Water-soluble blue light perovskite nanocrystals and methods of making the same

Abstract

The application discloses a water-soluble blue light perovskite nanocrystal material and a preparation method thereof. The material comprises perovskite quantum dots shown in formula (1) and polylactic acid-glycolic acid copolymer (PLGA) coated on the surface of the quantum dots. The water-soluble blue light perovskite nanocrystal material prepared by the application can be used to prepare perovskite nanocrystals with a full blue light emission wavelength range by adjusting the element composition (for example, the proportion of Br and Cl) in the perovskite quantum dots. x Cl 3‑x In formula (1), x is 0-2.8.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of materials science, and relates to a water-soluble blue light perovskite nanocrystal and a preparation method thereof, in particular to a blue light perovskite nanocrystal that can be uniformly dispersed in a water system and a preparation method thereof. BACKGROUND

[0002] All-inorganic cesium lead halide (CsPbX3, X=Cl, Br, I) perovskite nanocrystals (PNCs) have excellent physical and optical properties such as high photoluminescence quantum yield (PLQY), precisely tunable band gap, narrow emission wavelength, high dielectric constant, and large absorption coefficient, making them the candidate materials for the next generation of light-emitting materials. Since the pioneering contribution of Kovalenko and his colleagues in 2015, a large number of PNCs preparation techniques such as hot injection method, solvothermal method, and ligand-assisted deposition method have emerged, and their applications in solar cells, lasers, light-emitting diodes, photodetectors, and biological imaging have been widely explored. Although PNCs have superior performance in various aspects, their further development towards practical applications is severely hindered due to their poor structural stability to external environment.

[0003] Perovskite is very difficult to stably disperse in a water environment because halide anions are sensitive to water and oxygen and can easily react with them. Currently, green-emitting CsPbBr3 PNCs that can stably exist in water have been achieved, but the water stability of blue light perovskite is still very poor, and water-soluble blue light perovskite is rarely reported. Generally, pure blue light perovskite can be prepared by component engineering and quantum confinement methods. Single halide (Br) perovskite can utilize quantum confinement effect to blue-shift to pure blue light by reducing its size. However, for small-sized quantum dots (QDs), their huge surface-to-volume ratio still promotes the generation of a large number of surface defects, resulting in low QDs fluorescence yield and poor stability, and very short lifetime. In terms of component engineering, mixed halide (Br and Cl) perovskite can fully perform band gap tailoring, covering the entire blue spectrum range. On this basis, methods such as adding ligands for surface passivation or using hydrophobic materials for barrier encapsulation can be used to further improve the water resistance of perovskite nanocrystals (PNCs), but the mixture produced by encapsulating PNCs into these polymer matrices cannot be uniformly dispersed in water, and the large particle size is prone to aggregation and sedimentation. Therefore, it is necessary to develop a feasible strategy for a perovskite nanocrystal that can be stably dispersed in water. SUMMARY

[0004] In order to improve the above technical problems, the present application provides a water-soluble blue light perovskite nanocrystal material with high quantum yield and a preparation method thereof. The present application coats perovskite quantum dots by adding amphiphilic polylactic acid-glycolic acid copolymer (PLGA), so that the prepared water-soluble blue light perovskite nanocrystal material can be stably dispersed in water and maintain stable high quantum yield.

[0005] The technical scheme of the present application is as follows:

[0006] A water-soluble blue light perovskite nanocrystal material, the material comprising perovskite quantum dots represented by formula (1) and polylactic acid-glycolic acid copolymer (PLGA) coated on the surface of the quantum dots;

[0007] CsPbBr x Cl 3-x Formula (1)

[0008] wherein x is 0-2.8; preferably 1.5.

[0009] Illustratively, x is 0, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.4, 2.5, 2.8.

[0010] According to an embodiment of the present application, the particle size of the water-soluble blue light perovskite nanocrystal material is 40-100 nm, preferably 40-80 nm, illustratively 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm.

[0011] According to an embodiment of the present application, the raw materials of the perovskite quantum dots are selected from at least two of CsBr, CsCl, PbBr2, PbCl2, preferably CsBr, PbBr2 and PbCl2.

[0012] According to an embodiment of the present application, in the polylactic acid-glycolic acid copolymer (PLGA), the molar ratio of lactic acid to glycolic acid can be (50-90):(10-50), illustratively 90:10, 85:15, 80:20, 75:25, 60:40, 50:50, preferably 75:25, illustratively the polymer is composed of 75% (mol) lactic acid and 25% (mol) glycolic acid.

[0013] According to an embodiment of the present application, the number average molecular weight of the PLGA is 3000-110000, preferably 50000-110000, illustratively 3000, 30000, 43000, 50000, 80000, 110000.

[0014] According to an embodiment of the present application, the mass ratio of the polylactic-co-glycolic acid (PLGA) and the perovskite quantum dots is (300-50):(80-120), preferably (100-150):(100-120), and exemplarily 250:100, 200:100, 150:100, 100:100, 50:100.

[0015] According to an embodiment of the present application, the water-soluble blue light perovskite nanocrystal material is a light yellow uniform solution under sunlight and is blue under ultraviolet lamp (e.g. 365 nm) irradiation.

[0016] According to an embodiment of the present application, the coating can be complete coating or partial coating. For example, when the mass ratio of the perovskite quantum dots represented by formula (1) and the polylactic-co-glycolic acid is at least 100:150, complete coating can be achieved.

[0017] The present application also provides a preparation method of the water-soluble blue light perovskite nanocrystal material, which comprises the following steps:

[0018] (S1) mixing a Cs source, a Pb source and polylactic-co-glycolic acid (PLGA) with a first solvent to prepare a mixed solution;

[0019] (S2) mixing the mixed solution in step (S1) with a second solvent to react, thereby obtaining the water-soluble blue light perovskite nanocrystal material.

[0020] According to an embodiment of the present application, a stabilizer can be further added in step (S1).

[0021] Preferably, the stabilizer is selected from oleic acid or octanoic acid, and is further selected from oleylamine or octylamine. More preferably, the stabilizer is selected from oleic acid and oleylamine, and the volume ratio of the oleic acid and the oleylamine is 1:(0.1-1), and exemplarily 1:0.1, 1:0.2, 1:0.4, 1:0.5, 1:0.6, 1:0.8, 1:1, preferably 1:0.5.

[0022] According to an embodiment of the present application, in step (S1), the Cs source is provided by a Cs-containing compound, which can be at least one of Cs-containing bromide, chloride and fluoride, for example, at least one selected from CsBr, CsCl and CsF. Preferably, the Cs-containing compound is Cs-containing bromide, and exemplarily CsBr.

[0023] According to an embodiment of the present application, in step (S1), the Pb source is provided by a Pb-containing compound, which can be at least one of Pb-containing bromide, chloride, fluoride and iodide, for example, at least one selected from PbBr2, PbCl2, PbF2, and PbI2. More preferably, PbBr2and PbCl2. Illustratively, when the Cs source is not a Cs-containing bromide and a Cs-containing chloride, the Pb source is a Pb-containing bromide and a Pb-containing chloride. Alternatively, when the Pb source is not a Pb-containing bromide and a Pb-containing chloride, the Cs source is a Cs-containing bromide and a Cs-containing chloride.

[0024] According to an embodiment of the present application, in step (S1), the use amount ratio of the Cs source, the Pb source and the polylactic acid-glycolic acid copolymer (PLGA) is (0.1-0.5) mmol:(0.1-0.5) mmol:100 mg, preferably (0.15-0.3) mmol:(0.2-0.4) mmol:100 mg.

[0025] Illustratively, the Pb source is a mixture of PbBr2and PbCl2, and the use amount ratio of the Cs source, PbBr2, PbCl2and the polylactic acid-glycolic acid copolymer is (0.1-0.5) mmol:(0.02-0.3) mmol:(0.05-0.18) mmol:100 mg; and illustratively, 0.1 mmol:0.075 mmol:0.025 mmol:100 mg, 0.2 mmol:0.15 mmol:0.05 mmol:100 mg, 0.4 mmol:0.3 mmol:0.1 mmol:100 mg, 0.2 mmol:0.1 mmol:0.1 mmol:100 mg, 0.2 mmol:0.02 mmol:0.18 mmol:100 mg.

[0026] According to an embodiment of the present application, the first solvent is at least one of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), preferably N,N-dimethylformamide (DMF).

[0027] According to an embodiment of the present application, in step (S1), the use amount ratio of the polylactic acid-glycolic acid copolymer (PLGA) and the first solvent is 100 mg:(2-20) mL, preferably 100 mg:(5-15) mL, illustratively 100 mg:2 mL, 100 mg:5 mL, 100 mg:8 mL, 100 mg:10 mL, 100 mg:15 mL, 100 mg:20 mL.

[0028] According to an embodiment of the present application, in step (S1), the ratio of the amount of the polylactic acid-glycolic acid copolymer (PLGA) and the stabilizer is 100 mg:(0.2-1.0) mL, preferably 100 mg:(0.2-0.8) mL, and exemplarily 100 mg:0.2 mL, 100 mg:0.4 mL, 100 mg:0.6 mL, 100 mg:0.8 mL or 100 mg:1 mL.

[0029] According to an embodiment of the present application, in step (S2), the second solvent is selected from at least one of toluene, chlorobenzene, cyclohexane and n-hexane.

[0030] Preferably, in step (S2), the mixed solution is added into the second solvent in a slow dripping manner. Preferably, the volume ratio of the mixed solution to the second solvent is 1:(5-30), and exemplarily 1:5, 1:10, 1:15, 1:20, 1:25 or 1:30. The speed of dripping is not limited, as long as the mixed solution is dispersed in the second solvent.

[0031] According to an embodiment of the present application, in step (S2), the reaction is carried out at room temperature, and exemplarily at 15-35°C.

[0032] Preferably, the reaction is carried out under stirring. For example, the stirring time is no more than 50 h, and preferably 4-48 h, and exemplarily 4 h, 12 h, 16 h, 24 h, 30 h, 36 h, 40 h or 48 h.

[0033] According to an embodiment of the present application, in step (2), after the reaction is completed, the reaction product can be further subjected to solid-liquid separation and / or drying to prepare the water-soluble blue-light perovskite nanocrystal material.

[0034] Exemplarily, the solid-liquid separation can be carried out by means known in the art, such as centrifugation. Preferably, the centrifugation is carried out at a speed of 6000-12000 rpm, such as 7000-10000 rpm, and exemplarily 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm or 12000 rpm. Further, the centrifugation is carried out for a time of 3-10 min, such as 5-8 min, and exemplarily 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0035] Exemplarily, the drying is carried out at a temperature of 60-90°C, and preferably 70-80°C, and exemplarily 60°C, 70°C, 80°C or 90°C. Further, the drying is carried out for a time of 1-12 h, and preferably 1-10 h, and exemplarily 1 h, 4 h, 8 h, 10 h or 12 h.

[0036] According to an embodiment of the present application, the method for preparing the water-soluble blue light perovskite nanocrystal material further comprises: (S3) dispersing the solid water-soluble blue light perovskite nanocrystal material obtained in step (S2) in water to obtain a water-soluble quantum dot nanomaterial dispersion.

[0037] Preferably, in step (S3), the water-soluble quantum dot nanomaterial dispersion is further subjected to ultrasonic treatment. For example, the ultrasonic treatment is performed for 1-10 min, preferably 2-8 min, and more preferably 1 min, 2 min, 5 min, 8 min or 10 min.

[0038] As a preferred embodiment of the present application, the method for preparing the water-soluble blue light perovskite nanocrystal material comprises the following steps:

[0039] (1) dissolving a Cs source, a Pb source and a polylactic acid-glycolic acid copolymer (PLGA) in a first solvent, and then adding a stabilizer to prepare a mixed solution;

[0040] (2) adding the mixed solution prepared in step (1) to a second solvent (such as toluene, chlorobenzene, cyclohexane or n-hexane) to prepare a water-soluble blue light perovskite nanocrystal solution;

[0041] (3) reacting the water-soluble blue light perovskite nanocrystal solution at room temperature until the coating is complete, and then performing solid-liquid separation on the reaction product, drying the solid product to prepare a water-soluble blue light perovskite nanocrystal material;

[0042] (4) dispersing the dried product in step (3) in water to obtain a water-soluble blue light perovskite nanocrystal aqueous dispersion.

[0043] As a preferred embodiment of the present application, the method for preparing the water-soluble blue light perovskite nanocrystal material comprises the following steps:

[0044] (1) dissolving CsBr, PbBr2, PbCl2 and a polylactic acid-glycolic acid copolymer (PLGA) in N,N-dimethylformamide (DMF), and then adding oleic acid and oleylamine to stabilize the solution after complete dissolution;

[0045] (2) under stirring, taking the above solution and adding it dropwise to a toluene solution to obtain a CsPbBr x Cl 3-x -QDs@PLGA quantum dot solution;

[0046] (3) after sealing, stirring at room temperature to complete the coating to obtain a CsPbBr x Cl 3-x -QDs@PLGA perovskite nanocrystal;

[0047] (4) centrifuging and drying the CsPbBr x Cl 3-x -QDs@PLGA perovskite nanocrystal solution to centrifuge and dry;

[0048] (5) dispersing the product prepared in step (4) in water and ultrasonic, to obtain a uniformly dispersed CsPbBr x Cl 3-x -QDs@PLGA perovskite nanocrystal aqueous dispersion.

[0049] The application also provides a water-soluble blue light perovskite nanocrystal material prepared by the above method.

[0050] According to the application, the water-soluble blue light perovskite nanocrystal material is a solid water-soluble blue light perovskite nanocrystal material or a water-soluble blue light perovskite nanocrystal material dispersion. In particular, it is a water-soluble blue light perovskite nanocrystal material aqueous dispersion.

[0051] The application has the following beneficial effects:

[0052] (1) The application first uses amphiphilic polylactic acid-glycolic acid copolymer (PLGA) to coat blue light perovskite quantum dots (exemplarily, such as CsPbBr 1.5 Cl 1.5 perovskite quantum dots), which improves the long-term stability of blue light perovskite nanocrystals in water and almost completely retains the optical properties of perovskite quantum dots.

[0053] (2) The water-soluble blue light perovskite nanocrystal material prepared by the application can be used to prepare perovskite nanocrystals with a full blue light emission wavelength range by adjusting the element composition (such as the ratio of Br and Cl) of perovskite quantum dots.

[0054] (3) The product of the application uses biodegradable polymers (such as polylactic acid polymers) as coating materials, which are green and environmentally friendly, have good biocompatibility, are easy to operate, have low cost, and can be used for mass production of perovskite nanocrystals.

[0055] (4) The perovskite quantum dots of the application can cover the full blue light spectrum range through anion exchange reaction, and the prepared blue light perovskite quantum dots have high yield and adjustable luminescence. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 fluorescence emission spectrum of CsPbBr 1.5 Cl 1.5 -QDs perovskite quantum dots prepared in Example 1.

[0057] Figure 2 CsPbBr1.5 Cl 1.5 Optical photographs of QDs@PLGA perovskite nanocrystals under sunlight (left) and under UV lamp irradiation (right).

[0058] Figure 3 CsPbBr 1.5 Cl 1.5 Transmission electron micrograph of QDs@PLGA perovskite nanocrystals, nanocrystal particle size ~ 80 nm.

[0059] Figure 4 CsPbBr 1.5 Cl 1.5 QDs quantum dots and CsPbBr 1.5 Cl 1.5 Fluorescence emission spectrum of QDs@PLGA perovskite nanocrystals.

[0060] Figure 5 CsPbBr 1.5 Cl 1.5 Fluorescence emission spectrum of QDs@PLGA perovskite nanocrystals dispersed in water for one month. DETAILED DESCRIPTION

[0061] The technical solutions of the present application will be further described in detail below in combination with specific embodiments. It should be understood that the following examples are only illustratively described and explained the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope of the present application.

[0062] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0063] Example 1

[0064] A CsPbBr 1.5 Cl 1.5 The synthesis method of QDs perovskite quantum dots is as follows:

[0065] (1) 0.2 mmol of CsBr, 0.15 mmol of PbCl2 and 0.05 mmol of PbBr2 were dissolved in 5 mL of N, N-dimethylformamide (DMF) solvent, and after heating and stirring at 60°C to completely dissolve, 0.4 mL of oleic acid and 0.2 mL of oleylamine were added to stabilize the solution;

[0066] (2) 0.5 mL of the mixed solution prepared in step (1) was slowly added to 15 mL of vigorously stirred toluene solution at 60°C, to obtain CsPbBr 1.5Cl 1.5 QDs quantum dot solution.

[0067] (3) The prepared CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots were centrifuged at 8000r for 10min, and the supernatant was separated to obtain the purified CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dot solution.

[0068] Figure 1 CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots prepared in Example 1. As can be seen from the figure, the CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots prepared in the present example have a maximum emission peak of 484nm, and the CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots prepared in the present example have a half-peak width of 23nm. This indicates that the CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots have a narrow fluorescence emission half-peak width, and the absorption edge corresponds to the maximum emission peak of 484nm.

[0069] Example 2

[0070] A method for preparing a water-soluble blue light perovskite nanocrystal material, comprising the following steps:

[0071] (1) 0.2mmol of CsBr, 0.15mmol of PbCl2, and 0.05mmol of PbBr2 and 100mg of polylactic acid-glycolic acid copolymer (PLGA) (the number average molecular weight of PLGA is 110000) were dissolved in 5mL of N,N-dimethylformamide (DMF) solvent, and heated and stirred at 60℃ until completely dissolved. Then, 0.4mL of oleic acid and 0.2mL of oleylamine were added to stabilize the solution;

[0072] (2) 0.5mL of the mixed solution prepared in step (1) was slowly added to 15mL of vigorously stirred toluene solution at 60℃, to obtain CsPbBr 1.5 Cl 1.5 QDs@PLGA quantum dot solution;

[0073] (3) Sealed, low-speed stirring at room temperature for 12h to complete the coating, to obtain CsPbBr 1.5 Cl 1.5 QDs@PLGA perovskite nanocrystal mixed solution;

[0074] (4) The CsPbBr2Cl-QDs@PLGA perovskite nanocrystal mixed solution prepared in step (3) is centrifuged at 8000r for 10min, and the obtained precipitate is dried in an oven at 60°C for 1h; 1.5 Cl 1.5 The CsPbBr2Cl-QDs@PLGA perovskite nanocrystal mixed solution prepared in step (3) is centrifuged at 8000r for 10min, and the obtained precipitate is dried in an oven at 60°C for 1h;

[0075] (5) 2-4mL water is added to the dried product of step (4), and ultrasonic treatment is performed for 2min, to obtain a uniformly dispersed CsPbBr2Cl-QDs@PLGA perovskite nanocrystal dispersion. 1.5 Cl 1.5 The CsPbBr2Cl-QDs@PLGA perovskite nanocrystal mixed solution prepared in step (3) is centrifuged at 8000r for 10min, and the obtained precipitate is dried in an oven at 60°C for 1h;

[0076] Example 3

[0077] A method for preparing a water-soluble sky blue light perovskite nanocrystal material, comprising the following steps:

[0078] (1) 0.2mmol CsBr, 0.1mmol PbCl2, 0.1mmol PbBr2 and 100mg of polylactic acid-glycolic acid copolymer (PLGA) (the number average molecular weight of PLGA is 110000) are dissolved in 5mL of N,N-dimethylformamide (DMF) solvent, and after complete dissolution by heating and stirring at 60°C, 0.4mL of oleic acid and 0.2mL of oleylamine are added for stabilizing the solution;

[0079] (2) 0.5mL of the mixed solution prepared in step (1) is slowly added dropwise into 15mL of methylbenzene solution under stirring at 60°C, to obtain a CsPbBr2Cl-QDs@PLGA quantum dot solution;

[0080] (3) Sealing, low-speed stirring at room temperature for 12h to complete the coating, to obtain a CsPbBr2Cl-QDs@PLGA perovskite nanocrystal mixed solution;

[0081] (4) The CsPbBr2Cl-QDs@PLGA perovskite nanocrystal mixed solution prepared in step (3) is centrifuged at 8000r for 10min, and the obtained precipitate is dried in an oven at 60°C for 1h;

[0082] (5) 2-4mL water is added to the dried product of step (4), and ultrasonic treatment is performed for 2min, to obtain a uniformly dispersed CsPbBr2Cl-QDs@PLGA perovskite nanocrystal dispersion.

[0083] The emission peak of the CsPbBr2Cl-QDs@PLGA perovskite nanocrystal dispersion prepared by example 3 is about 490nm, which belongs to the range of sky blue light, and thus it can be seen that with the increase of Br composition, the emission peak of perovskite is red-shifted and deviates from the emission range of pure blue light.

[0084] Example 4

[0085] A method for preparing a water-soluble blue perovskite nanocrystal material, comprising the following steps:

[0086] (1) Dissolve 0.2 mmol of CsBr, 0.18 mmol of PbCl2, and 0.02 mmol of PbBr2 and 100 mg of polylactic acid-glycolic acid copolymer (PLGA) (the number average molecular weight of PLGA is 110000) in 5 mL of N,N-dimethylformamide (DMF) solvent, heat and stir at 60°C until completely dissolved, then add 0.4 mL of oleic acid and 0.2 mL of oleylamine for stabilizing the solution;

[0087] (2) Take 0.5 mL of the mixed solution prepared in step (1) and slowly drop it into 15 mL of methylbenzene solution stirred at 60°C, to obtain CsPbBr 1.2 Cl 1.8 QDs@PLGA quantum dot solution;

[0088] (3) Seal and stir at low speed at room temperature for 12 h to complete the coating, to obtain CsPbBr 1.2 Cl 1.8 QDs@PLGA perovskite nanocrystal mixed solution;

[0089] (4) Centrifuge the CsPbBr 1.2 Cl 1.8 QDs@PLGA perovskite nanocrystal mixed solution prepared in step (3) at 8000 r for 10 min, and dry the obtained precipitate in an oven at 60°C for 1 h;

[0090] (5) Add 2-4 mL of water to the dried product of step (4) and ultrasonic for 2 min, to obtain a uniformly dispersed CsPbBr 1.2 Cl 1.8 QDs@PLGA perovskite nanocrystal dispersion.

[0091] The emission peak of the CsPbBr 1.2 Cl 1.8 QDs@PLGA perovskite nanocrystal dispersion prepared by Example 4 is about 480 nm, which belongs to the blue light range, but the fluorescence intensity is significantly weakened, and the solution is slightly turbid. With the increase of Cl composition, the solubility of Pb source is reduced, so that the fluorescence of the prepared perovskite quantum dots is weakened.

[0092] Example 5

[0093] A method for preparing a water-soluble blue perovskite nanocrystal material, comprising the following steps:

[0094] (1) 0.2 mmol of CsCl and 0.2 mmol of PbCl2 and 100 mg of polylactic acid-glycolic acid copolymer (PLGA) (the number average molecular weight of PLGA is 110000) were dissolved in 5 mL of N, N-dimethylformamide (DMF) solvent, and after complete dissolution by heating and stirring at 60°C, 0.4 mL of oleic acid and 0.2 mL of oleylamine were added for stabilizing the solution;

[0095] (2) 0.5 mL of the mixed solution prepared in step (1) was slowly added dropwise into 15 mL of toluene solution under stirring at 60°C, to obtain a CsPbCl3-QDs@PLGA quantum dot solution;

[0096] (3) The reaction was sealed and stirred at low speed at room temperature for 12 h to complete the coating, to obtain a CsPbCl3-QDs@PLGA@PLGA perovskite nanocrystal mixed solution;

[0097] (4) The CsPbCl3-QDs@PLGA perovskite nanocrystal mixed solution prepared in step (3) was centrifuged at 8000 r for 10 min, and the obtained precipitate was dried in an oven at 60°C for 1 h;

[0098] (5) 2-4 mL of water was added to the dried product of step (4) and ultrasonicated for 2 min, to obtain a uniformly dispersed CsPbCl3-QDs@PLGA perovskite nanocrystal dispersion.

[0099] The CsPbCl3-QDs@PLGA perovskite nanocrystal dispersion prepared by Example 5 was relatively turbid, had very weak fluorescence intensity, and had poor optical performance. The solubility of CsCl in this system was poor, and with the disappearance of Br component, the solubility of Cs source and Pb source was reduced, so that the fluorescence of the prepared perovskite quantum dots was weakened.

[0100] Test Example

[0101] Figure 2 Optical photographs of the CsPbBr 1.5 Cl 1.5 -QDs@PLGA perovskite nanocrystal dispersion prepared in Example 2 under sunlight (left) and under ultraviolet lamp irradiation (right). As can be seen from the figure, the CsPbBr 1.5 Cl 1.5 -QDs@PLGA perovskite nanocrystal prepared in the present embodiment was well dispersed in water, could form a uniform aqueous solution, and still had excellent luminescent performance.

[0102] Figure 3 Optical photographs of the CsPbBr 1.5 Cl 1.5TEM image of QDs@PLGA perovskite nanocrystals. It can be seen from the figure that the CsPbBr 1.5 Cl 1.5 The particle size of QDs@PLGA perovskite nanocrystals is about 80 nm, which is larger than that of the CsPbBr 1.5 Cl 1.5 The particle size of QDs perovskite quantum dots is increased, which indicates that the polylactic acid-glycolic acid copolymer (PLGA) is successfully coated on the CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots.

[0103] Figure 4 The CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots and the CsPbBr 1.5 Cl 1.5 QDs@PLGA perovskite nanocrystals. 1.5 Cl 1.5 The emission peak of QDs@PLGA perovskite nanocrystals is slightly red-shifted, but the fluorescence intensity is basically unchanged, indicating that the perovskite nanocrystals coated with polymers still have excellent luminescent properties.

[0104] Figure 5 The CsPbBr 1.5 Cl 1.5 QDs@PLGA perovskite nanocrystals dispersed in water for one day and one month. It can be seen from the figure that the CsPbBr 1.5 Cl 1.5 QDs@PLGA perovskite nanocrystals dispersed in water for one month, the emission peak basically does not move obviously, and the fluorescence intensity is basically unchanged. It is indicated that the polylactic acid-glycolic acid copolymer (PLGA) is coated on the CsPbBr 1.5 Cl 1.5 QDs perovskite quantum dots, not only realizes the stable existence of perovskite quantum dots in water, but also almost completely retains the optical properties of perovskite quantum dots (has basically no effect on its fluorescence intensity), and the water-soluble CsPbBr 1.5 Cl 1.5 QDs@PLGA perovskite nanocrystals still have a high fluorescence intensity.

[0105] The above has exemplarily described the embodiments of the present application. However, the protection scope of the present application is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A water-soluble blue light perovskite nanocrystal material, characterized in that, The material comprises perovskite quantum dots shown in formula (1) and polylactic acid-glycolic acid copolymer coated on the surface of the quantum dots; CsPbBr x Cl 3-x Formula (1) Wherein, x is 1.2-2; The number average molecular weight of the polylactic acid-glycolic acid copolymer is 50000-110000; In the polylactic acid-glycolic acid copolymer, the molar ratio of lactic acid and glycolic acid is (50-90):(10-50); The mass ratio of the polylactic acid-glycolic acid copolymer and perovskite quantum dots is (300-50):(80-120).

2. The material of claim 1, wherein, The particle size of the water-soluble blue light perovskite nanocrystal material is 40-100 nm.

3. The material of claim 1, wherein, The raw material of the perovskite quantum dots is selected from at least one of CsBr, CsCl, PbBr2 and PbCl2.

4. The material of claim 1, wherein The water-soluble blue light perovskite nanocrystal material is a light yellow uniform solution under sunlight and is blue under ultraviolet lamp irradiation.

5. Process for the production of the material according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: (S1) mixing a Cs source, a Pb source and a polylactic acid-glycolic acid copolymer with a first solvent to prepare a mixed solution; (S2) mixing the mixed solution in step (S1) with a second solvent to react, thereby preparing a water-soluble blue light perovskite nanocrystal material.

6. The method of claim 5, wherein, A stabilizer is further added in step (S1); The stabilizer is selected from oleic acid or octanoic acid, and is further selected from oleylamine or octylamine.

7. The method of claim 6, wherein, The stabilizer is selected from oleic acid and oleylamine, and the volume ratio of oleic acid to oleylamine is 1:(0.1-1).

8. The method of claim 5, wherein, In step (S1), the Cs source is selected from at least one of CsBr and CsCl; The Pb source is selected from at least one of PbBr2 and PbCl2.

9. The method of claim 5, wherein, In step (S1), the amount ratio of the Cs source, the Pb source and the polylactic acid-glycolic acid copolymer is (0.1-0.5) mmol:(0.1-0.5) mmol:100 mg.

10. The method of claim 5, wherein, The first solvent is at least one of N,N-dimethylformamide and dimethyl sulfoxide.

11. The method of claim 5, wherein, In step (S2), the second solvent is selected from at least one of toluene, chlorobenzene, cyclohexane and n-hexane.

12. The method of claim 5, wherein, The method further comprises: (S3) dispersing the water-soluble blue light perovskite nanocrystal material in a solid state obtained in step (S2) in water to obtain a water-soluble quantum dot nanomaterial dispersion.

13. The method of claim 5, wherein, The method specifically comprises the following steps: (1) dissolving a Cs source, a Pb source and a polylactic acid-glycolic acid copolymer in a first solvent, and then adding a stabilizer to prepare a mixed solution; (2) adding the mixed solution prepared in step (1) into a second solvent to prepare a water-soluble blue light perovskite nanocrystal solution; (3) reacting the water-soluble blue light perovskite nanocrystal solution at room temperature to make the coating complete; and performing solid-liquid separation on the reaction product; drying the solid product to prepare a water-soluble blue light perovskite nanocrystal material; (4) dispersing the dried product in step (3) in water to obtain a water-soluble blue light perovskite nanocrystal aqueous dispersion.

14. The water-soluble blue light perovskite nanocrystal material prepared by the method of any one of claims 5-13.

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