A high-temperature resistant metal halide perovskite quantum dot and preparation method thereof

Abstract

The present invention belongs to the field of perovskite quantum dots, and specifically relates to a high-temperature resistant metal halide perovskite quantum dot and a preparation method thereof. The present invention is based on the thermal stability problem of metal halide perovskite quantum dots, and focuses on solving the problem that its crystal structure is prone to collapse and severe fluorescence quenching occurs in a high-temperature environment. Existing technologies mostly use polymers (such as PMMA, PVDF) and mesoporous materials (such as molecular sieves and porous alumina) to physically protect perovskite quantum dots in order to isolate them from contact with external water and oxygen. However, the above technologies cannot solve the stability of perovskite quantum dots in a high-temperature environment. The present invention can well solve the thermal stability of metal halide perovskite quantum dots, and can still maintain 100% fluorescence brightness in an environment of 250 degrees Celsius, and only 3% of the fluorescence brightness decays after continuous testing for one month in this environment.

Description

Technical Field

[0001] The present invention belongs to the field of perovskite quantum dots, and in particular relates to high-temperature resistant metal halide perovskite quantum dots and a preparation method thereof. Background Art

[0002] As the primary medium for information presentation and a fundamental window for human-computer interaction, new display technologies have become one of the most important optoelectronic applications developed today. Liquid crystal display (LCD) technology dominates the display market due to its mature process and low cost. Quantum dots (QDs), as an ideal luminescent material for wide-color-gamut LCDs, have attracted widespread attention. Compared to traditional rare-earth-doped phosphors, QDs offer higher PLQY, narrower full-width at half maximum (FWHM), and tunable band gaps, extending the display color gamut from 70% to 130% of NTSC.

[0003] Metal halide perovskites of CsPbX3 (X = Cl, Br, I) are considered promising next-generation luminescent materials due to their ionic properties, high photoluminescence quantum yield (PLQY), narrow emission peak half-width, and tunable emission spectra. However, current metal halide perovskite quantum dots (QDs) suffer from very poor thermal stability. They are prone to rapid fluorescence quenching and crystal structure decomposition at elevated temperatures (above 100°C), limiting their large-scale industrial application.

[0004] The existing method of protecting metal halide perovskite quantum dots is by embedding them in solid polymers and mesoporous materials. However, although the above strategies can greatly improve their stability, their thermal stability is still insufficient (fluorescence is severely attenuated under 200°C test). At present, the industry uses upper and lower double barrier films to wrap perovskite quantum dots to enhance their stability, but the stability can only meet the aging standard of 60°C, and cannot reach the commercial standard of 85°C. More importantly, the cost of the barrier layer is half of the total price of the quantum dot light-emitting film, which greatly hinders its commercial application. Summary of the Invention

[0005] The existing method of protecting metal halide perovskite quantum dots is to embed them in solid polymers and mesoporous materials. However, although the above strategies can greatly improve their stability, their thermal stability is still insufficient (fluorescence shows severe attenuation under 200°C test). At present, the industry uses upper and lower double barrier films to wrap perovskite quantum dots to enhance their stability, but the stability can only meet the aging standard of 60°C, and cannot reach the commercial standard of 85°C. More importantly, the cost of the barrier layer accounts for half of the total price of PQDF, which greatly hinders its commercial application.

[0006] None of the above methods can perfectly protect perovskite quantum dots, which will still decompose and experience fluorescence quenching in high-temperature heating environments.

[0007] In order to solve the above-mentioned technical problems, this application provides the following technical solutions:

[0008] The present invention provides a method for preparing high-temperature resistant metal halide perovskite quantum dots, comprising the following steps:

[0009] (1) adding lead bromide to an aqueous solution containing a metal salt to obtain a mixed solution A;

[0010] (2) adding cesium bromide to the mixed solution A and mixing to obtain a mixed solution B;

[0011] (3) adding silica nanoparticles to the mixed solution B, stirring, filtering, and drying to obtain quantum dot powder;

[0012] (4) Using a vapor deposition method, fluorine-containing silane is coated on the surface of the quantum dot powder to obtain the high-temperature resistant metal halide perovskite quantum dots.

[0013] Preferably, the metal salt is selected from potassium bromide, calcium chloride or sodium thiosulfate.

[0014] Preferably, the fluorine-containing silane is selected from perfluoroheptadecantrimethylsilane.

[0015] Preferably, in step (2), the mixing method is ultrasonic dissolution for 20-40 minutes.

[0016] Preferably, the mass ratio of the lead bromide to the metal salt is 54-56:750.

[0017] Preferably, the mass ratio of lead bromide to cesium bromide is 27-28:16.

[0018] Preferably, the mass ratio of the lead bromide to the silicon dioxide nanoparticles is 54-56:1.

[0019] Preferably, the lead bromide and fluorine-containing silane are added in a ratio of 540-560 mg to 0.4-0.6 mL.

[0020] Preferably, in step (3), the drying method is to heat and dry the mixture in an oven at 65-75°C.

[0021] Preferably, in step (4), the vapor deposition time is 0.8-1.2 h.

[0022] The present invention also provides high-temperature resistant metal halide perovskite quantum dots prepared by the above preparation method.

[0023] This invention addresses the thermal stability of metal halide perovskite quantum dots, specifically addressing the problem of their crystal structure collapsing and severe fluorescence quenching at high temperatures. Existing technologies often use polymers (such as polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF)) and mesoporous materials to physically protect perovskite quantum dots from water and oxygen. However, these technologies fail to address the stability of perovskite quantum dots at high temperatures.

[0024] The technical solution of the present invention has the following advantages over the prior art:

[0025] The present invention can effectively solve the thermal stability problem of metal halide perovskite quantum dots, and can maintain 100% fluorescence brightness in an environment of 250 degrees Celsius. Moreover, the fluorescence brightness decays by only 3% after continuous testing for one month in this environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flow chart of the preparation method of high-temperature resistant metal halide perovskite quantum dots provided in Example 1 of the present invention.

[0027] Figure 2 Schematic diagram of the preparation process of high-temperature resistant metal halide perovskite quantum dots provided in Example 1 of the present invention.

[0028] Figure 3 Scanning electron microscopy image of silica nanoparticles.

[0029] Figure 4 This is a scanning electron microscope image of silica nanoparticles loaded with quantum dots.

[0030] Figure 5 This is a transmission electron microscope image of silica-loaded quantum dots.

[0031] Figure 6 This is a photo of the quantum dot powder of Example 1.

[0032] Figure 7 This is a graph showing the thermal stability of quantum dots at 250°C in Example 1. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0034] Example 1

[0035] S10: Add 7500 mg of potassium bromide to 15 mL of deionized water and dissolve by ultrasonication for 30 minutes to obtain a potassium bromide aqueous solution; S20: Dissolve 550.5 mg of lead bromide in the potassium bromide aqueous solution;

[0036] S30: Add 320 mg of cesium bromide to the solution of lead bromide and potassium bromide and sonicate for 30 minutes to dissolve;

[0037] S40: adding 10 g of silica nanoparticles to the solution in the above step;

[0038] S50: mixing and stirring the liquids in the above steps;

[0039] S60: filtering the mixed solution, leaving the precipitate at the bottom, and drying to obtain quantum dot powder;

[0040] In this embodiment, the precipitate was placed in an oven at 70°C for heating and drying;

[0041] S70: coating the dried quantum dot powder obtained in S60 with fluorine-containing silane using a vapor deposition method;

[0042] In this embodiment, the specific method of the vapor deposition method is to add 0.5 mL of fluorinated silane perfluoroheptadecanotrimethylsilane and then stir in air for one hour;

[0043] S80: After stirring is completed, a powder of fluorinated silane-coated silica-loaded quantum dots is obtained.

[0044] Example 2

[0045] S10: 7500 mg of calcium chloride was added to 15 mL of deionized water and dissolved by ultrasonication for 20 minutes to obtain a calcium chloride aqueous solution; S20: 550.5 mg of lead bromide was dissolved in the calcium chloride aqueous solution;

[0046] S30: Add 320 mg of cesium bromide to the solution of lead bromide and calcium chloride and sonicate for 20 minutes to dissolve;

[0047] S40: adding 10 g of silica nanoparticles to the solution in the above step;

[0048] S50: mixing and stirring the liquids in the above steps;

[0049] S60: filtering the mixed solution, leaving the precipitate at the bottom, and drying to obtain quantum dot powder;

[0050] In this embodiment, the precipitate was placed in an oven at 65°C for heating and drying;

[0051] S70: coating the dried quantum dot powder obtained in S60 with fluorine-containing silane using a vapor deposition method;

[0052] In this embodiment, the specific method of the vapor deposition method is to add 0.5 mL of fluorinated silane perfluoroheptadecanotrimethylsilane and then stir in air for 0.8 h;

[0053] S80: After stirring is completed, a powder of fluorinated silane-coated silica-loaded quantum dots is obtained.

[0054] Example 3

[0055] S10: 7500 mg of sodium thiosulfate was added to 15 mL of deionized water and dissolved by ultrasonication for 40 minutes to obtain a sodium thiosulfate aqueous solution;

[0056] S20: Dissolve 550.5 mg of lead bromide in an aqueous solution of sodium thiosulfate;

[0057] S30: Add 320 mg of cesium bromide to the solution of lead bromide and sodium thiosulfate and sonicate for 40 minutes to dissolve;

[0058] S40: adding 10 g of silica nanoparticles to the solution in the above step;

[0059] S50: mixing and stirring the liquids in the above steps;

[0060] S60: filtering the mixed solution, leaving the precipitate at the bottom, and drying to obtain quantum dot powder;

[0061] In this embodiment, the precipitate was placed in an oven at 75°C for heating and drying;

[0062] S70: coating the dried quantum dot powder obtained in S60 with fluorine-containing silane using a vapor deposition method;

[0063] In this embodiment, the specific method of the vapor deposition method is to add 0.5 mL of fluorinated silane perfluoroheptadecanotrimethylsilane and then stir in air for 1.2 hours;

[0064] S80: After stirring is completed, a powder of fluorinated silane-coated silica-loaded quantum dots is obtained.

[0065] Effect evaluation 1

[0066] Figure 5 In the experiment, the transmission electron microscopy test results proved that the scheme successfully prepared the metal salt layer and fluorine-containing silane to coat the perovskite quantum dots.

[0067] The quantum dot powder synthesized in Example 1 can still show good fluorescence properties when heated at 250°C.

[0068] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing high-temperature resistant metal halide perovskite quantum dots, characterized in that: The steps include: (1) adding lead bromide to an aqueous solution containing a metal salt to obtain a mixed solution A; (2) adding cesium bromide to the mixed solution A and mixing to obtain a mixed solution B; (3) adding silica nanoparticles to the mixed solution B, stirring, filtering, and drying to obtain quantum dot powder; (4) Using a vapor deposition method, fluorine-containing silane is coated on the surface of the quantum dot powder to obtain the high-temperature resistant metal halide perovskite quantum dots; in the step (3), the drying method is heating and drying in an oven at 65-75°C; in the step (4), the vapor deposition time is 0.8-1.2 h.

2. The preparation method according to claim 1, wherein The metal salt is selected from potassium bromide, calcium chloride or sodium thiosulfate.

3. The preparation method according to claim 1, wherein The fluorine-containing silane is selected from perfluoroheptadecantrimethylsilane.

4. The preparation method according to claim 1, wherein In the step (2), the mixing method is ultrasonic dissolution for 20-40 minutes.

5. The preparation method according to claim 1, wherein The mass ratio of the lead bromide to the metal salt is 54-56:

750.

6. The preparation method according to claim 1, wherein The mass ratio of the lead bromide to the cesium bromide is 27-28:

16.

7. The preparation method according to claim 1, wherein The mass ratio of the lead bromide to the silicon dioxide nanoparticles is 54-56:

1.

8. A high-temperature resistant metal halide perovskite quantum dot prepared by the preparation method according to any one of claims 1 to 7.

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