Preparation method of perovskite quantum dot based on green solvent and application of perovskite quantum dot in white light LED device

Abstract

The invention discloses a preparation method of a perovskite quantum dot based on a green solvent and application of the perovskite quantum dot in a white light LED device, and belongs to the field of quantum dot display. Green macro preparation of efficient and stable perovskite quantum dots is realized by introducing the green solvent in synthesis, optimizing the synthesis method and adopting a room-temperature one-step method; the production cost can be greatly reduced, the production efficiency can be improved, the environment and human health can be protected, and the concept of sustainable development is met. The powder material obtained after drying treatment can be used for manufacturing a white LED with high luminous efficiency, and reliable technical support is provided for commercial application of photoelectric devices.

Description

Technical Field

[0001] The present invention belongs to the field of quantum dot displays, and particularly relates to a preparation method of perovskite quantum dots based on green solvents and their application in white light LED devices. Background Art

[0002] In recent years, all - spectrum inorganic lead halide (CsPbX 3 , X = Cl, Br, I) perovskite quantum dots have shown great application prospects in optoelectronic devices such as solar cells, light - emitting diodes, and lasers due to their simple preparation method, large absorption cross - section, high fluorescence quantum efficiency (PLQY), narrow emission spectrum, and tunable fluorescence emission wavelength.

[0003] However, the research on perovskite quantum dots still faces many challenges. First, the optoelectronic properties and stability of perovskite quantum dots are more easily affected by surface defects and ligands. The traditionally used surface ligands such as oleic acid and oleylamine have limited effects in protecting the stability of quantum dots. The dynamic equilibrium between OA / OAm and the quantum dot surface usually leads to unstable binding on the quantum dot surface, which often causes some ligands to desorb from the quantum dot surface, resulting in poor stability of the quantum dots and the subsequent fabricated LED devices. And there are literatures indicating that the surface of quantum dots passivated by zwitterionic ligands is more stable, the ligands are not easily detached, and it can effectively prevent halogen migration.

[0004] Secondly, the solvents used for preparing quantum dots are mostly toxic and harmful solvents, such as methanol, dimethyl sulfoxide (DMSO), and N,N - dimethylformamide (DMF). These toxic solvents may pose potential hazards to human health and the environment, and improper handling may lead to environmental pollution and ecological damage.

[0005] In addition, in the actual production process, how to achieve large - scale and low - cost preparation of perovskite quantum dots is still an urgent problem to be solved. Traditional synthesis methods for preparing perovskite quantum dots, such as the hot - injection method, although can prepare high - quality quantum dots, but due to the need for high - temperature and high - pressure equipment and precise temperature control, the cost is relatively high, usually applicable to small - batch preparation, and it is difficult to achieve large - scale production.

[0006] In summary, while pursuing high-efficiency luminescence and stability of perovskite quantum dots, how to solve the problem of realizing large-scale production with green solvents and ensure their excellent performance in various practical application scenarios is a key issue that urgently needs to be solved in the current scientific research community. With the continuous advancement of scientific research work, perovskite quantum dots show great development potential in the optoelectronic field, especially in applications such as high-efficiency white LEDs, indicating that they may have more extensive uses in the future. However, the inherent sensitivity of this material makes it extremely vulnerable to external environmental interference, resulting in a significant decline in luminescence efficiency and stability, which undoubtedly poses a considerable obstacle to its practical application. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0008] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0009] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of perovskite quantum dots based on green solvents.

[0010] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of perovskite quantum dots based on green solvents, comprising, Mix cesium carbonate and n-octanoic acid, stir at room temperature, and obtain a cesium carbonate n-octanoic acid mixed solution when the solution is completely transparent; Mix lead acetate trihydrate and n-octanoic acid, stir at room temperature, and obtain a lead acetate trihydrate n-octanoic acid mixed solution when the solution is completely transparent; Mix tetraoctylammonium bromide, n-octanoic acid and the solvent n-hexane, stir at room temperature, and obtain a tetraoctylammonium bromide n-octanoic acid mixed n-hexane solution when the solution is completely transparent; Mix zwitterionic ligands and n-octanoic acid, and obtain a zwitterionic ligand n-octanoic acid mixed solution at room temperature when the solution is completely transparent; Add the tetraoctylammonium bromide n-octanoic acid mixed n-hexane solution and the cesium carbonate n-octanoic acid mixed solution to the zwitterionic ligand n-octanoic acid mixed solution in sequence at room temperature to obtain a precursor; Inject the lead acetate trihydrate n-octanoic acid mixed solution into the precursor for reaction to obtain a zwitterionic ligand-modified perovskite quantum dot stock solution; Add a centrifuging agent to the stock solution of perovskite quantum dots modified with zwitterionic ligands, centrifuge to obtain a precipitate, and place the precipitate in a vacuum drying oven for drying to obtain pure perovskite quantum dot phosphor.

[0011] As a preferred embodiment of the preparation method of the present invention, wherein: in the cesium carbonate and n-octanoic acid mixed solution, the molar ratio of cesium carbonate to n-octanoic acid is 16:1.

[0012] As a preferred embodiment of the preparation method of the present invention, wherein: in the lead acetate trihydrate and n-octanoic acid mixed solution, the molar ratio of lead acetate trihydrate to n-octanoic acid is 16:1.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: in the tetraoctylammonium bromide, n-octanoic acid and n-hexane mixed solution, the molar ratio of tetraoctylammonium bromide to n-octanoic acid is 40:1.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: in the zwitterionic ligand and n-octanoic acid mixed solution, the molar ratio of the zwitterionic ligand to n-octanoic acid is 7:1.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the volume ratio of the cesium carbonate and n-octanoic acid mixed solution, the lead acetate trihydrate and n-octanoic acid mixed solution, the zwitterionic ligand and n-octanoic acid mixed solution, and the tetraoctylammonium bromide, n-octanoic acid and n-hexane mixed solution is 1:1:1:14.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: the centrifuging agent includes acetone, and the volume ratio of the centrifuging agent to the stock solution of perovskite quantum dots is 2:1.

[0017] Another object of the present invention is to overcome the deficiencies in the prior art and provide a perovskite quantum dot, the average size of the perovskite quantum dot is 7-9 nm, and the fluorescence emission peak is 510-515 nm.

[0018] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of titanium perovskite quantum dots in the preparation of white light LED devices, including, After drying the perovskite quantum dots into a powder form, mix them evenly with yellow and red phosphors, and then incorporate them into the organic encapsulating silica gel; Among them, the organic encapsulating silica gel includes silica gel A and silica gel B, the volume ratio of silica gel A to silica gel B is 1:3, and the mass ratio of the perovskite quantum dot phosphor, the yellow phosphor and the red phosphor is 6:4:1; Using a 450 nm blue light LED chip as an excitation source, drop-coat the above mixture onto it to fabricate a perovskite quantum dot white light LED device based on a green solvent system.

[0019] Advantages of the present invention: (1) By introducing a green solvent in the synthesis and optimizing the synthesis method, the present invention realizes the green macroscale preparation of highly efficient and stable perovskite quantum dots through a one-step method at room temperature, which can greatly reduce the production cost, improve the production efficiency, contribute to environmental protection and human health, and conform to the concept of sustainable development. (2) By introducing zwitterionic ligands, the ripening process of perovskite quantum dots is effectively inhibited, and the size growth of quantum dots is successfully controlled; the zwitterionic ligands can bind more tightly to the surface of perovskite quantum dots, effectively passivate surface defects, significantly enhance the stability of quantum dots, and improve their optical properties, thereby realizing highly efficient and stable luminescence. The powder material obtained after drying treatment can be used to fabricate high-efficiency white LEDs, providing reliable technical support for the commercial application of optoelectronic devices. Description of the drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them: Figure 1 Fluorescence emission spectrum of lecithin-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 2 Ultraviolet absorption spectrum of lecithin-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 3 X-ray diffraction pattern of lecithin-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 4 Transmission electron microscope image of lecithin-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 5 Storage stability diagram of lecithin-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 6 Fluorescence emission spectrum of lecithin-modified CsPbBr perovskite quantum dots in toluene and n-hexane solvents prepared in Example 1 of the present invention; 3 Figure 7This is a device structure diagram of a white light emitting LED chip prepared in large quantities according to Example 2 of the present invention; Figure 8 This is a spectrum diagram of the white light LED prepared in large quantities according to Example 2 of the present invention; Figure 9 This is the color coordinate diagram of the white light LED prepared in large quantities according to Example 2 of the present invention.

[0021] Figure 10 It is the fluorescence emission spectrum of the product prepared in Comparative Example 1 of the present invention.

[0022] Figure 11 This is a comparison chart of thermal stability in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0026] In the embodiments of the present invention, organic silica gel A (organic silica gel ZWL8820H A; Shenzhen looking longtechnology co., LTD); organic silica gel B (organic silica gel ZWL8820H B; Shenzhen looking longtechnology co., LTD), and other raw materials are also common commercially available products.

[0027] Example 1 (1) Mix 1 mmol of cesium carbonate and 10 mL of octanoic acid and stir at room temperature for 30 min. When the solution becomes completely transparent, a cesium carbonate-octanoic acid mixed solution is obtained.

[0028] (2) Mix 1 mmol of lead acetate trihydrate and 10 mL of octanoic acid and stir at room temperature for 1 h. When the solution is completely transparent, a mixed solution of lead acetate trihydrate and octanoic acid is obtained.

[0029] (3) Mix 12 mmol of tetraoctylammonium bromide with 50 mL of n - caprylic acid and 100 mL of the solvent n - hexane, stir for 30 min at room temperature, and obtain a mixed n - hexane solution of tetraoctylammonium bromide and n - caprylic acid when the solution becomes completely transparent.

[0030] (4) Mix 2 mmol of lecithin with 50 mL of n - caprylic acid, stir for 30 min at room temperature, and obtain a mixed solution of zwitterionic ligand and n - caprylic acid when the solution becomes completely transparent.

[0031] (5) Add 135 mL of the mixed n - hexane solution of tetraoctylammonium bromide and n - caprylic acid and 10 mL of the mixed solution of cesium carbonate and n - caprylic acid to the mixed solution of zwitterionic ligand and n - caprylic acid in sequence, stir for 5 min at room temperature to obtain the final precursor; Inject 10 mL of the mixed solution of lead acetate trihydrate and n - caprylic acid into the above - mentioned precursor and react for 2 min to obtain a stock solution of perovskite quantum dots modified with zwitterionic ligand.

[0032] (6) Add the obtained stock solution of quantum dots to a centrifuge tube and simultaneously add acetone with twice the volume of the stock solution, centrifuge at a speed of 10000 r / min for two minutes. After centrifugation, pour off the supernatant and add 100 mL of n - hexane to the precipitate. Shake the centrifuge tube, and after the precipitate is completely dissolved, centrifuge at a speed of 8000 r / min for two minutes. The obtained supernatant is the pure green - emitting CsPbBr 3 perovskite quantum dot product.

[0033] (7) Replace the n - hexane solvent with an equal amount of toluene, repeat the above steps, and obtain CsPbBr synthesized using n - hexane and toluene as solvents and modified with zwitterionic ligand 3 perovskite quantum dot product.

[0034] As Figure 1 shown is the fluorescence emission spectrum of perovskite quantum dots modified with lecithin, and its emission wavelength is at 510 nm.

[0035] As Figure 2 shown is the ultraviolet absorption spectrum of perovskite quantum dots modified with lecithin, and its absorption peak coincides with the fluorescence emission spectrum.

[0036] As Figure 3 shown is the X - ray diffraction pattern of perovskite quantum dots modified with lecithin, which shows a high crystallinity of the sample and indicates that the sample is a standard monoclinic perovskite crystal.

[0037] As Figure 4 shown is the transmission electron microscope image of perovskite quantum dots modified with lecithin, and its average size is about 7.6 nm, and the size is relatively uniform.

[0038] To test the stability of the product, the product was stored indoors and the change in luminescence intensity was tested. Specifically, 2 mL of the prepared quantum dot solution was taken in a cuvette and placed in the integrating sphere sample chamber to test its photoluminescence (PL) intensity. Subsequently, the test sample was collected in a glass bottle and stored indoors to test the change in its PL intensity. As Figure 5 shown, after 60 days of storage, the luminescence intensity can still be maintained at about 80% of the initial intensity.

[0039] Using equal volumes of n - hexane and toluene as solvents, perovskite quantum dots were prepared by the same method (the method in Example 1), and the prepared quantum dot solutions were respectively placed in the integrating sphere sample chamber to test their photoluminescence intensities. As Figure 6 shown, the PL intensity diagrams of the perovskite quantum dots prepared with n - hexane and toluene as solvent assistants under lecithin modification are presented. It shows that when n - hexane is used as the solvent to prepare quantum dots, the PL intensity of the sample is effectively improved compared to the toluene solvent.

[0040] Example 2 (1) 500 mmol of cesium carbonate and 5000 mL of n - octanoic acid were mixed and stirred at room temperature for 30 min. When the solution became completely transparent, a cesium carbonate - n - octanoic acid mixed solution was obtained.

[0041] (2) 500 mmol of lead(II) acetate trihydrate and 5000 mL of n - octanoic acid were mixed and stirred at room temperature for 1 h. When the solution became completely transparent, a lead(II) acetate trihydrate - n - octanoic acid mixed solution was obtained.

[0042] (3) 6000 mmol of tetra - n - octylammonium bromide, 25000 mL of n - octanoic acid and 50000 mL of the solvent n - hexane were mixed and stirred at room temperature for 30 min. When the solution became completely transparent, a tetra - n - octylammonium bromide - n - octanoic acid mixed n - hexane solution was obtained.

[0043] (4) 1000 mmol of lecithin and 25000 mL of n - octanoic acid were mixed and stirred at room temperature for 30 min. When the solution became completely transparent, an amphiphilic ligand - n - octanoic acid mixed solution was obtained.

[0044] (5) 67500 mL of the tetra - n - octylammonium bromide - n - octanoic acid mixed n - hexane solution and 5000 mL of the cesium carbonate - n - octanoic acid mixed solution were successively added to the amphiphilic ligand - n - octanoic acid mixed solution and stirred at room temperature for 5 min to obtain the final precursor. 5000 mL of the lead(II) acetate trihydrate - n - octanoic acid mixed solution was injected into the above - mentioned precursor and reacted for 2 min to obtain the amphiphilic ligand - modified perovskite quantum dot stock solution.

[0045] (6) Add the obtained quantum dot stock solution into a centrifuge tube, and simultaneously add acetone with a volume twice that of the stock solution. Centrifuge at a speed of 10,000 r / min for two minutes. After centrifugation, pour off the supernatant. Place the precipitate in a vacuum drying oven and dry at 40 °C for 24 h to obtain pure green-emitting CsPbBr 3 perovskite quantum dot phosphor.

[0046] (7) Thoroughly stir 50 mg of silicone A and 150 mg of silicone B. Then add 60 mg of green perovskite quantum dot phosphor, 40 mg of Y 3 Al 5 O 12 :Ce yellow phosphor and 10 mg of CaAlSiN 3 :Eu red phosphor into the mixed AB glue and stir well.

[0047] Apply the mixed phosphor-containing organic AB glue onto a 450 nm blue LED chip, and anneal at 100 °C for one hour to solidify the organic encapsulating silicone, obtaining a high-performance white light-emitting LED chip. The device structure of the chip is as Figure 7 shown. Among them, the blue LED serves as an excitation light source to excite the phosphor mixed coating to emit light, and white light is emitted through combination.

[0048] As Figure 8 shown is the spectral diagram of the prepared white LED. It can be seen the emission peak of the blue chip (442 nm) and the emission peak of the green quantum dot phosphor (510 nm).

[0049] As Figure 9 shown is the chromaticity coordinate diagram of the prepared white LED, and its chromaticity coordinate value is (0.34, 0.34).

[0050] Comparative Example 1 Keep (1), (2), (4), and (6) in Example 1 unchanged, and only change (3) and (5) in Example 1 as follows: I. n(Lecithin):n(OTAC)=1:1 (3) Mix 12 mmol of tetraoctylammonium bromide, 318 mL of n-octanoic acid, and 100 mL of the solvent n-hexane, and stir at room temperature for 30 min. When the solution becomes completely transparent, obtain a tetraoctylammonium bromide - n-octanoic acid - mixed n-hexane solution; (5) Add 376 mL of the tetraoctylammonium bromide - n-octanoic acid - mixed n-hexane solution and 10 mL of the cesium carbonate - n-octanoic acid mixed solution into the zwitterionic ligand - n-octanoic acid mixed solution in sequence, and stir at room temperature for 5 min to obtain the final precursor.

[0051] II. n(Lecithin):n(OTAC) = 3:1 (3)Mix 12 mmol of tetraoctylammonium bromide, 106 mL of octanoic acid, and 100 mL of the solvent n - hexane, and stir for 30 min at room temperature. When the solution becomes completely transparent, a mixed n - hexane solution of tetraoctylammonium bromide and octanoic acid is obtained; (5)Sequentially add 185 mL of the mixed n - hexane solution of tetraoctylammonium bromide and octanoic acid and 10 mL of the mixed solution of cesium carbonate and octanoic acid to the mixed solution of zwitterionic ligand and octanoic acid, and stir for 5 min at room temperature to obtain the final precursor.

[0052] III. n(Lecithin):n(OTAC) = 5:1 (3)Mix 12 mmol of tetraoctylammonium bromide, 64 mL of octanoic acid, and 100 mL of the solvent n - hexane, and stir for 30 min at room temperature. When the solution becomes completely transparent, a mixed n - hexane solution of tetraoctylammonium bromide and octanoic acid is obtained; (5)Sequentially add 148 mL of the mixed n - hexane solution of tetraoctylammonium bromide and octanoic acid and 10 mL of the mixed solution of cesium carbonate and octanoic acid to the mixed solution of zwitterionic ligand and octanoic acid, and stir for 5 min at room temperature to obtain the final precursor.

[0053] IV. n(Lecithin):n(OTAC) = 7:1 (3)Mix 12 mmol of tetraoctylammonium bromide, 50 mL of octanoic acid, and 100 mL of the solvent n - hexane, and stir for 30 min at room temperature. When the solution becomes completely transparent, a mixed n - hexane solution of tetraoctylammonium bromide and octanoic acid is obtained; (5)Sequentially add 135 mL of the mixed n - hexane solution of tetraoctylammonium bromide and octanoic acid and 10 mL of the mixed solution of cesium carbonate and octanoic acid to the mixed solution of zwitterionic ligand and octanoic acid, and stir for 5 min at room temperature to obtain the final precursor.

[0054] The results are shown in Figure 10 , when the molar ratio of the zwitterionic ligand to octanoic acid ranges from 1:1 to 7:1, it can be seen that the PL intensity is the highest at 7:1.

[0055] Comparative Example 2 Place the perovskite quantum dot solutions prepared with n - hexane and toluene solvents respectively in an integrating sphere, and measure their PLQYs before heating (PLQY at 0 min). Subsequently, raise the heating plate to 70 °C, place the two kinds of quantum dots on the heating plate, and measure their PLQYs every 10 min to obtain the thermal stability data of the two kinds of quantum dots.

[0056] After normalizing the data and plotting it in the form of a dot-line graph, we obtain Figure 11 . It can be seen from the graph that the perovskite quantum dot solution prepared with n-hexane solvent has better thermal stability.

[0057] 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 preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing perovskite quantum dots based on green solvents, characterized in that: include, Mixing cesium carbonate and n-octanoic acid, stirring at room temperature, and obtaining a cesium carbonate n-octanoic acid mixed solution when the solution is completely transparent; Mixing lead acetate trihydrate and n-octanoic acid, stirring at room temperature, and obtaining a lead acetate trihydrate n-octanoic acid mixed solution when the solution is completely transparent; Mixing tetra-n-octylammonium bromide and n-octylic acid with a solvent, n-hexane, and stirring at room temperature until the solution is completely transparent to obtain a tetra-n-octylammonium bromide n-octylic acid mixed n-hexane solution; Mixing the zwitterionic ligand and n-octanoic acid, and obtaining a zwitterionic ligand n-octanoic acid mixed solution at room temperature when the solution is completely transparent; The precursor is obtained by sequentially adding tetra-n-octylammonium bromide n-octanoic acid mixed n-hexane solution and cesium carbonate n-octanoic acid mixed solution to the zwitterionic ligand n-octanoic acid mixed solution at room temperature; Injecting a mixed solution of lead acetate trihydrate and n-octanoic acid into the precursor for reaction to obtain a zwitterionic ligand-modified perovskite quantum dot stock solution; The centrifugal agent is added into the zwitterionic ligand modified perovskite quantum dot stock solution, the precipitate is obtained by centrifugation, and the precipitate is placed in a vacuum drying oven to be dried to obtain pure perovskite quantum dot phosphor.

2. The preparation method according to claim 1, characterized in that: The cesium carbonate-octanoic acid mixed solution has a molar ratio of cesium carbonate to octanoic acid of 16:

1.

3. The preparation method according to claim 1 or 2, characterized in that: The lead acetate trihydrate and n-octanoic acid mixed solution, wherein the molar ratio of lead acetate trihydrate and n-octanoic acid is 16:

1.

4. The preparation method according to claim 3, characterized in that: The tetra-n-octylammonium bromide and n-octylic acid are mixed with n-hexane solution, wherein the molar ratio of the tetra-n-octylammonium bromide and n-octylic acid is 40:

1.

5. The preparation method according to claim 4, characterized in that: The zwitterionic ligand n-octanoic acid mixed solution, wherein the molar ratio of the zwitterionic ligand to n-octanoic acid is 7:

1.

6. The preparation method according to claim 1, characterized in that: The volume ratio of the cesium carbonate n-octanoic acid mixed solution, the lead acetate trihydrate n-octanoic acid mixed solution, the zwitterionic ligand n-octanoic acid mixed solution and the tetra-n-octylammonium bromide n-octanoic acid mixed n-hexane solution is 1:1:1:

14.

7. The preparation method according to claim 1 or 6, characterized in that: The centrifugal agent includes acetone, and the volume ratio of the centrifugal agent to the perovskite quantum dot stock solution is 2:

1.

8. The perovskite quantum dots prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The average size of the perovskite quantum dots is 7-9 nm, and the fluorescence emission peak is 510-515 nm.

9. Use of the perovskite quantum dots according to claim 8 in the preparation of white light LED devices.

10. The use according to claim 9, characterized in that: include, After the perovskite quantum dots are dried into powder, they are evenly mixed with yellow and red phosphors and then incorporated into organic encapsulation silica gel; The organic encapsulation silica gel includes silica gel A and silica gel B, the volume ratio of silica gel A to silica gel B is 1:3, and the mass ratio of perovskite quantum dot phosphor, yellow phosphor and red phosphor is 6:4:1; A 450 nm blue LED chip was used as the excitation light source, and the above mixture was drop-coated on it to produce a perovskite quantum dot white light LED device based on a green solvent system.

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