MOF / perovskite quantum dot composite material and preparation method thereof

Abstract

The invention discloses an MOF / perovskite quantum dot composite material and a preparation method thereof, and belongs to the technical field of composite materials. The preparation method comprises the following steps: grinding and mixing quartz sand, boric oxide, sodium carbonate, nano zirconium dioxide, cesium bromide and lead bromide, carrying out glass fusion packaging to obtain zirconium-based perovskite quantum dot powder, treating the zirconium-based perovskite quantum dot powder by using a silane coupling agent, grafting europium / terbium MOF to obtain zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder, and drying the zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder. The preparation method comprises the following steps: preparing zirconium-based perovskite quantum dot-grafted europium / terbium-MOF powder, dispersing the zirconium-based perovskite quantum dot-grafted europium / terbium-MOF powder in methylbenzene, adding tetramethoxysilane, ammonia water and absolute ethyl alcohol for hydrolysis coating, and modifying by using a 2H-perfluorodecyl triethoxy silane solution to obtain the MOF / perovskite quantum dot composite material, so that the stability and fluorescence quantum yield of the perovskite quantum dot material are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a MOF / perovskite quantum dot composite material and a preparation method thereof. Background Art

[0002] Perovskite quantum dot composites are a class of composite materials containing perovskite quantum dots and other materials (such as iron oxide and organosilicon). These materials combine the properties of perovskite quantum dots and other components, exhibiting versatility and potential application value. MOF / perovskite quantum dot composites combine perovskite quantum dots with metal-organic frameworks (MOFs). These composites combine the excellent optoelectronic properties of perovskite quantum dots with the high specific surface area, porous structure, and excellent stability of MOFs.

[0003] Perovskite quantum dots, with their high light absorption coefficient, narrow-band emission, tunable band gap, and high quantum yield, are commonly used in light-emitting diodes (LEDs) and photovoltaic devices. MOFs, on the other hand, provide a large number of active sites, with adjustable structure and functionalization, making them widely used in catalysis and sensing. Combining the two can improve catalytic activity and enhance the efficiency of photocatalytic reactions. By combining the functions of both, the composite material has a wider range of applications in sensing, energy storage, and other fields.

[0004] The Chinese invention patent application with publication number CN115849436A discloses a graphene / Zr-BDC MOF / perovskite quantum dot high thermal conductivity composite material and its preparation method. The Zr-BDC MOF metal-organic framework material is used to form a stable framework structure, and the perovskite quantum dots are compounded into the interior of the framework structure to improve the service life. The perovskite quantum dots are compounded with graphene on the surface of the Zr-BDC MOF metal-organic framework material to improve the electrical conductivity and thermal conductivity coefficient. However, perovskite quantum dots are extremely sensitive to water. If they are not hydrophobic treated, they may cause stability problems such as narrowing of the color gamut, uneven brightness, and accelerated light decay in display technology, affecting the material performance and service life. Summary of the Invention

[0005] The purpose of the present invention is to provide a MOF / perovskite quantum dot composite material and a preparation method thereof, so as to solve the stability problems of perovskite quantum dots, such as easy water absorption and instability, which may cause color gamut narrowing, uneven brightness, accelerated light decay, etc. in display technology.

[0006] The present invention adds zirconium dioxide when preparing perovskite quantum dots, melts them at high temperature and performs glass encapsulation to form a rigid protective layer, then uses the silane coupling agent KH550 to modify the surface and graft rare earth europium / terbium MOF. The surface of the quantum dots is passivated through the coordination effect of europium / terbium-MOF, thereby enhancing the fluorescence quantum yield and strengthening the interface bonding, making the perovskite quantum dots highly luminescent and easy to disperse. The silicon dioxide shell layer generated by the hydrolysis of tetramethoxysilane and the hydrophobic modification of perfluorosilane are then combined to improve the moisture and heat resistance and oxidation resistance of the perovskite quantum dots.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A method for preparing a MOF / perovskite quantum dot composite material comprises the following steps:

[0009] Step 1: Grind and mix quartz sand, boron oxide, sodium carbonate, nano zirconium dioxide, cesium bromide and lead bromide, melt at high temperature, anneal, crystallize, grind and sieve to obtain zirconium-based perovskite quantum dot powder.

[0010] Step 2: Treat the zirconium-based perovskite quantum dot powder with a silane coupling agent KH550 ethanol solution, vacuum dry it, and then react it with a europium / terbium MOF precursor solution. Wash and dry it to obtain a zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder.

[0011] Step 3: Using tetramethoxysilane as the silicon source, nano-silica is formed by the sol-gel method and zirconium-based perovskite quantum dots are grafted with europium / terbium-MOF powder to be coated, and then modified with 2H-perfluorodecyltriethoxysilane solution to obtain a MOF / perovskite quantum dot composite material.

[0012] Furthermore, a MOF / perovskite quantum dot composite material is prepared by the following steps:

[0013] Zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder and toluene were added to a reactor and stirred evenly. Tetramethoxysilane, 28wt% ammonia water and anhydrous ethanol were then added dropwise. The mixture was stirred for 4-5 hours and centrifuged at 8000 rpm for 3-5 minutes. The precipitate was collected and transferred to a 1wt% 2H-perfluorodecyltriethoxysilane solution. After soaking for 1-2 hours, the mixture was vacuum dried at 50°C for 6-7 hours to obtain a MOF / perovskite quantum dot composite material.

[0014] Furthermore, the dosage ratio of zirconium-based perovskite quantum dots grafted europium / terbium-MOF powder, toluene, tetramethoxysilane, ammonia water, anhydrous ethanol and 2H-perfluorodecyltriethoxysilane solution is 20-30 g: 200-250 mL: 1.2-1.4 mL: 0.5-0.9 mL: 200-250 mL: 100-120 mL.

[0015] Furthermore, the zirconium-based perovskite quantum dots grafted europium / terbium-MOF powder is specifically prepared by the following steps:

[0016] Zirconium-based perovskite quantum dot powder and 5wt% silane coupling agent KH550 ethanol solution are added to a reactor, soaked for 30-40 minutes, filtered, and the filter cake is transferred to an oven and vacuum dried at 60°C for 1-2 hours to obtain modified zirconium-based perovskite quantum dot powder; modified zirconium-based perovskite quantum dot powder and europium / terbium MOF precursor solution are added to a reactor, reacted at 100°C for 12-14 hours, filtered, and the product is washed with ethanol 3-5 times and vacuum dried at 60°C to obtain zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder.

[0017] Furthermore, the dosage ratio of zirconium-based perovskite quantum dot powder, silane coupling agent KH550 ethanol solution, modified zirconium-based perovskite quantum dot powder and europium / terbium MOF precursor solution is 80-100 g: 100-120 mL: 80-100 g: 100-120 mL.

[0018] Furthermore, the zirconium-based perovskite quantum dot powder is prepared by the following steps:

[0019] Quartz sand, boron oxide, sodium carbonate, nano zirconium dioxide, cesium bromide and lead bromide passed through a 150-mesh sieve are added to a reactor, ground for 15-25 minutes, and mixed evenly to obtain a mixed powder; the mixed powder is added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 60-70 minutes, taken out and transferred to a copper plate mold preheated to 360°C, annealed for 10-12 hours, heated to 470°C, crystallized for 10-12 hours, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

[0020] Furthermore, the mass ratio of quartz sand, boron oxide, sodium carbonate, nano zirconium dioxide, cesium bromide, lead bromide and mixed powder is 20-30:28-38:20-30:8-18:38-48:66-76:150-180.

[0021] Furthermore, the europium / terbium MOF precursor solution is prepared by the following steps:

[0022] Europium nitrate hexahydrate, terbium nitrate hexahydrate, trimesic acid, N,N-dimethylamide and anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a europium / terbium MOF precursor solution.

[0023] Furthermore, the usage ratio of europium nitrate hexahydrate, terbium nitrate hexahydrate, trimesic acid, N,N-dimethylamide and anhydrous ethanol is 0.223-0.227 g: 0.227-0.231 g: 0.105-0.109 g: 50-60 mL: 50-60 mL.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention improves the environmental stability of perovskite quantum dots by adding zirconium dioxide during the preparation of perovskite quantum dots, melting them at high temperature and then encapsulating them in glass to form a rigid protective layer. The surface of the perovskite quantum dots is then modified with a silane coupling agent KH550 and grafted with rare earth europium / terbium MOF. The surface of the quantum dots is passivated through the coordination of europium / terbium-MOF, thereby enhancing the fluorescence quantum yield and strengthening the interface bonding, making them highly luminescent and easy to disperse. Furthermore, the silicon dioxide shell layer generated by the hydrolysis of tetramethoxysilane and the hydrophobic modification of perfluorosilane are combined to further improve the moisture and heat resistance and oxidation resistance of the perovskite quantum dots.

[0026] 2. The present invention combines zirconium doping with molten glass technology to prepare perovskite quantum dots, completely encapsulating the perovskite quantum dots in a rigid glass matrix with a high melting point and high chemical inertness. The addition of zirconium significantly enhances the chemical durability and mechanical strength of the glass, and improves the perovskite quantum dots' resistance to high temperatures, water and oxygen erosion, and chemical corrosion.

[0027] 3. The europium and terbium in the europium / terbium-MOF of the present invention serve as highly efficient luminescent rare earth ions. After the quantum dots absorb light, they transfer energy to the adjacent rare earth ions, exciting them to emit light, thereby generating light with a wavelength different from that of the quantum dots themselves, forming multi-color luminescence with better luminescence performance and quantum yield. Grafting the europium / terbium MOF onto the surface of the perovskite quantum dots can act as a physical coating, providing a protective shell for the quantum dots to isolate them from water and oxygen erosion in some environments. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Example 1: A method for preparing a MOF / perovskite quantum dot composite material, comprising the following steps:

[0030] S1: 0.223 g of europium nitrate hexahydrate, 0.105 g of trimesic acid, 10 mL of N,N-dimethylformamide, and 2.5 mL of anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a europium MOF precursor solution.

[0031] S2: 20g of quartz sand passed through a 150-mesh sieve, 28g of boron oxide, 20g of sodium carbonate, 8g of nano-zirconium dioxide, 38g of cesium bromide and 66g of lead bromide were added to a reactor, ground for 15min, and mixed evenly to obtain a mixed powder; 150g of the mixed powder prepared above was added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 60min, taken out and transferred to a copper plate mold preheated to 360°C in advance, annealed for 10h, heated to 470°C, crystallized for 10h, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

[0032] S3: Add 80g of zirconium-based perovskite quantum dot powder and 100mL of 5% mass concentration of silane coupling agent KH550 ethanol solution into the reactor, soak for 30min, filter, transfer the filter cake to an oven, and vacuum dry at 60°C for 1h to obtain modified zirconium-based perovskite quantum dot powder; add 80g of modified zirconium-based perovskite quantum dot powder and 100mL of europium MOF precursor solution into the reactor, react at 100°C for 12h, filter, wash the product with ethanol 3 times, and vacuum dry at 60°C to obtain zirconium-based perovskite quantum dot grafted europium MOF powder.

[0033] S4: Add 20g of zirconium-based perovskite quantum dots grafted europium MOF powder and 200mL of toluene into the reactor and stir evenly to obtain a toluene dispersion of zirconium-based perovskite quantum dots grafted europium MOF powder. Then add 1.2mL of tetramethoxysilane, 0.5mL of 28% ammonia water and 200mL of anhydrous ethanol, stir for 4h, centrifuge at 8000rpm for 3min, collect the precipitate and transfer it to 100mL of 1% 2H-perfluorodecyltriethoxysilane solution, soak for 1h, and vacuum dry at 50°C for 6h to obtain a MOF / perovskite quantum dot composite material.

[0034] Example 2: A method for preparing a MOF / perovskite quantum dot composite material, comprising the following steps:

[0035] S1: 0.227 g of terbium nitrate hexahydrate, 0.105 g of trimesic acid, 10 mL of N,N-dimethylformamide, and 5 mL of anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a terbium MOF precursor solution.

[0036] S2: 20g of quartz sand passed through a 150-mesh sieve, 28g of boron oxide, 20g of sodium carbonate, 8g of nano-zirconium dioxide, 38g of cesium bromide and 66g of lead bromide were added to a reactor, ground for 15min, and mixed evenly to obtain a mixed powder; 150g of the mixed powder prepared above was added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 60min, taken out and transferred to a copper plate mold preheated to 360°C in advance, annealed for 10h, heated to 470°C, crystallized for 10h, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

[0037] S3: Add 80g of zirconium-based perovskite quantum dot powder and 100mL of 5% mass concentration of silane coupling agent KH550 ethanol solution into the reactor, soak for 30min, filter, transfer the filter cake to an oven, and vacuum dry at 60°C for 1h to obtain modified zirconium-based perovskite quantum dot powder; add 80g of modified zirconium-based perovskite quantum dot powder and 100mL of terbium MOF precursor solution into the reactor, react at 100°C for 12h, filter, wash the product with ethanol 3 times, and vacuum dry at 60°C to obtain zirconium-based perovskite quantum dot grafted terbium MOF powder.

[0038] S4: Add 20g of zirconium-based perovskite quantum dot grafted terbium MOF powder and 200mL of toluene into the reactor and stir evenly to obtain a toluene dispersion of zirconium-based perovskite quantum dot grafted terbium MOF powder. Then add 1.2mL of tetramethoxysilane, 0.5mL of 28% ammonia water and 200mL of anhydrous ethanol, stir for 4h, centrifuge at 8000rpm for 3min, collect the precipitate and transfer it to 100mL of 1% 2H-perfluorodecyltriethoxysilane solution, soak for 1h, and vacuum dry at 50°C for 6h to obtain a MOF / perovskite quantum dot composite material.

[0039] Example 3: A method for preparing a MOF / perovskite quantum dot composite material, comprising the following steps:

[0040] S1: 0.223 g of europium nitrate hexahydrate, 0.227 g of terbium nitrate hexahydrate, 0.105 g of trimesic acid, 50 mL of N,N-dimethylformamide, and 50 mL of anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a europium / terbium MOF precursor solution.

[0041] S2: 20g of quartz sand passed through a 150-mesh sieve, 28g of boron oxide, 20g of sodium carbonate, 8g of nano-zirconium dioxide, 38g of cesium bromide and 66g of lead bromide were added to a reactor, ground for 15min, and mixed evenly to obtain a mixed powder; 150g of the mixed powder was added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 60min, taken out and transferred to a copper plate mold preheated to 360°C in advance, annealed for 10h, heated to 470°C, crystallized for 10h, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

[0042] S3: Add 80g of zirconium-based perovskite quantum dot powder and 100mL of 5% mass concentration of silane coupling agent KH550 ethanol solution into the reactor, soak for 30min, filter, transfer the filter cake to an oven, and vacuum dry at 60°C for 1h to obtain modified zirconium-based perovskite quantum dot powder; add 80g of modified zirconium-based perovskite quantum dot powder and 100mL of europium / terbium MOF precursor solution into the reactor, react at 100°C for 12h, filter, wash the product with ethanol 3 times, and vacuum dry at 60°C to obtain zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder.

[0043] S4: Add 20g of zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder and 200mL of toluene into the reactor, stir evenly, then add 1.2mL of tetramethoxysilane, 0.5mL of 28% ammonia water and 200mL of anhydrous ethanol, stir for 4h, centrifuge at 8000rpm for 3min, collect the precipitate and transfer it to 100mL of 1% 2H-perfluorodecyltriethoxysilane solution, soak for 1h, and vacuum dry at 50°C for 6h to obtain a MOF / perovskite quantum dot composite material.

[0044] Example 4: A method for preparing a MOF / perovskite quantum dot composite material, comprising the following steps:

[0045] S1: 0.225 g of europium nitrate hexahydrate, 0.229 g of terbium nitrate hexahydrate, 0.107 g of trimesic acid, 55 mL of N,N-dimethylformamide, and 55 mL of anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a europium / terbium MOF precursor solution.

[0046] S2: 25g of quartz sand passed through a 150-mesh sieve, 33g of boron oxide, 25g of sodium carbonate, 13g of nano-zirconium dioxide, 43g of cesium bromide and 71g of lead bromide were added to a reactor, ground for 20min, and mixed evenly to obtain a mixed powder; 165g of the mixed powder was added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 65min, taken out and transferred to a copper plate mold preheated to 360°C in advance, annealed for 11h, heated to 470°C, crystallized for 11h, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

[0047] S3: Add 90g of zirconium-based perovskite quantum dot powder and 110mL of 5% mass concentration of silane coupling agent KH550 ethanol solution into the reactor, soak for 35min, filter, transfer the filter cake to an oven, and vacuum dry at 60°C for 1.5h to obtain modified zirconium-based perovskite quantum dot powder; add 90g of modified zirconium-based perovskite quantum dot powder and 110mL of europium / terbium MOF precursor solution into the reactor, react at 100°C for 13h, filter, wash the product with ethanol 4 times, and vacuum dry at 60°C to obtain zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder.

[0048] S4: Add 25g of zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder and 225mL of toluene into the reactor, stir evenly, then add 1.3mL of tetramethoxysilane, 0.7mL of 28% ammonia water and 225mL of anhydrous ethanol, stir for 4.5h, centrifuge at 8000rpm for 4min, collect the precipitate and transfer it to 110mL of 1% 2H-perfluorodecyltriethoxysilane solution, soak for 1.5h, and vacuum dry at 50°C for 6.5h to obtain a MOF / perovskite quantum dot composite material.

[0049] Example 5: A method for preparing a MOF / perovskite quantum dot composite material, comprising the following steps:

[0050] S1: 0.227 g of europium nitrate hexahydrate, 0.231 g of terbium nitrate hexahydrate, 0.109 g of trimesic acid, 60 mL of N,N-dimethylformamide, and 60 mL of anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a europium / terbium MOF precursor solution.

[0051] S2: 30g of quartz sand passed through a 150-mesh sieve, 38g of boron oxide, 30g of sodium carbonate, 18g of nano-zirconium dioxide, 48g of cesium bromide and 76g of lead bromide were added to a reactor, ground for 25min, and mixed evenly to obtain a mixed powder; 180g of the mixed powder was added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 70min, taken out and transferred to a copper plate mold preheated to 360°C in advance, annealed for 12h, heated to 470°C, crystallized for 12h, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

[0052] Using a melt-quench-annealing process, the glass matrix melts at high temperature to form a homogeneous solution, which then cools to form a supersaturated solid solution. Annealing relaxes the glass structure, and further heating causes the lead bromide and cesium bromide to diffuse and aggregate, precipitating perovskite nanocrystals on the nucleation sites of zirconium dioxide. Zirconium dioxide acts as a heterogeneous nucleating agent, enhancing the mechanical strength and chemical stability of the glass and reducing quantum dot leakage. The glass encapsulation isolates water and oxygen, addressing the perovskite quantum dot's decomposition issues.

[0053] S3: Add 100g of zirconium-based perovskite quantum dot powder and 120mL of 5% mass concentration of silane coupling agent KH550 ethanol solution into the reactor, soak for 40min, filter, transfer the filter cake to an oven, and vacuum dry at 60°C for 2h to obtain modified zirconium-based perovskite quantum dot powder; add 100g of modified zirconium-based perovskite quantum dot powder and 120mL of europium / terbium MOF precursor solution into the reactor, react at 100°C for 14h, filter, wash the product with ethanol 5 times, and vacuum dry at 60°C to obtain zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder.

[0054] The surface of the quantum dot glass was modified using the silane coupling agent KH550 to introduce coordinating amino groups onto its surface. Then, europium / terbium metal MOFs were grown in situ through coordination bonds to achieve chemical grafting. Europium and terbium are rare earth elements. When they are in the same MOF structure, the color tunability of the dual-wavelength emission is improved, and the MOF coating layer provides a hydrophobic barrier, further increasing the stability in water, oxygen, and light environments. The strong connection formed by silane coupling and MOF coordination bonds reduces quantum dot agglomeration.

[0055] S4: 30 g of zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder and 250 mL of toluene were added to the reactor and stirred evenly. 1.4 mL of tetramethoxysilane, 0.9 mL of 28% ammonia water and 250 mL of anhydrous ethanol were then added dropwise. The mixture was stirred for 5 h and centrifuged at 8000 rpm for 5 min. The precipitate was collected and transferred to 120 mL of 1% 2H-perfluorodecyltriethoxysilane solution. After soaking for 2 h, the mixture was vacuum dried at 50 ° C for 7 h to obtain a MOF / perovskite quantum dot composite material.

[0056] A dense silica layer is constructed on the powder surface through the sol-gel method, and then a perfluoroalkyl chain is added to achieve superhydrophobic protection. The dense silica layer physically blocks environmental erosion, and the perfluoroalkyl chain achieves chemical hydrophobicity, thereby improving the stability of the MOF / perovskite quantum dot composite material in a humid environment.

[0057] The boron oxide described in Examples 1 to 5 was selected from HC-B2O3 of Qinghe Huichu Welding Materials Co., Ltd.; sodium carbonate was selected from Tianjin Zhonghe Shengtai Chemical Co., Ltd. JUHEWU; nano zirconium dioxide was selected from Zhengzhou Jinshui District Honglu Chemical Products Store 1688; and the remaining raw materials were all commercially available products.

[0058] Comparative Example 1: The difference from Example 3 is that in step S1, zinc nitrate hexahydrate is used to replace europium nitrate hexahydrate and terbium nitrate hexahydrate to obtain a zinc MOF precursor solution, and the other steps remain unchanged to prepare a MOF / perovskite quantum dot composite material.

[0059] Comparative Example 2: The difference from Example 3 is that quartz sand, boron oxide, sodium carbonate and nano zirconium dioxide are not added in step S2, and the other steps remain unchanged to prepare a MOF / perovskite quantum dot composite material.

[0060] Comparative Example 3: The difference from Example 3 is that step S4 is not performed, and the remaining steps remain unchanged to prepare a MOF / perovskite quantum dot composite material.

[0061] For Examples 1 to 5 and Comparative Examples 1 to 3, the prepared MOF / perovskite quantum dot composite materials were uniformly mixed with a photocurable resin at a mass ratio of 1:40, degassed using a vacuum degassing machine, and then coated onto a barrier film to a thickness of 150 μm. The films were cured for 1 minute using a 150 W, 365 nm UV lamp to obtain test films. The films were then aged in a constant temperature and humidity chamber at 95% humidity and 65° C., and the time it took for the brightness to decrease by 10% (T90) was recorded to evaluate their resistance to wet heat aging. The quantum yields of different quantum dot composites were tested at an excitation wavelength of 365 nm using an Edinburgh FLS1000 steady-state transient fluorescence spectrometer with an integrating sphere accessory. 2 μL of ultrapure water was added to the surface, and a high-speed camera was used to record the droplet morphology and automatically calculate the contact angle θ. The hydrophobicity test was performed, and the results are shown in Table 1.

[0062] Table 1: Performance test results of MOF / perovskite quantum dot composite materials

[0063] project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Resistance to heat and humidity aging / h 587 592 606 595 584 560 410 570 Quantum yield / % 91 89 93 95 96 70 75 78 Contact angle θ / ° 159 160 170 166 162 155 158 95

[0064] As can be seen from Table 1, the performance of the MOF / perovskite quantum dot composite materials prepared in Examples 1 to 5 of the present invention is significantly better than that of the comparative example; the perovskite quantum dots are glass encapsulated, grafted with rare earth MOFs, and then coated with silica, and the surface is hydrophobicized, which improves the stability and fluorescence quantum yield of the perovskite quantum dot material in terms of physical isolation, chemical stability, and surface hydrophobicity.

[0065] The quantum yield of the quantum dot composite material in Comparative Example 1 decreased significantly, probably because the europium / terbium MOF has better luminescence performance and quantum yield than the zinc MOF. Europium emits red light and terbium emits green light, which can be used to adjust the luminescence color of the composite material and improve the luminescence efficiency; and the porous structure of MOF can also provide a larger specific surface area, which may help stabilize the quantum dots and prevent agglomeration.

[0066] The quantum dot composite material in Comparative Example 2 exhibits significantly poor resistance to wet-heat aging, likely due to the lack of zirconium dioxide and the lack of a molten glass process. The addition of zirconium improves the stability of the glass network, as zirconium ions enhance the mechanical strength and chemical durability of the glass. Melting at 1500°C and then annealing to form a glass encapsulation structure effectively isolates moisture and oxygen, addressing the perovskite quantum dot degradation issue. The glass matrix can also withstand high temperatures, enhancing the material's thermal stability.

[0067] The contact angle of the test film in Comparative Example 3 is significantly smaller, which may be because the silica coating and surface hydrophobic treatment are not performed. The silica is coated with tetramethoxysilane, and the silica layer provides a physical barrier, enhancing its moisture-proof ability, while the perfluorosilane treatment can reduce its surface energy, achieve a hydrophobic effect, and prevent water molecules from entering. This shows that the multi-layer protective structure of the quantum dot composite material in Examples 1 to 5 can significantly improve the service life of the quantum dots.

[0068] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a MOF / perovskite quantum dot composite material, characterized in that: The steps include: Step 1: Grind and mix quartz sand, boron oxide, sodium carbonate, nano zirconium dioxide, cesium bromide and lead bromide, melt at high temperature, anneal, crystallize, grind and sieve to obtain zirconium-based perovskite quantum dot powder; Step 2: Treat the zirconium-based perovskite quantum dot powder with a silane coupling agent KH550 ethanol solution, vacuum dry it, and react it with a europium / terbium MOF precursor solution. Wash and dry it to obtain a zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder. Step 3: Using tetramethoxysilane as the silicon source, nano-silica is formed by the sol-gel method and zirconium-based perovskite quantum dots are grafted with europium / terbium-MOF powder to be coated, and then modified with 2H-perfluorodecyltriethoxysilane solution to obtain a MOF / perovskite quantum dot composite material.

2. The method for preparing a MOF / perovskite quantum dot composite material according to claim 1, characterized in that: The MOF / perovskite quantum dot composite material described in step 3 is specifically prepared by the following steps: Zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder and toluene were added to the reactor and stirred evenly. Tetramethoxysilane, 28wt% ammonia water and anhydrous ethanol were then added dropwise. The mixture was stirred for 4-5h and centrifuged at 8000rpm for 3-5min. The precipitate was collected and transferred to a 1wt% 2H-perfluorodecyltriethoxysilane solution. After soaking for 1-2h, the mixture was vacuum dried at 50°C for 6-7h to obtain a MOF / perovskite quantum dot composite material.

3. The method for preparing a MOF / perovskite quantum dot composite material according to claim 2, characterized in that: The dosage ratio of the zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder, toluene, tetramethoxysilane, ammonia water, anhydrous ethanol and 2H-perfluorodecyltriethoxysilane solution is 20-30 g: 200-250 mL: 1.2-1.4 mL: 0.5-0.9 mL: 200-250 mL: 100-120 mL.

4. The method for preparing a MOF / perovskite quantum dot composite material according to claim 1, characterized in that: The zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder in step 2 is specifically prepared by the following steps: Zirconium-based perovskite quantum dot powder and 5wt% silane coupling agent KH550 ethanol solution are added to a reactor, soaked for 30-40 minutes, filtered, and the filter cake is transferred to an oven and vacuum dried at 60°C for 1-2 hours to obtain modified zirconium-based perovskite quantum dot powder; modified zirconium-based perovskite quantum dot powder and europium / terbium MOF precursor solution are added to a reactor, reacted at 100°C for 12-14 hours, filtered, and the product is washed with ethanol 3-5 times and vacuum dried at 60°C to obtain zirconium-based perovskite quantum dot grafted europium / terbium-MOF powder.

5. The method for preparing a MOF / perovskite quantum dot composite material according to claim 4, characterized in that: The dosage ratio of the zirconium-based perovskite quantum dot powder, the silane coupling agent KH550 ethanol solution, the modified zirconium-based perovskite quantum dot powder and the europium / terbium MOF precursor solution is 80-100 g: 100-120 mL: 80-100 g: 100-120 mL.

6. The method for preparing a MOF / perovskite quantum dot composite material according to claim 5, characterized in that: The zirconium-based perovskite quantum dot powder is specifically prepared by the following steps: Quartz sand, boron oxide, sodium carbonate, nano zirconium dioxide, cesium bromide and lead bromide passed through a 150-mesh sieve are added to a reactor, ground for 15-25 minutes, and mixed evenly to obtain a mixed powder; the mixed powder is added to an alumina crucible, transferred to a muffle furnace, melted at 1500°C for 60-70 minutes, taken out and transferred to a copper plate mold preheated to 360°C, annealed for 10-12 hours, heated to 470°C, crystallized for 10-12 hours, ground, and passed through a 500-mesh sieve to obtain zirconium-based perovskite quantum dot powder.

7. The method for preparing a MOF / perovskite quantum dot composite material according to claim 6, characterized in that: The mass ratio of the quartz sand, boron oxide, sodium carbonate, nano zirconium dioxide, cesium bromide, lead bromide and mixed powder is 20-30:28-38:20-30:8-18:38-48:66-76:150-180.

8. The method for preparing a MOF / perovskite quantum dot composite material according to claim 4, characterized in that: The europium / terbium MOF precursor solution is specifically prepared by the following steps: Europium nitrate hexahydrate, terbium nitrate hexahydrate, trimesic acid, N,N-dimethylamide and anhydrous ethanol were added to a reactor and ultrasonicated until transparent to obtain a europium / terbium MOF precursor solution.

9. The method for preparing a MOF / perovskite quantum dot composite material according to claim 8, characterized in that: The usage ratio of the europium nitrate hexahydrate, the terbium nitrate hexahydrate, trimesic acid, N,N-dimethylamide and anhydrous ethanol is 0.223-0.227 g: 0.227-0.231 g: 0.105-0.109 g: 50-60 mL: 50-60 mL.

10. A MOF / perovskite quantum dot composite material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.