Preparation method and application of perovskite quantum dot based on zinc fluoride double-shell engineering passivation

Abstract

The invention discloses a preparation method and application of perovskite quantum dots based on zinc fluoride double-shell engineering passivation, and the preparation method comprises the following steps: mixing a cesium carbonate n-caprylic acid mixed solution and an n-caprylic acid solution to obtain a cesium carbonate mixed solution; adding the cesium carbonate mixed solution into the lead bromide-tetra-n-octyl ammonium bromide toluene mixed solution, and stirring at room temperature to obtain a precursor; injecting a didodecyl dimethyl ammonium bromide toluene solution into the precursor for reaction, and then injecting a zinc fluoride-tetra-n-octyl ammonium bromide toluene mixed solution to obtain a zinc fluoride ligand modified perovskite quantum dot stock solution; and adding ethyl acetate into the zinc fluoride ligand modified perovskite quantum dot stock solution, and carrying out centrifugal drying to obtain the perovskite quantum dot fluorescent powder. The zinc fluoride inorganic ligand is introduced in the synthesis process and can be more tightly combined with the surface of the perovskite quantum dot, surface defects are effectively passivated, the stability of the quantum dot is remarkably enhanced, and meanwhile the optical performance of the quantum dot is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of quantum dot display luminescence, and specifically relates to a preparation method and application of perovskite quantum dots based on zinc fluoride double shell engineering passivation. Background Art

[0002] Inorganic perovskite (CsPbX 3 ;X = Cl, Br, I) quantum dots (PeQDs) materials have attracted wide attention for their excellent performance in optoelectronic applications. Thanks to their high photoluminescence quantum yield (PLQY), high carrier mobility and tunable emission wavelength, they have shown great potential in optoelectronic devices such as solar cells, high-performance luminescent LEDs and lasers. This potential, especially in the field of luminescence, has rapidly made it a research hotspot.

[0003] At present, the research on perovskite quantum dots mainly focuses on optimizing their optical properties and improving their stability. However, due to the ionic nature of perovskite quantum dots, their inherent thermal instability leads to thermal degradation, which severely limits their practical application in high-temperature environments or high-power devices. Therefore, improving the thermal stability of perovskite quantum dots without sacrificing their optoelectronic properties has become a key challenge that needs to be urgently addressed in this field. To this end, researchers have proposed a variety of strategies to improve the thermal stability of quantum dots. For example, in recent years, a variety of functionalized ligands have been developed, such as oleylamine and oleic acid, octylamine, didodecyldimethylammonium fluoride, etc. These ligands can improve the stability and optical properties of quantum dots to a certain extent, but they are not conducive to the transport of charge carriers. More importantly, these organic ligands may be stripped at high temperatures (>100°C), resulting in poor stability of quantum dots and subsequent LED devices. Therefore, finding a new type of ligand passivation to develop efficient perovskite quantum dots to inhibit thermal degradation at high temperatures remains a rather challenging task.

[0004] Literature shows that core-shell coatings have been widely studied because they are very effective in reducing surface defects, enhancing carrier recombination, and improving thermal stability, such as silicon dioxide, zinc sulfide, cadmium sulfide, etc. However, there are still many problems that cannot be ignored in the practical application of this technology. Due to the strict conditions for shell formation, lattice compatibility, and strict requirements for energy alignment, related research is still relatively small; in addition, the contribution of a single shell structure to optical emission is usually limited.

[0005] In summary, on the basis of achieving efficient luminescence, how to improve the stability of perovskite quantum dots, inhibit thermal degradation, and ensure the maintenance of their excellent performance in different actual application scenarios remains the core issue that needs to be urgently solved in current research. With the continuous deepening of scientific research, the application prospects of perovskite quantum dots in the optoelectronic field, especially in technologies such as high-efficiency white LEDs, are becoming increasingly broad. However, due to the characteristics of perovskite quantum dots themselves, they are extremely vulnerable to the external environment, especially the thermal environment, resulting in serious damage to their luminescence performance and stability, which hinders the further development of this material in practical applications. Summary of the Invention

[0006] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the specification of this application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0007] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method for perovskite quantum dots based on zinc fluoride double-shell engineering passivation.

[0009] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method for perovskite quantum dots based on zinc fluoride double-shell engineering passivation, comprising: Mix cesium carbonate and n-octanoic acid, and wait until the solution is completely transparent to obtain a cesium carbonate-n-octanoic acid mixed solution; Mix lead bromide and tetraoctylammonium bromide with the solvent toluene, stir at room temperature, and wait until the solution is completely transparent to obtain a lead bromide-tetraoctylammonium bromide toluene mixed solution; Mix didodecyldimethylammonium bromide with the solvent toluene, stir at room temperature, and wait until the solution is completely transparent to obtain a didodecyldimethylammonium bromide toluene solution; Mix zinc fluoride, tetraoctylammonium bromide with the solvent toluene, stir at room temperature, and wait until the solution is completely transparent to obtain a zinc fluoride-tetraoctylammonium bromide toluene mixed solution; Mix the cesium carbonate-n-octanoic acid mixed solution and n-octanoic acid solution to obtain a cesium carbonate mixed solution; Add the cesium carbonate mixed solution to the lead bromide-tetraoctylammonium bromide toluene mixed solution, and stir at room temperature to obtain a precursor; Inject the didodecyldimethylammonium bromide toluene solution into the precursor for reaction, and then inject the zinc fluoride-tetraoctylammonium bromide toluene mixed solution, and react for 5 minutes to obtain a zinc fluoride ligand-modified perovskite quantum dot stock solution; Ethyl acetate was added to the perovskite quantum dot stock solution modified with zinc fluoride ligand, and the precipitate was obtained by centrifugation. Subsequently, the precipitate was dissolved and dried in a vacuum drying oven to obtain pure perovskite quantum dot phosphor.

[0010] As a preferred embodiment of the preparation method of the present invention, wherein: the molar ratio of cesium carbonate to n-octanoic acid in the cesium carbonate - n-octanoic acid mixed solution is 1:63.

[0011] As a preferred embodiment of the preparation method of the present invention, wherein: the molar ratio of lead bromide, tetraoctylammonium bromide to toluene in the lead bromide - tetraoctylammonium bromide - toluene mixed solution is 1:2:525.

[0012] As a preferred embodiment of the preparation method of the present invention, wherein: in the didodecyldimethylammonium bromide - toluene solution, the molar ratio of didodecyldimethylammonium bromide to toluene is 1:315.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: in the zinc fluoride - tetraoctylammonium bromide - toluene mixed solution, the molar ratio of zinc fluoride, tetraoctylammonium bromide to toluene is 1:2:525.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: in the cesium carbonate mixed solution, the volume ratio of the cesium carbonate - n-octanoic acid mixed solution to n-octanoic acid is 300:355.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the volume ratio of the lead bromide - tetraoctylammonium bromide - toluene mixed solution, the cesium carbonate mixed solution, the didodecyldimethylammonium bromide - toluene solution, and the zinc fluoride - tetraoctylammonium bromide - toluene mixed solution is 5:0.655:1.66:5.

[0016] 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 9 - 11 nm, and the fluorescence emission peak of the perovskite quantum dot is 515 - 520 nm.

[0017] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of a perovskite quantum dot in the preparation of a white light LED device, including, After drying the perovskite quantum dot into a powder form, yellow phosphor and red phosphor were added and mixed well, and then incorporated into an organic encapsulating silica gel to obtain a mixture; wherein, the volume ratio of organic encapsulating silica gels A and B is 1:4, and the mass ratio of the perovskite quantum dot, yellow phosphor and red phosphor is 7:2:1; Using a 450 nm blue LED chip as the excitation light source, the above mixture was drop-coated on it to obtain a white LED device based on zinc fluoride ligand-passivated perovskite quantum dots.

[0018] Advantages of the present invention: By introducing zinc fluoride inorganic ligands in the synthesis, the present invention optimizes the synthesis method and simply and conveniently prepares highly efficient and stable perovskite quantum at room temperature; the zinc fluoride inorganic ligand can bind more tightly to the surface of the perovskite quantum dots, effectively passivating surface defects, significantly enhancing the stability of the quantum dots, effectively inhibiting the thermal degradation of the perovskite quantum dots, and at the same time improving their optical properties, thus achieving highly efficient and stable light emission; 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

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description 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 zinc fluoride-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 2 Ultraviolet absorption spectrum of zinc fluoride-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 3 X-ray diffraction pattern of zinc fluoride-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 4 Transmission electron microscope image of zinc fluoride-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 5 Thermal stability diagram of zinc fluoride-modified CsPbBr 3 perovskite quantum dots prepared in Example 1 of the present invention; Figure 6 Thermogravimetric analysis diagram of zinc fluoride-modified CsPbBr 3 perovskite quantum dot phosphor prepared in Example 2 of the present invention; Figure 7 Device structure diagram of the white light-emitting LED chip prepared in Example 2 of the present invention; Figure 8 Spectral diagram of the white light LED prepared in Example 2 of the present invention; Figure 9 Chromaticity coordinate diagram of the white light LED prepared in Example 2 of the present invention.

[0020] Figure 10 Photoluminescence efficiency diagram of perovskite quantum dots modified with different molar amounts of zinc fluoride in Comparative Example 1 of the present invention.

[0021] Figure 11 Thermal stability diagram of the sample prepared in Comparative Example 2 of the present invention.

[0022] Figure 12 Spectral diagram of the white light LED prepared in Comparative Example 3 of the present invention. Detailed implementation manners

[0023] To make the above objects, features and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0024] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0025] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.

[0026] Cesium carbonate, lead bromide, tetraoctylammonium bromide and zinc fluoride in the embodiments of the present invention are all purchased from Shanghai Macklin Biochemical Co., Ltd.; n-octanoic acid, didodecyldimethylammonium bromide, and ethyl acetate are all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; toluene is purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.; silicone rubber A and silicone rubber B, Y 3 Al 5 O 12 :Ce yellow phosphor and CaAlSiN 3 :Eu red phosphor are all from Shenzhen Zhanwanglong Technology Co., Ltd.

[0027] Example 1 (1) Mix 0.1 mmol of cesium carbonate and 1 mL of n-octanoic acid, and stir at room temperature for 30 min. When the solution becomes completely transparent, a cesium carbonate-n-octanoic acid mixed solution is obtained.

[0028] (2) Mix 0.09 mmol of lead bromide, 0.18 mmol of tetraoctylammonium bromide and 5 mL of toluene, and stir for 1 h at room temperature. When the solution becomes completely transparent, a mixed solution of lead bromide, tetraoctylammonium bromide and toluene is obtained.

[0029] (3) Mix 0.06 mmol of didodecyldimethylammonium bromide and 2 mL of toluene as the solvent, and stir for 30 min at room temperature. When the solution becomes completely transparent, a didodecyldimethylammonium bromide toluene solution is obtained.

[0030] (4) Mix 0.09 mmol of zinc fluoride, 0.18 mmol of tetraoctylammonium bromide and 5 ml of toluene, and stir for 1 h at room temperature. When the solution becomes completely transparent, a mixed solution of zinc fluoride, tetraoctylammonium bromide and toluene is obtained.

[0031] (5) Mix 0.3 ml of cesium carbonate n - octanoic acid mixed solution and 0.355 ml of n - octanoic acid solution to obtain a cesium carbonate mixed solution.

[0032] (6) Add 0.655 ml of the cesium carbonate mixed solution to the mixed solution of lead bromide, tetraoctylammonium bromide and toluene, and stir for 30 s at room temperature to obtain the final precursor; Inject 1.66 ml of the didodecyldimethylammonium bromide toluene solution into the above - mentioned precursor, react for 2 min, and then inject 5 ml of the mixed solution of zinc fluoride, tetraoctylammonium bromide and toluene, and react for 5 min to obtain a stock solution of perovskite quantum dots modified with zinc fluoride ligands.

[0033] (7) Add the obtained stock solution of quantum dots into a centrifuge tube, and at the same time add ethyl acetate with a volume twice that of the stock solution, and centrifuge at a speed of 10000 r / min for 5 min; After centrifugation, pour off the supernatant, and add 2 ml of toluene in total to the precipitate. Shake the centrifuge tube until the precipitate is completely dissolved, and then centrifuge at a speed of 8000 r / min for 5 min. The obtained supernatant is the pure green - emitting CsPbBr 3 perovskite quantum dot product.

[0034] As Figure 1 shown is the fluorescence emission spectrum of perovskite quantum dots modified with zinc fluoride, and its emission wavelength is at 517 nm.

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

[0036] As Figure 3Shown is the X-ray diffraction pattern of zinc fluoride-modified perovskite quantum dots, which demonstrates the high crystallinity of the sample and indicates that the sample is a standard cubic-phase perovskite crystal.

[0037] As Figure 4 Shown is the transmission electron microscope image of zinc fluoride-modified perovskite quantum dots, with an average size of about 10.22 nm and relatively uniform size.

[0038] To test the thermal stability of the product, the product was heated to 120 °C and the change in luminescence intensity was measured. As Figure 5 shown, after heating for 1 h, the luminescence intensity can still be maintained at about 83% of the initial intensity.

[0039] Example 2 (1) 0.1 mmol of cesium carbonate was mixed with 1 mL of n-octanoic acid and stirred at room temperature for 30 min. When the solution became completely transparent, a cesium carbonate-n-octanoic acid mixed solution was obtained.

[0040] (2) 0.09 mmol of lead bromide, 0.18 mmol of tetraoctylammonium bromide, and 5 mL of toluene were mixed and stirred at room temperature for 1 h. When the solution became completely transparent, a lead bromide-tetraoctylammonium bromide-toluene mixed solution was obtained.

[0041] (3) 0.06 mmol of didodecyldimethylammonium bromide was mixed with 2 mL of the solvent toluene and stirred at room temperature for 30 min. When the solution became completely transparent, a didodecyldimethylammonium bromide-toluene solution was obtained.

[0042] (4) 0.09 mmol of zinc fluoride, 0.18 mmol of tetraoctylammonium bromide, and 5 ml of toluene were mixed and stirred at room temperature for 1 h. When the solution became completely transparent, a zinc fluoride-tetraoctylammonium bromide-toluene mixed solution was obtained.

[0043] (5) 0.3 ml of the cesium carbonate-n-octanoic acid mixed solution was mixed with 0.355 ml of the n-octanoic acid solution to obtain a cesium carbonate mixed solution.

[0044] (6) 0.655 ml of the cesium carbonate mixed solution was added to the lead bromide-tetraoctylammonium bromide-toluene mixed solution and stirred at room temperature for 30 s to obtain the final precursor.

[0045] 1.66 ml of the didodecyldimethylammonium bromide-toluene solution was injected into the above precursor, reacted for 2 min, and then 5 ml of the zinc fluoride-tetraoctylammonium bromide-toluene mixed solution was injected and reacted for 5 min to obtain a zinc fluoride ligand-modified perovskite quantum dot stock solution.

[0046] (7) Add the obtained quantum dot stock solution into a centrifuge tube, and simultaneously add ethyl acetate with a volume twice that of the stock solution. Centrifuge at a speed of 10,000 r / min for 5 min. After centrifugation, pour off the supernatant, and place the precipitate in a vacuum drying oven to dry at 40 °C for 24 h to obtain pure green-emitting CsPbBr 3 perovskite quantum dot phosphor. As Figure 6 shown is the thermogravimetric analysis diagram of the ZnF-modified CsPbBr 3 perovskite quantum dot phosphor, and its yield is calculated to be 82%.

[0047] (8) Thoroughly stir 50 mg of organosilica A and 200 mg of organosilica B, and then add 7 mg of green perovskite quantum dot phosphor, 2 mg of Y 3 Al 5 O 12 :Ce yellow phosphor and 1 mg of CaAlSiN 3 :Eu red phosphor into the mixed AB glue and stir well; Apply the mixed phosphor-containing organosilica AB glue onto a 450 nm blue LED chip, and anneal at 100 °C for 1 hour to solidify the organic encapsulation silica gel to obtain a high-performance white-light-emitting LED chip; The device structure of the chip is as Figure 7 shown, where the blue LED serves as an excitation light source to excite the phosphor mixed coating to emit light and combines to emit white light.

[0048] To test the stability of this product, the change in luminous intensity of the prepared white LED after working for 2 h was tested. As Figure 8 shown, after working for 2 h, the luminous intensity can still be maintained at about 82% of the initial intensity.

[0049] As Figure 9 shown is the chromaticity coordinate diagram of the prepared white LED, and its chromaticity coordinate values are (0.35, 0.32).

[0050] Comparative Example 1 (1) Mix 0.1 mmol of cesium carbonate and 1 mL of n-octanoic acid, and stir at room temperature for 30 min until the solution becomes completely transparent to obtain a cesium carbonate n-octanoic acid mixed solution.

[0051] (2) Mix 0.09 mmol of lead bromide, 0.18 mmol of tetra-n-octylammonium bromide and 5 mL of toluene, and stir at room temperature for 1 h until the solution becomes completely transparent to obtain a lead bromide, tetra-n-octylammonium bromide toluene mixed solution.

[0052] (3) Mix 0.06 mmol of didodecyldimethylammonium bromide with 2 mL of the solvent toluene and stir for 30 min at room temperature. When the solution becomes completely transparent, a didodecyldimethylammonium bromide toluene solution is obtained.

[0053] (4) Mix 0.06, 0.075, 0.09, 0.105, and 0.12 mmol of zinc fluoride with 0.18 mmol of tetraoctylammonium bromide and 5 ml of toluene respectively, and stir for 1 h at room temperature. When the solution becomes completely transparent, toluene mixed solutions of zinc fluoride and tetraoctylammonium bromide with different molar amounts are obtained.

[0054] (5) Mix 0.3 ml of a cesium carbonate n - octanoic acid mixed solution with 0.355 ml of an n - octanoic acid solution to obtain a cesium carbonate mixed solution.

[0055] (6) Add 0.655 ml of the cesium carbonate mixed solution to the lead bromide - tetraoctylammonium bromide toluene mixed solution and stir for 30 s at room temperature to obtain the final precursor; Inject 1.66 ml of the didodecyldimethylammonium bromide toluene solution into the above - mentioned precursor, react for 2 min, and then inject 5 ml of toluene mixed solutions of zinc fluoride and tetraoctylammonium bromide with different molar amounts respectively, and react for 5 min to obtain five kinds of perovskite quantum dot stock solutions modified with zinc fluoride ligands with different molar amounts.

[0056] (7) Add the obtained quantum dot stock solutions to centrifuge tubes respectively, and at the same time add ethyl acetate with twice the volume of the stock solution, and centrifuge at a speed of 10000 r / min for 5 min; After centrifugation, pour off the supernatant, and add 2 ml of toluene in total to the precipitate. Shake the centrifuge tube until the precipitate is completely dissolved, and then centrifuge at a speed of 8000 r / min for 5 min. The obtained supernatant is the pure green - emitting CsPbBr 3 perovskite quantum dot product.

[0057] As Figure 10 shown are the photoluminescence efficiencies of perovskite quantum dots modified with five different molar amounts of zinc fluoride. It can be seen that the effect is the best when the amount of zinc fluoride is 0.09 mmol.

[0058] Comparative Example 2 (1) Mix 0.1 mmol of cesium carbonate with 1 mL of n - octanoic acid and stir for 30 min at room temperature. When the solution becomes completely transparent, a cesium carbonate n - octanoic acid mixed solution is obtained.

[0059] (2) Mix 0.09 mmol of lead bromide, 0.18 mmol of tetraoctylammonium bromide and 5 mL of toluene, and stir for 1 h at room temperature. When the solution becomes completely transparent, a mixed solution of lead bromide, tetraoctylammonium bromide and toluene is obtained.

[0060] (3) Mix 0.06 mmol of didodecyldimethylammonium bromide and 2 mL of toluene as the solvent, and stir for 30 min at room temperature. When the solution becomes completely transparent, a didodecyldimethylammonium bromide toluene solution is obtained.

[0061] (4) Mix 0.09 mmol of zinc bromide, 0.18 mmol of tetraoctylammonium bromide and 5 ml of toluene, and stir for 1 h at room temperature. When the solution becomes completely transparent, a mixed solution of zinc bromide, tetraoctylammonium bromide and toluene is obtained.

[0062] (5) Mix 0.3 ml of a cesium carbonate and n-octanoic acid mixed solution and 0.355 ml of an n-octanoic acid solution to obtain a cesium carbonate mixed solution.

[0063] (6) Add 0.655 ml of the cesium carbonate mixed solution to the mixed solution of lead bromide, tetraoctylammonium bromide and toluene, and stir for 30 s at room temperature to obtain the final precursor; Inject 1.66 ml of the didodecyldimethylammonium bromide toluene solution into the above precursor, react for 2 min, and then inject 5 ml of the mixed solution of zinc bromide, tetraoctylammonium bromide and toluene, and react for 5 min to obtain a stock solution of perovskite quantum dots modified with zinc bromide ligands.

[0064] (7) Add the obtained stock solution of quantum dots to a centrifuge tube and simultaneously add ethyl acetate with a volume twice that of the stock solution, and centrifuge at a speed of 10000 r / min for 5 min; After centrifugation, pour off the supernatant and add 2 ml of toluene in total to the precipitate. Shake the centrifuge tube until the precipitate is completely dissolved, and then centrifuge at a speed of 8000 r / min for 5 min. The obtained supernatant is the pure luminescent CsPbBr 3 perovskite quantum dot product.

[0065] As Figure 11 shown, after the sample was heated for 1 h, the luminescence intensity only remained at about 68% of the initial intensity.

[0066] Comparative Example 3 (1) Mix 0.1 mmol of cesium carbonate and 1 mL of n-octanoic acid, and stir for 30 min at room temperature. When the solution becomes completely transparent, a cesium carbonate and n-octanoic acid mixed solution is obtained.

[0067] (2) Mix 0.09 mmol of lead bromide, 0.18 mmol of tetraoctylammonium bromide and 5 mL of toluene, and stir for 1 h at room temperature. When the solution becomes completely transparent, a mixed solution of lead bromide, tetraoctylammonium bromide and toluene is obtained.

[0068] (3) Mix 0.06 mmol of didodecyldimethylammonium bromide and 2 mL of toluene as the solvent, and stir for 30 min at room temperature. When the solution becomes completely transparent, a didodecyldimethylammonium bromide toluene solution is obtained.

[0069] (4) Mix 0.3 ml of cesium carbonate and n - octanoic acid mixture with 0.355 ml of n - octanoic acid solution to obtain a cesium carbonate mixture.

[0070] (5) Add 0.655 ml of the cesium carbonate mixture to the mixed solution of lead bromide, tetraoctylammonium bromide and toluene, and stir for 30 s at room temperature to obtain the final precursor.

[0071] Inject 1.66 ml of the didodecyldimethylammonium bromide toluene solution into the above - mentioned precursor and react for 2 min to obtain the original perovskite quantum dot stock solution.

[0072] (6) Add the obtained quantum dot stock solution to a centrifuge tube, and at the same time add ethyl acetate with twice the volume of the stock solution, and centrifuge at a speed of 10000 r / min for 5 min; After centrifugation, pour off the supernatant, and place the precipitate in a vacuum drying oven to dry at 40 °C for 24 h to obtain pure green - emitting CsPbBr 3 perovskite quantum dot phosphor.

[0073] (8) Thoroughly stir 50 mg of silicone A and 200 mg of silicone B, and then add 7 mg of green perovskite quantum dot phosphor, 2 mg of Y 3 Al 5 O 12 :Ce yellow phosphor and 1 mg of CaAlSiN 3 :Eu red phosphor into the mixed AB glue and stir well; Apply the mixed phosphor - containing organic AB glue onto a 450 nm blue - light LED chip, and anneal at 100 °C for 1 hour to solidify the organic encapsulating silicone to obtain a high - performance white - light - emitting LED chip; As Figure 12 shown, after the white - light LED prepared from the sample has worked for 2 h, the luminous intensity remains at about 42% of the initial intensity.

[0074] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than 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 zinc fluoride double shell engineering passivation, characterized in that: include, Mixing cesium carbonate and n-octanoic acid until the solution is completely transparent to obtain a cesium carbonate n-octanoic acid mixed solution; Lead bromide and tetra-n-octylammonium bromide are mixed with toluene as a solvent, and stirred at room temperature until the solution becomes completely transparent to obtain a lead bromide-tetra-n-octylammonium bromide toluene mixed solution; Mixing didodecyl dimethyl ammonium bromide and solvent toluene, stirring at room temperature until the solution is completely transparent, to obtain didodecyl dimethyl ammonium bromide toluene solution; Mix zinc fluoride, tetra-n-octylammonium bromide and solvent toluene, and stir at room temperature until the solution becomes completely transparent to obtain a zinc fluoride-tetra-n-octylammonium bromide toluene mixed solution; Mixing the cesium carbonate n-octanoic acid mixed solution with the n-octanoic acid solution to obtain a cesium carbonate mixed solution; The cesium carbonate mixed solution is added into the lead bromide-tetra-n-octylammonium bromide toluene mixed solution, and stirred at room temperature to obtain a precursor; After the didodecyl dimethyl ammonium bromide toluene solution was injected into the precursor for reaction, the zinc fluoride-tetra-n-octylammonium bromide toluene mixed solution was injected and reacted for 5 minutes to obtain the zinc fluoride ligand-modified perovskite quantum dot stock solution; Ethyl acetate is added to the zinc fluoride ligand-modified perovskite quantum dot stock solution, and the precipitate is obtained by centrifugation. The precipitate is then placed in a vacuum drying oven for drying to obtain a pure perovskite quantum dot phosphor.

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

63.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of lead bromide, tetra-n-octylammonium bromide and toluene in the lead bromide, tetra-n-octylammonium bromide and toluene mixed solution is 1:2:

525.

4. The preparation method according to claim 3, characterized in that: The didodecyl dimethyl ammonium bromide toluene solution, wherein the molar ratio of didodecyl dimethyl ammonium bromide to toluene is 1:

315.

5. The preparation method according to claim 1 or 4, characterized in that: The zinc fluoride, tetra-n-octylammonium bromide and toluene mixed solution has a molar ratio of zinc fluoride, tetra-n-octylammonium bromide and toluene of 1:2:

525.

6. The preparation method according to claim 5, characterized in that: The cesium carbonate mixed solution, wherein The volume ratio of the cesium carbonate-octanoic acid mixed solution to octanoic acid is 300:

355.

7. The preparation method according to claim 1 or 6, characterized in that: The volume ratio of the lead bromide-tetra-n-octylammonium bromide toluene mixed solution, the cesium carbonate mixed solution, the didodecyldimethylammonium bromide toluene solution, and the zinc fluoride-tetra-n-octylammonium bromide toluene mixed solution is 5:0.655:1.66:

5.

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 9-11 nm, and the fluorescence emission peak of the perovskite quantum dots is 515-520 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, yellow phosphor and red phosphor are added and mixed thoroughly, and then added into organic encapsulating silica gel to prepare a mixture; wherein the volume ratio of organic encapsulating silica gel A and B is 1:4, and the mass ratio of perovskite quantum dots, yellow phosphor and red phosphor is 7:2:1; A 450 nm blue LED chip was used as the excitation light source, and the above mixture was dripped on it to obtain a white light LED device based on zinc fluoride ligand passivated perovskite quantum dots.

Images