114479831B discloses a preparation method of perovskite quantum dot powder. In this scheme, the perovskite quantum dots are coated by porous aluminum oxide. However, the coating layer has a porous structure, so that the perovskite quantum dots will still be slowly oxidized during long-term use, leading to the oxidation of divalent lead ions into tetravalent lead ions, and further leading to the distortion of the crystal structure and the degradation of the function. SUMMARY

[0006] The purpose of the present application is to provide a kind of coated perovskite quantum dot material and preparation method thereof, by aluminum-based MOF to modified perovskite quantum dot nanocrystals are coated, with aluminum-based MOF as growth site, in situ growth iron-based MOF on the surface of aluminum-based MOF coated quantum dot particles, iron-based MOF is reduced into nanometer zero-valent iron using sodium borohydride, and silica layer is coated on the surface, to obtain coated perovskite quantum dot material, the stability of perovskite quantum dot is improved by three-layer coating, the degree of oxidation is reduced, and nanometer zero-valent iron can reduce the high-valence ion oxidized to low-valence state, repair the surface defects of perovskite quantum dot.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] A kind of preparation method of coated perovskite quantum dot material, comprising the following steps:

[0009] Step one: with cesium carbonate as cesium source, lead bromide as lead source, form perovskite crystal nucleus, and the amino group in 2-amino terephthalic acid is coordinated with lead ion, to obtain modified perovskite quantum dot nanocrystals.

[0010] Step two: the carboxyl group of 2-amino terephthalic acid grafted on the surface of modified perovskite quantum dot nanocrystals is coordinated with aluminum ions in N,N-dimethylformamide, to obtain aluminum-based MOF coated quantum dot particles.

[0011] Step three: iron-based MOF is in situ grown on the surface of aluminum-based MOF coated quantum dot particles by hydrothermal synthesis method, to obtain aluminum-iron-based double MOF coated quantum dot particles.

[0012] Step four: through the hydrolysis and polycondensation of gamma-aminopropyl triethoxysilane and methyl silicate, a silica coating layer is formed, and nanometer zero-valent iron is obtained by reducing iron-based MOF into nanometer zero-valent iron using sodium borohydride, to obtain coated perovskite quantum dot material.

[0013] Further, the specific preparation steps of modified perovskite quantum dot nanocrystals are as follows:

[0014] Lead bromide, 1-octadecene and oleic acid are added to the reaction kettle, stirred at 120-130 DEG C and 500-600 r / min under argon atmosphere for 20-30 min, then 2-amino terephthalic acid is added, and then heated to 140-150 DEG C when the solution is clear, continue to stir for 30-40 min, then add cesium oleate precursor solution, continue to react for 5-6 s, quickly cool to room temperature in ice water, to obtain modified perovskite quantum dot nanocrystals.

[0015] Further, the ratio of the use amount of lead bromide, 1-octadecene, oleic acid and 2-amino terephthalic acid is 6-7 g: 400-500 mL: 20-30 mL: 10-20 g: 800-900 mL.

[0016] Further, the specific preparation steps of the cesium oleate precursor solution are as follows:

[0017] The cesium carbonate, oleic acid and 1-octadecene are added to the reaction kettle, stirred at 120-130°C and 500-600 r / min under argon atmosphere for 20-30 min to make the precursor fully dissolved, then heated to 150-160°C, and continue to stir for 30-40 min to obtain the cesium oleate precursor solution.

[0018] Further, the ratio of the use amount of cesium carbonate, oleic acid and 1-octadecene is 20-30 g: 50-60 mL: 800-900 mL.

[0019] Further, the specific preparation steps of the aluminum-based MOF coated quantum dot particles are as follows:

[0020] The modified perovskite quantum dot nanocrystals and N,N-dimethylformamide are added to the reaction kettle lined with polytetrafluoroethylene, stirred at 20-25°C and 500-600 r / min for 20-30 min, then aluminum sulfate octadecahydrate is added, continue to stir for 20-30 min, heated to 120-140°C, continue to stir for 24-26 h, naturally cool to room temperature, filter, the filter cake is washed with N,N-dimethylformamide and methanol for 2-3 times respectively, vacuum dried at 60-80°C for 1-2 h to obtain the aluminum-based MOF coated quantum dot particles.

[0021] Further, the ratio of the use amount of modified perovskite quantum dot nanocrystals, N,N-dimethylformamide and aluminum sulfate octadecahydrate is 80-90 g: 2-3 L: 120-140 g.

[0022] Further, the specific preparation steps of the aluminum-iron-based double MOF coated quantum dot particles are as follows:

[0023] The aluminum-based MOF coated quantum dot particles, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide are added to the reaction kettle lined with polytetrafluoroethylene, stirred at 20-25°C and 500-600 r / min for 20-30 min, then iron chloride and acetic acid solution with a concentration of 1 mol / L are added, ultrasonic dispersion for 40-60 min, heated to 120-140°C, continue to stir for 24-26 h, naturally cool to room temperature, filter, the filter cake is washed with N,N-dimethylformamide and methanol for 2-3 times respectively, vacuum dried at 60-80°C for 1-2 h to obtain the aluminum-iron-based double MOF coated quantum dot particles.

[0024] Further, the use amount ratio of the aluminum-based MOF coated quantum dot particles, 2,5-dihydroxyterephthalic acid, N,N-dimethylformamide, ferric chloride and acetic acid solution is 80-90g:120-140g:3-4L:70-80g:4-5mL.

[0025] Further, the specific preparation steps of the coated perovskite quantum dot material are as follows:

[0026] The aluminum-iron-based double MOF coated quantum dot particles, gamma-aminopropyl triethoxysilane and n-hexane are added into a reaction kettle, stirred at 20-25 DEG C and 500-600r / min for 20-30min, then methyl silicate is added, and stirring is continued for 3-4h, then the mixed solution is added, ultrasonic dispersion is carried out for 40-60min, stirring is continued for 20-30min, 11000-12000r / min centrifugation is carried out for 5-6min, and the precipitate is collected to obtain a coated perovskite quantum dot material.

[0027] Further, the use amount ratio of the aluminum-iron-based double MOF coated quantum dot particles, gamma-aminopropyl triethoxysilane, n-hexane, methyl silicate and the mixed solution is 70-80g:40-50mL:500-600mL:30-40g:7-8mL.

[0028] Further, the mixed solution is obtained by mixing sodium borohydride and an ethanol solution with a mass fraction of 40-50% according to a mass ratio of 1:1.

[0029] The beneficial effects of the present application are as follows:

[0030] 1. The coated perovskite quantum dot material prepared in the present application has good optical performance, high quantum yield and good stability.

[0031] 2. The aluminum-iron-based double MOF coated quantum dot particles in the present application can make the iron-based MOF grow stably and uniformly on the surface of the aluminum-based MOF coated quantum dot particles by the hydrothermal synthesis method, and the spatial confinement effect of the double MOF can improve the stability of the perovskite quantum dots, so that they are not easy to be oxidized and fail in subsequent processing and production.

[0032] 3. The strong reducing property of sodium borohydride can reduce a small amount of trivalent iron ions in the iron-based MOF into nano zero-valent iron and uniformly deposit on the surface of the aluminum-based MOF coated quantum dot particles, avoiding the agglomeration caused by traditional separate addition. Since the standard reduction potential of aluminum is much lower than that of iron, and due to the steric hindrance effect, the aluminum-based MOF coated on the surface of the quantum dot particles will not be destroyed. The Si-O bond energy in the silica coating layer, and silicon is in the highest oxidation state, has no empty orbital to accept electrons, and the reducing property of sodium borohydride is not enough to destroy the Si-O bond, thereby preserving its stable structural properties.

[0033] 4. A small amount of nano zero-valent iron is uniformly dispersed in the coating layer of the perovskite quantum dot. On the one hand, the nano zero-valent iron is not directly loaded on the surface of the perovskite quantum dot, which will not exacerbate the oxidation of the perovskite quantum dot. Secondly, the coating of silicon dioxide can protect the small amount of nano zero-valent iron from being oxidized. A small amount of nano zero-valent iron can act as a sacrificial point to preferentially react with oxygen to form iron oxide, thereby increasing the structural strength of the coating layer. When the perovskite quantum dot is used for a long time, slow oxidation will still occur, and lead will be oxidized to form tetravalent lead. Nano zero-valent iron has strong electron supply capability and can achieve dynamic repair. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0035] Embodiment 1: A preparation method of a coated perovskite quantum dot material, comprising the following steps:

[0036] S1: 20g of cesium carbonate, 50mL of oleic acid and 800mL of 1-octadecene are added to a reaction kettle, stirred at 120℃ and 500r / min for 20min under argon atmosphere, so that the precursor is fully dissolved, then heated to 150℃, and continue to stir for 30min to obtain a cesium oleate precursor solution.

[0037] S2: 6 g of lead bromide, 400 mL of 1-octadecene and 20 mL of oleic acid were added into a reaction kettle, stirred at 120℃ and 500 r / min for 20 min under argon atmosphere, then 10 g of 2-amino terephthalic acid was added, and the solution was clarified, then heated to 140℃, and stirred for 30 min, then 800 mL of cesium oleate precursor solution was added, and the reaction was continued for 5 s, and then quickly cooled to room temperature in ice water to obtain modified perovskite quantum dot nanocrystals.

[0038] Both the amino group and the carboxyl group in 2-amino terephthalic acid have strong coordination ability, but in a non-polar solvent, the coordination of the carboxyl group with lead ions is not conducive, and the reaction time with the cesium oleate precursor solution is only 5 s, which is not enough to form a long-range ordered structure of MOF, so the amino group in 2-amino terephthalic acid is mainly coordinated with lead ions to obtain modified perovskite quantum dot nanocrystals.

[0039] S3: 80 g of modified perovskite quantum dot nanocrystals and 2 L of N,N-dimethylformamide were added into a reaction kettle lined with polytetrafluoroethylene, stirred at 20℃ and 500 r / min for 20 min, then 120 g of aluminum sulfate octadecahydrate was added, and stirred for 20 min, heated to 120℃, and stirred for 24 h, then naturally cooled to room temperature, filtered, and the filter cake was washed with N,N-dimethylformamide and methanol for 2 times respectively, and vacuum dried at 60℃ for 1 h to obtain aluminum-based MOF coated quantum dot particles.

[0040] The 2-amino terephthalic acid grafted in the modified perovskite quantum dot nanocrystals is coordinated with aluminum ions in aluminum sulfate octadecahydrate in N,N-dimethylformamide, and the ordered structure of aluminum-based MOF is hydrothermally synthesized and coated on the surface of perovskite quantum dot nanocrystals.

[0041] S4: 80 g of aluminum-based MOF coated quantum dot particles, 120 g of 2,5-dihydroxy terephthalic acid and 3 L of N,N-dimethylformamide were added into a reaction kettle lined with polytetrafluoroethylene, stirred at 20℃ and 500 r / min for 20 min, then 70 g of iron chloride and 4 mL of acetic acid solution with a concentration of 1 mol / L were added, heated to 120℃, and stirred for 24 h, then naturally cooled to room temperature, filtered, and the filter cake was washed with N,N-dimethylformamide and methanol for 2 times respectively, and vacuum dried at 60℃ for 1 h to obtain aluminum-iron-based double MOF coated quantum dot particles.

[0042] The aluminum-iron-based double MOF coated quantum dot particles were obtained by in-situ growth of iron-based MOF on the surface of aluminum-based MOF coated quantum dot particles by hydrothermal synthesis method.

[0043] S5: 70 g of aluminum-iron-based double MOF coated quantum dot particles, 40 mL of γ-aminopropyl triethoxysilane, and 500 mL of n-hexane were added to a reaction kettle, stirred at 20 ℃ and 500 r / min for 20 min, then 30 g of methyl silicate was added, and stirring was continued for 3 h, then a mixed solution of 7 mL of sodium borohydride and 40% ethanol solution by mass fraction in a mass ratio of 1:1 was added, ultrasonic dispersion was carried out for 40 min, stirring was continued for 20 min, 11000 r / min centrifugation was carried out for 5 min, the precipitate was collected, and a coated perovskite quantum dot material was obtained.

[0044] The γ-aminopropyl triethoxysilane and the methyl silicate hydrolyze and polycondensate to form a silica coating layer, and the strong reducing property of the sodium borohydride can reduce the trivalent iron ions in the iron-based MOF into nano zero-valent iron and uniformly deposit on the surface of the aluminum-based MOF coated quantum dot particles.

[0045] Embodiment 2: A preparation method of a coated perovskite quantum dot material, comprising the following steps:

[0046] S1: 25 g of cesium carbonate, 55 mL of oleic acid, and 850 mL of 1-octadecene were added to a reaction kettle, stirred at 125 ℃ and 550 r / min for 25 min under an argon atmosphere, so that the precursor was fully dissolved, then heated to 155 ℃, and stirring was continued for 35 min to obtain a cesium oleate precursor solution.

[0047] S2: 6.5 g of lead bromide, 450 mL of 1-octadecene, and 25 mL of oleic acid were added to a reaction kettle, stirred at 125 ℃ and 550 r / min for 25 min under an argon atmosphere, then 15 g of 2-amino terephthalic acid was added, and when the solution was clear, it was heated to 145 ℃, and stirring was continued for 35 min, then 800-900 mL of the cesium oleate precursor solution was added, and the reaction was continued for 5.5 s, and then quickly cooled to room temperature in ice water to obtain modified perovskite quantum dot nanocrystals.

[0048] S3: 85 g of modified perovskite quantum dot nanocrystals and 2.5 L of N,N-dimethylformamide were added to a reaction kettle lined with polytetrafluoroethylene, stirred at 22.5 ℃ and 550 r / min for 25 min, then 130 g of aluminum sulfate octadecahydrate was added, stirring was continued for 25 min, heated to 130 ℃, and stirring was continued for 25 h, then naturally cooled to room temperature, filtered, the filter cake was washed with N,N-dimethylformamide and methanol for 2.5 times respectively, and vacuum dried at 70 ℃ for 1.5 h to obtain aluminum-based MOF coated quantum dot particles.

[0049] S4: 85 g of quantum dot particles coated with an aluminum-based MOF, 130 g of 2,5-dihydroxyterephthalic acid, and 3.5 L of N,N-dimethylformamide were added to a reaction kettle lined with polytetrafluoroethylene, stirred at 22.5°C and 550 r / min for 25 min, then 75 g of iron chloride and 4.5 mL of an acetic acid solution with a concentration of 1 mol / L were added, heated to 130°C, and continued to be stirred for 25 h, and then naturally cooled to room temperature, filtered, and the filter cake was washed with N,N-dimethylformamide and methanol for 2.5 times, respectively, and vacuum dried at 70°C for 1.5 h to obtain quantum dot particles coated with an aluminum-iron-based double MOF.

[0050] S5: 75 g of quantum dot particles coated with an aluminum-iron-based double MOF, 45 mL of γ-aminopropyltriethoxysilane, and 550 mL of n-hexane were added to a reaction kettle, stirred at 22.5°C and 550 r / min for 25 min, then 35 g of methyl silicate was added, and continued to be stirred for 3.5 h, then 7.5 mL of sodium borohydride and a 45% mass fraction ethanol solution were added in a mixed solution with a mass ratio of 1:1, ultrasonic dispersion was performed for 50 min, continued to be stirred for 25 min, centrifuged at 11500 r / min for 5.5 min, and the precipitate was collected to obtain a coated perovskite quantum dot material.

[0051] Example 3: A preparation method of a coated perovskite quantum dot material, comprising the following steps:

[0052] S1: 30 g of cesium carbonate, 60 mL of oleic acid, and 900 mL of 1-octadecene were added to a reaction kettle, stirred at 130°C and 600 r / min for 30 min under an argon atmosphere, so that the precursors were fully dissolved, then heated to 160°C, and continued to be stirred for 40 min to obtain a cesium oleate precursor solution.

[0053] S2: 7 g of lead bromide, 500 mL of 1-octadecene, and 30 mL of oleic acid were added to a reaction kettle, stirred at 130°C and 600 r / min for 30 min under an argon atmosphere, then 20 g of 2-amino terephthalic acid was added, and when the solution was clear, it was heated to 150°C and continued to be stirred for 40 min, then 800-900 mL of the cesium oleate precursor solution was added, and continued to be reacted for 6 s, and then quickly cooled to room temperature in ice water to obtain modified perovskite quantum dot nanocrystals.

[0054] S3: 90 g of modified perovskite quantum dot nanocrystals and 4 L of N,N- dimethylformamide were added to a reaction kettle lined with polytetrafluoroethylene, stirred at 25 °C and 600 r / min for 30 min, then 140 g of aluminum sulfate octadecahydrate was added, and stirring was continued for 30 min, heated to 140 °C, and stirring was continued for 26 h, and then naturally cooled to room temperature. The filter cake was washed with N,N-dimethylformamide and methanol for 3 times respectively, and vacuum dried at 80 °C for 2 h to obtain aluminum-based MOF coated quantum dot particles.

[0055] S4: 90 g of aluminum-based MOF coated quantum dot particles, 140 g of 2,5- dihydroxyterephthalic acid and 4 L of N,N-dimethylformamide were added to a reaction kettle lined with polytetrafluoroethylene, stirred at 25 °C and 600 r / min for 30 min, then 80 g of iron chloride and 5 mL of 1 mol / L acetic acid solution were added, heated to 140 °C, and stirring was continued for 26 h, and then naturally cooled to room temperature. The filter cake was washed with N,N-dimethylformamide and methanol for 3 times respectively, and vacuum dried at 80 °C for 2 h to obtain aluminum-iron-based double MOF coated quantum dot particles.

[0056] S5: 80 g of aluminum-iron-based double MOF coated quantum dot particles, 50 mL of γ-aminopropyltriethoxysilane and 600 mL of n-hexane were added to a reaction kettle, stirred at 25 °C and 600 r / min for 30 min, then 40 g of methyl silicate was added, and stirring was continued for 4 h, then 8 mL of sodium borohydride and 50% ethanol solution were added in a mass ratio of 1:1, ultrasonic dispersion was carried out for 60 min, stirring was continued for 30 min, and then centrifugation was carried out at 12000 r / min for 6 min. The precipitate was collected to obtain a coated perovskite quantum dot material.

[0057] Comparative Example 1: On the basis of Example 3, 2-aminoterephthalic acid in step S2 was removed, and perovskite quantum dot nanocrystals were used instead of modified perovskite quantum dot nanocrystals in the original step, and the remaining steps were unchanged to obtain a coated perovskite quantum dot material.

[0058] Comparative Example 2: On the basis of Example 3, the aluminum-iron-based double MOF coated quantum dot particles in step S4 were replaced by the aluminum-based MOF coated quantum dot particles in step S3 without step S4 treatment, and the remaining steps were unchanged to obtain a coated perovskite quantum dot material.

[0059] Comparative Example 3: On the basis of Example 3, the mixture of sodium borohydride and ethanol solution in a mass ratio of 1:1 in step S6 was removed, and the remaining steps were unchanged to obtain a coated perovskite quantum dot material.

[0060] The coated perovskite quantum dot material obtained in Example 1-Example 3 and Comparative Example 1-Comparative Example 3 was subjected to performance testing, and the results are shown in Table 1.

[0061] 1. Photoluminescence (PL) spectrum test: The fluorescence spectrum of the sample was tested by using an Edinburgh Instruments FLS1000 fluorescence spectrometer, and the test conditions were as follows: excitation wavelength was 365 nm, test range was 500 nm, test wavelength was 0.5 nm, and slit was 0.5 nm.

[0062] 2. Quantum yield test: The sample was tested by using an Edinburgh Instruments FLS1000 fluorescence spectrometer and an integral sphere, and the fluorescence quantum yield of the sample was calculated. Before testing, the coated perovskite quantum dot material was diluted with n-hexane, and the concentration of the diluted solution was 10 μg / mL. The same volume of n-hexane solution was used as a reference sample.

[0063] 3. Stability test: The sample to be tested was placed on a heating stage, and the temperature was set to 60°C. The photoluminescence spectrum of the sample to be tested was tested again at 10 min and 30 min after heating to test the thermal stability. The sample solution to be tested was mixed with deionized water at a ratio of 1:1. The photoluminescence spectrum of the sample to be tested was tested again at 10 min and 30 min after mixing to test the water stability.

[0064] Table 1: Performance test results of coated perovskite quantum dot material

[0065]

[0066] As can be seen from Table 1, the photoluminescence intensity and quantum yield of the coated perovskite quantum dot material prepared in Example 1-Example 3 are significantly better than those of the comparative examples. In the stability test, the photoluminescence intensity is still better than that of the comparative examples, indicating that the coated perovskite quantum dot material prepared by the present application has good optical performance, high quantum yield and good stability.

[0067] In Comparative Example 1, 2-amino terephthalic acid was removed, which prevented the growth of aluminum-based MOF and also failed to provide a site for the subsequent generation of iron-based MOF, resulting in a decrease in the stability of the perovskite quantum dots. Moreover, the subsequent sodium borohydride converted a small amount of iron in the iron-based MOF into nano zero-valent iron, which was directly loaded on the surface of the perovskite quantum dots, thereby exacerbating the oxidation of the perovskite quantum dots.

[0068] The aluminum-iron-based double MOF coated quantum dot particles in Comparative Example 2 are replaced by aluminum-based MOF coated quantum dot particles, resulting in the original coating layer changing from three layers to two layers, reducing the stability of the perovskite quantum dots, and also failing to grow nano zero-valent iron to achieve dynamic repair.

[0069] In Comparative Example 3, the mixed solution of sodium borohydride and ethanol with a mass ratio of 1:1 is removed. The sodium borohydride changes a small amount of iron in the iron-based MOF into nano zero-valent iron. A small amount of nano zero-valent iron can act as a sacrificial point, preferentially reacting with oxygen elements to generate iron oxide, thereby increasing the structural strength of the coating layer. During the long-term use of perovskite quantum dots, slow oxidation may still occur, and lead may form tetravalent lead due to oxidation. However, nano zero-valent iron has strong electron supply capability, which can achieve dynamic repair.

[0070] Although embodiments of the present application have been shown and described, it will be understood by those having ordinary skill in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application.

Claims

1. A method for preparing a coated perovskite quantum dot material, characterized in that, Comprising the following steps: Step one: with cesium carbonate as cesium source, lead bromide as lead source, perovskite crystal nucleus is formed, and the amino group in 2-amino terephthalic acid is coordinated with lead ions to obtain modified perovskite quantum dot nanocrystals; Step two: the carboxyl group of 2-amino terephthalic acid grafted on the surface of the modified perovskite quantum dot nanocrystals is coordinated with aluminum ions to obtain aluminum-based MOF coated quantum dot particles; Step three: iron-based MOF is grown in situ on the surface of aluminum-based MOF coated quantum dot particles by hydrothermal synthesis method to obtain aluminum-iron-based double MOF coated quantum dot particles; Step four: a silica coating layer is formed by hydrolysis and polycondensation of gamma-aminopropyl triethoxysilane and methyl silicate, and iron-based MOF is reduced to nano zero-valent iron by sodium borohydride to obtain coated perovskite quantum dot material.

2. The method of claim 1, wherein the method is characterized by: The specific preparation steps of the modified perovskite quantum dot nanocrystals are as follows: Lead bromide, 1-octadecene and oleic acid are added to a reaction kettle, stirred at 120-130℃ and 500-600r / min for 20-30min under argon atmosphere, then 2-amino terephthalic acid is added, and the solution is heated to 140-150℃ when it is clear, then continue to stir for 30-40min, then add cesium oleate precursor solution, continue to react for 5-6s, quickly cool to room temperature in ice water, and obtain modified perovskite quantum dot nanocrystals.

3. The method of claim 2, wherein the method further comprises the step of adding a surfactant to the solution of the perovskite quantum dots. The amount ratio of lead bromide, 1-octadecene, oleic acid and 2-amino terephthalic acid is 6-7g:400-500mL:20-30mL:10-20g:800-900mL.

4. The method of claim 2, wherein the method further comprises the step of adding a surfactant to the solution of the perovskite quantum dots. The specific preparation steps of the cesium oleate precursor solution are as follows: Cesium carbonate, oleic acid and 1-octadecene are added to a reaction kettle, stirred at 120-130℃ and 500-600r / min for 20-30min under argon atmosphere, so that the precursor is fully dissolved, then heated to 150-160℃, continue to stir for 30-40min, and obtain cesium oleate precursor solution; The amount ratio of cesium carbonate, oleic acid and 1-octadecene is 20-30g:50-60mL:800-900mL.

5. The method of claim 1, wherein the method is characterized by: The specific preparation steps of the aluminum-based MOF coated quantum dot particles are as follows: Modified perovskite quantum dot nanocrystals and N,N-dimethylformamide are added to a reaction kettle lined with polytetrafluoroethylene, stirred at 20-25℃ and 500-600r / min for 20-30min, then add aluminum sulfate octadecahydrate, continue to stir for 20-30min, heat to 120-140℃, continue to stir for 24-26h, cool naturally, filter, wash, vacuum dry, and obtain aluminum-based MOF coated quantum dot particles.

6. The method of claim 5, wherein the coating type perovskite quantum dot material is prepared by the following steps of: (1) preparing a perovskite quantum dot material; (2) preparing a coating material; and (3) coating the perovskite quantum dot material with the coating material. The amount ratio of modified perovskite quantum dot nanocrystals, N,N-dimethylformamide and aluminum sulfate octadecahydrate is 80-90g:2-3L:120-140g.

7. The method of claim 1, wherein the method is characterized by: The specific preparation steps of the aluminum-iron-based double MOF coated quantum dot particles are as follows: Aluminum-based MOF coated quantum dot particles, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide are added into a reaction kettle lined with polytetrafluoroethylene, stirred at 20-25℃ and 500-600r / min for 20-30min, then iron chloride and 1mol / L acetic acid solution are added, ultrasonic dispersion is carried out for 40-60min, heated to 120-140℃, continue to stir for 24-26h, natural cooling, filtration, washing, vacuum drying, to obtain aluminum-iron-based double MOF coated quantum dot particles; The aluminum-based MOF coated quantum dot particles, 2,5-dihydroxyterephthalic acid, N,N-dimethylformamide, iron chloride and acetic acid solution are used in a ratio of 80-90g:120-140g:3-4L:70-80g:4-5mL.

8. The method for preparing a coated perovskite quantum dot material according to claim 1, characterized in that, The specific preparation steps of the coated perovskite quantum dot material are as follows: Aluminum-iron-based double MOF coated quantum dot particles, γ-aminopropyl triethoxysilane and n-hexane are added into a reaction kettle, stirred at 20-25℃ and 500-600r / min for 20-30min, then methyl silicate is added, continue to stir for 3-4h, then add the mixed solution, ultrasonic dispersion is carried out for 40-60min, continue to stir for 20-30min, centrifugation at 11000-12000r / min for 5-6min, collect the precipitate, to obtain a coated perovskite quantum dot material; The aluminum-iron-based double MOF coated quantum dot particles, γ-aminopropyl triethoxysilane, n-hexane, methyl silicate and mixed solution are used in a ratio of 70-80g:40-50mL:500-600mL:30-40g:7-8mL.

9. The method of claim 8, wherein the coating is applied by a method selected from the group consisting of spin coating, dip coating, spray coating, and inkjet printing. The mixed solution is obtained by mixing sodium borohydride and 40-50wt% ethanol solution in a mass ratio of 1:

1.

10. A coated perovskite quantum dot material, characterized in that, Prepared by the method of any one of claims 1-9. Prepared by the method of any one of claims 1-9.

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