Preparation method of fluorinated cross-linked microsphere coated perovskite quantum dot powder

Abstract

The invention discloses a preparation method of fluorinated cross-linked microsphere coated perovskite quantum dot powder, and the preparation method comprises the following steps: (1) taking a monomer A, polyvinylpyrrolidone and a solvent, adding into a reaction container, heating in a nitrogen atmosphere, and adding an initiator; (2) after reacting for a certain time, adding a cross-linking agent, a fluorine-containing monomer, a monomer B and a solvent, continuously reacting, and after the reaction is finished, washing, filtering and drying to obtain fluorinated cross-linked microspheres; the monomer B is the same as the monomer A; and (3) taking the fluorinated cross-linked microspheres, adding the fluorinated cross-linked microspheres into the perovskite quantum dot solution, performing swelling, performing centrifugation after swelling is completed, adding n-hexane into a precipitate obtained by centrifugation for shrinkage, and performing drying in a vacuum drying oven after centrifugation to obtain the fluorinated cross-linked microsphere coated perovskite quantum dot powder. The fluoridized cross-linked microsphere coated perovskite quantum dot powder prepared by the invention can improve the stability of quantum dots in water while retaining the fluorescence property.

Description

Technical Field

[0001] The present invention relates to the field of materials, and particularly to a preparation method of a perovskite quantum dot powder coated with fluorinated crosslinked microspheres. Background Art

[0002] In recent years, perovskite quantum dots (PQDs) have been widely concerned and studied due to their excellent optoelectronic properties. Perovskite quantum dots are a class of fluorescent semiconductor nanocrystal materials with a size range less than 20 nm, which are divided into organic-inorganic hybrid perovskites and all-inorganic perovskite quantum dots. Among them, CsPbX 3 All-inorganic perovskite quantum dots have been widely used in anti-counterfeiting, display fields, LEDs devices, biological fields, and solar cells, etc., due to their excellent optoelectronic properties, such as good biocompatibility, high fluorescence quantum yield, narrow emission peak, emission spectrum covering the entire visible light wavelength, continuously tunable emission wavelength, and quantum confinement effect.

[0003] However, due to the traditional CsPbX 3 Perovskite luminescent materials are susceptible to the influence of oxygen, humidity, temperature, and light, resulting in internal intrinsic phase transitions and decomposition, seriously hindering the application of perovskite quantum dots in various fields. And due to the phenomenon of halogen migration occurring when perovskite quantum dots composed of different halogens are mixed, the application is affected. Researchers have adopted methods such as ligand modification, inorganic coating, and doping at the A-site, B-site, and X-site to improve the stability of quantum dots, but the above methods are relatively complex in process and difficult to promote. The method of encapsulating perovskite quantum dots with polymer microspheres not only improves the stability of perovskite quantum dots, but also has a simple preparation process and easily available raw materials. However, the stability of currently polymer-encapsulated perovskite quantum dots still needs to be further improved.

[0004] Selecting a fluorine-containing polymer to encapsulate perovskite quantum dots not only does not damage the fluorescence effect, but also the fluorine-containing polymer has better hydrophobicity, so it can enhance the stability of quantum dots, with a simple preparation process and easily obtainable raw materials. Based on this, the present invention uses fluorinated crosslinked polymer microspheres to encapsulate perovskite quantum dots to protect the quantum dots from damage by the external environment and have excellent water resistance. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a preparation method of a perovskite quantum dot powder coated with fluorinated crosslinked microspheres. The preparation process of this method is simple, the raw materials are simple, and the prepared composite powder has excellent water resistance.

[0006] The technical solution adopted by the present invention to solve the above technical problems is specifically as follows:

[0007] A preparation method of a perovskite quantum dot powder coated with fluorinated crosslinked microspheres, comprising the following steps:

[0008] (1) Weigh an appropriate amount of monomer A, polyvinylpyrrolidone, and solvent and add them to a reaction vessel. Under a nitrogen atmosphere, raise the temperature to 60 - 80 °C and then add the initiator; monomer A is selected from at least one of methyl methacrylate, styrene, or butyl acrylate; the solvent is a mixed solvent of ethanol and water, where the mass ratio of ethanol to water is 1:1 - 2; the feeding ratio of monomer A, polyvinylpyrrolidone, solvent, and initiator is 4:0.7 - 1:60 - 100:0.04 - 0.06;

[0009] (2) After reacting for 60 - 120 min, add the crosslinking agent, fluorine-containing monomer, monomer B, and solvent, and continue the reaction. After the reaction is completed, wash, filter, and dry to obtain fluorinated crosslinked microspheres; the crosslinking agent is selected from at least one of divinylbenzene, ethylene glycol dimethacrylate, and diisocyanate, the fluorine-containing monomer is selected from at least one of dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, trifluoroethyl acrylate, and hexafluorobutyl acrylate, and monomer B is the same as monomer A; the feeding mass ratio of monomer A, crosslinking agent, fluorine-containing monomer, monomer B, and solvent is 4:0.5 - 1.5:0.5 - 1.5:1 - 3:30 - 50;

[0010] (3) Weigh the fluorinated crosslinked microspheres, add them to a perovskite quantum dot solution with a concentration of 2 - 5 wt%, and perform swelling. After swelling is completed, centrifuge, add n-hexane to the precipitate obtained by centrifugation for shrinking, and dry in a vacuum oven after centrifugation to obtain fluorinated crosslinked microsphere-coated perovskite quantum dot powder; the feeding ratio of the fluorinated crosslinked microspheres to the perovskite quantum dot solution is 1 g:8 - 12 mL.

[0011] Preferably, the initiator is azobisisobutyronitrile, azobisisoheptonitrile, or benzoyl peroxide.

[0012] Preferably, the feeding mass ratio of monomer A, crosslinking agent, fluorine-containing monomer, and monomer B is 4:1:0.8:2.

[0013] Preferably, the solvent of the perovskite quantum dot solution is toluene, p-xylene, or ethyl acetate.

[0014] Preferably, in step (3), the swelling time is 2 - 10 h.

[0015] Preferably, in step (3), the concentration of the perovskite quantum dot solution is 3 - 4 wt%, and the feeding ratio of the fluorinated crosslinked microspheres to the perovskite quantum dot solution is 1 g:10 mL.

[0016] In the preparation method of the fluorinated crosslinked microsphere-coated perovskite quantum dot powder provided by the present invention, after the perovskite quantum dots are encapsulated by the fluorinated crosslinked microspheres, the quantum dots have excellent stability in water and can maintain 70% of the initial fluorescence intensity after being soaked in water for 45 days.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The perovskite quantum dots are encapsulated by fluoropolymer crosslinked microspheres. By utilizing the property that the crosslinked polymer can only be swollen but not dissolved, a good solvent is used to open the chain structure of the polymer, enabling the perovskite fluorescent nanoparticles to enter the interior of the microspheres under the condition of concentration difference, and the external hydrophobicity protects the perovskite quantum dots from being damaged by external water.

[0019] (2) The perovskite quantum dot fluoropolymer crosslinked microspheres prepared by the present invention can improve the stability of perovskite quantum dots in water while retaining the fluorescence performance.

[0020] (3) The perovskite quantum dot fluoropolymer crosslinked microspheres of the present invention have characteristics such as high safety and high waterproofness. Description of the Drawings

[0021] Figure 1 is a comparison diagram of the fluorinated crosslinked microsphere-coated perovskite quantum dots prepared in Example 1 of the present invention under natural light (a) and 365 nm ultraviolet light (b);

[0022] Figure 2 is a scanning electron microscope image of the fluorinated crosslinked microsphere-coated perovskite quantum dots prepared in Example 2 of the present invention;

[0023] Figure 3 is a photograph of the fluorinated crosslinked microsphere-coated perovskite quantum dots prepared in Example 4 of the present invention changing under 365 nm ultraviolet light in water over time.

[0024] Figure 4 is the pure PMMA-coated CsPbBr prepared in Comparative Example 1 3 Quantum dots and a graph showing the change in fluorescence intensity over time of the fluorinated crosslinked microsphere-coated perovskite quantum dots prepared in Example 1 in water.

[0025] Figure 5 is CsPbBr 3 A fluorescence intensity graph of the quantum dot toluene solution and the fluorinated crosslinked microsphere-coated perovskite quantum dots prepared in Example 1. Detailed Embodiments

[0026] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be specifically described below in conjunction with the embodiments and the drawings.

[0027] In the following examples, unless otherwise specified, all are commercially available products.

[0028] The perovskite quantum dots used in the embodiments of the present invention are CsPbBr 3 quantum dots, which are obtained by the thermal injection method. The specific preparation steps are as follows:

[0029] (1) Add 0.407 g of cesium carbonate powder, 1.25 mL of OA, and 20 mL of OED into a 50 mL three-necked flask. Under a nitrogen atmosphere, heat up to 120 °C and continuously stir for 1 h. Then raise the temperature to 150 °C until the solution becomes transparent and clear to prepare the cesium oleate precursor.

[0030] (2) Add 5 mL of OED liquid and 0.069 g of lead bromide powder into a 50 mL three-necked flask. Heat up to 120 °C in a nitrogen atmosphere, then add 0.5 mL each of OA and OAM. After the powder disappears, raise the temperature to 160 °C, add 0.4 mL of preheated cesium oleate. After 5 s, cool in an ice-water bath. The obtained quantum dot solution is centrifuged at 3000 rpm for 5 min at 0 °C to obtain 0.4 g of quantum dot precipitate. The obtained quantum dots are stored in 12.5 g of solvent (the solvent is toluene, p-xylene, or ethyl acetate), where the concentration of CsPbBr 3 quantum dots is 3.1 wt%. The fluorescence intensity of the CsPbBr 3 quantum dot toluene solution with a concentration of 3.1 wt% is shown in Figure 5 .

[0031] Example 1

[0032] This example provides a preparation method of fluorinated crosslinked microsphere-coated perovskite quantum dot powder, including the following steps:

[0033] (1) Weigh 4 g of methyl methacrylate, 0.9 g of polyvinylpyrrolidone, 40 g of water, and 40 g of ethanol and add them into a 250 mL three-necked flask. Under a nitrogen atmosphere, raise the temperature to 70 °C and then add 0.06 g of azobisisobutyronitrile;

[0034] (2) After 1.5 h, add 1 g of ethylene glycol dimethacrylate, 0.8 g of trifluoroethyl methacrylate, 2 g of methyl methacrylate, 20 mL of ethanol, and 20 mL of water, and continuously react for 8 h. After the reaction is completed, wash, filter, and dry the crosslinked microspheres;

[0035] (3) Weigh 1 g of crosslinked microspheres and add 10 mL of CsPbBr 3In a toluene solution of quantum dots, swelling was carried out for 5 h. After the swelling was completed, centrifugation was performed. n-Hexane was added to the precipitate obtained by centrifugation for shrinking, and after centrifugation, it was dried in a vacuum oven to obtain a powder of fluorinated crosslinked microspheres coated with perovskite quantum dots. The photos of the fluorinated crosslinked microspheres coated with perovskite quantum dots prepared in Example 1 under natural light and 365 nm ultraviolet light are shown in Figure 1 , and the fluorescence intensity of the powder of fluorinated crosslinked microspheres coated with perovskite quantum dots is shown in Figure 5 .

[0036] Example 2

[0037] This example provides a method for preparing a powder of fluorinated crosslinked microspheres coated with perovskite quantum dots.

[0038] (1) The experimental apparatus and operations were the same as in Example 1. In step (1), 4.0 g of methyl methacrylate was replaced with 4.0 g of styrene, and 0.06 g of azodiisooctanenitrile was replaced with 0.06 g of azodiisobutyronitrile.

[0039] (2) The experimental apparatus and operations were the same as in Example 1. In step (2), 1 g of EDGMA was replaced with 1 g of divinylbenzene, 0.8 g of trifluoroethyl methacrylate was replaced with 0.8 g of dodecafluoroheptyl methacrylate, and 2 g of methyl methacrylate was replaced with 2 g of styrene.

[0040] (3) The experimental apparatus and operations were the same as in Example 1. In step (3), 10 mL of CsPbBr 3 toluene solution was replaced with 10 mL of CsPbBr 3 p-xylene solution.

[0041] (4) The experimental apparatus and operations were the same as in Example 1. The swelling time in step (3) was changed from 5 h to 8 h.

[0042] The scanning electron microscope image of the fluorinated crosslinked microspheres coated with perovskite quantum dots prepared in Example 2 is shown in Figure 2 .

[0043] Example 3

[0044] This example provides a method for preparing a powder of fluorinated crosslinked microspheres coated with perovskite quantum dots.

[0045] (1) The experimental apparatus and operations were the same as in Example 1. In step (1), 4.0 g of methyl methacrylate was replaced with 4.0 g of butyl acrylate, and 0.06 g of azodiisooctanenitrile was replaced with 0.06 g of dibenzoyl peroxide.

[0046] (2) The experimental apparatus and operations are the same as those in Example 1. Replace 1 g of EDGMA in step (2) with 1 g of diisocyanate, 0.8 g of trifluoroethyl methacrylate with 0.8 g of hexafluorobutyl acrylate, and 2 g of methyl methacrylate with 2 g of butyl acrylate.

[0047] (3) The experimental apparatus and operations are the same as those in Example 1. Replace 10 mL of CsPbBr 3 toluene solution in step (3) with 10 mL of CsPbBr 3 ethyl acetate solution.

[0048] (4) The experimental apparatus and operations are the same as those in Example 1. Replace the swelling time of 5 h in step (3) with 3 h.

[0049] Example 4

[0050] This example provides a method for preparing fluorinated crosslinked microsphere-coated perovskite quantum dot powder.

[0051] (1) The experimental apparatus and operations are the same as those in Example 1. Replace 4.0 g of methyl methacrylate with 4.0 g of styrene and 0.06 g of azodiisooctanenitrile with 0.06 g of dibenzoyl peroxide in step (1).

[0052] (2) The experimental apparatus and operations are the same as those in Example 1. Replace 1 g of EDGMA in step (2) with 1 g of divinylbenzene, 0.8 g of trifluoroethyl methacrylate with 0.8 g of hexafluorobutyl acrylate, and 2 g of methyl methacrylate with 2 g of styrene.

[0053] (3) The experimental apparatus and operations are the same as those in Example 1. Replace 10 mL of CsPbBr 3 toluene solution in step (3) with 10 mL of CsPbBr 3 p-xylene solution.

[0054] (4) The experimental apparatus and operations are the same as those in Example 1. Replace the swelling time of 5 h in step (3) with 10 h. Place the obtained fluorinated crosslinked microsphere-coated perovskite quantum dot powder in water and take pictures under ultraviolet light in a dark environment at regular intervals to obtain Figure 3 .

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing unfluorinated crosslinked microsphere-coated perovskite quantum dot powder, including the following steps:

[0057] (1) Weigh 4 g of methyl methacrylate, 0.9 g of polyvinylpyrrolidone, 40 g of water and 40 g of ethanol and add them to a 250 mL three-necked flask. Under a nitrogen atmosphere, raise the temperature to 70 °C and then add 0.06 g of azobisisobutyronitrile;

[0058] (2) Add 1 g of ethylene glycol dimethacrylate, 2 g of methyl methacrylate, 20 mL of ethanol and 20 mL of water after 1.5 h, and continue the reaction for 8 h. After the reaction is completed, wash the crosslinked microspheres, filter and dry them;

[0059] (3) Weigh 1 g of crosslinked microspheres, add them to 10 mL of a quantum dot toluene solution, and swell for 5 h. After swelling is completed, centrifuge, add n-hexane to the precipitate obtained by centrifugation for shrinking, and dry in a vacuum oven after centrifugation to obtain non-fluorinated crosslinked microsphere-coated perovskite quantum dot powder.

[0060] Put the non-fluorinated crosslinked microsphere-coated perovskite quantum dot powder prepared in Comparative Example 1 and the fluorinated crosslinked microsphere-coated perovskite quantum dot powder prepared in Example 1 into water respectively, and record the fluorescence intensity measured by a fluorescence spectrophotometer at regular intervals to obtain Figure 4 .

Claims

1. A method for preparing fluorinated cross-linked microsphere-coated perovskite quantum dot powder, characterized in that: The preparation method comprises the following steps: (1) Weighing appropriate amounts of monomer A, polyvinyl pyrrolidone, and solvent and adding them into a reaction container, raising the temperature to 60-80° C. under a nitrogen atmosphere, and then adding an initiator; the monomer A is selected from at least one of methyl methacrylate, styrene, or butyl acrylate; the solvent is a mixed solvent of ethanol and water, wherein the mass ratio of ethanol to water is 1:1-2; the feed ratio of the monomer A, polyvinyl pyrrolidone, solvent, and initiator is 4:0.7-1.:60-100:0.04-0.06; (2) After reacting for 60 to 120 minutes, adding a crosslinking agent, a fluorine-containing monomer, a monomer B and a solvent, and continuing the reaction. After the reaction is completed, washing, filtering and drying are performed to obtain fluorinated crosslinked microspheres; the crosslinking agent is selected from at least one of divinylbenzene, ethylene glycol dimethacrylate and diisocyanate; the fluorine-containing monomer is selected from at least one of dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, trifluoroethyl acrylate and hexafluorobutyl acrylate; the monomer B is the same as the monomer A; the mass ratio of the monomer A, the crosslinking agent, the fluorine-containing monomer, the monomer B and the solvent is 4:0.5-1.5:0.5-1.5:1-3:30-50; (3) Weighing fluorinated cross-linked microspheres, adding them to a perovskite quantum dot solution with a concentration of 2-5wt%, swelling them, centrifuging them after swelling is completed, adding n-hexane to the precipitate obtained by centrifugation to shrink it, and drying them in a vacuum oven after centrifugation to obtain fluorinated cross-linked microsphere-coated perovskite quantum dot powder; the feed ratio of the fluorinated cross-linked microspheres to the perovskite quantum dot solution is 1g:8-12mL.

2. The preparation method according to claim 1, characterized in that: The initiator is azobisisobutyronitrile, azobisisoheptanenitrile or dibenzoyl peroxide.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the monomer A, the cross-linking agent, the fluorine-containing monomer and the monomer B is 4:1:0.8:

2.

4. The preparation method according to claim 1, characterized in that: The solvent of the perovskite quantum dot solution is toluene, p-xylene or ethyl acetate.

5. The preparation method according to claim 1, characterized in that: In step (3), the swelling time is 2 to 10 hours.

6. The preparation method according to claim 1, characterized in that: In step (3), the concentration of the perovskite quantum dot solution is 3-4wt%, and the feed ratio of the fluorinated cross-linked microspheres to the perovskite quantum dot solution is 1g:10mL.

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