Preparation method of perovskite quantum dot powder coated by fluorinated crosslinked microspheres

Abstract

The application discloses a preparation method of fluorinated cross-linked microsphere-coated perovskite quantum dot powder, and comprises the following steps: (1) monomer A, polyvinylpyrrolidone and a solvent are taken into a reaction container, an initiator is added after temperature rising under a nitrogen atmosphere; (2) after reaction for a certain time, a cross-linking agent, a fluorine-containing monomer, monomer B and a solvent are added, and the reaction is continuously carried out, and after the reaction is completed, washing, filtering and drying are carried out to obtain fluorinated cross-linked microspheres; the monomer B is the same as the monomer A; (3) fluorinated cross-linked microspheres are taken, perovskite quantum dot solution is added for swelling, centrifugation is carried out after the swelling is completed, n-hexane is added to the obtained precipitate for shrinkage, and the fluorinated cross-linked microsphere-coated perovskite quantum dot powder is obtained after drying in a vacuum oven. The fluorinated cross-linked microsphere-coated perovskite quantum dot powder prepared by the method can retain the fluorescence performance and improve the stability of quantum dots in water.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of materials, in particular to a preparation method of fluorinated cross-linked microspheres coated perovskite quantum dot powder. BACKGROUND

[0002] In recent years, perovskite quantum dots (PQDs) have been widely concerned and studied due to their excellent photoelectric properties. Perovskite quantum dots are a class of fluorescent semiconductor nanocrystalline materials with a size range of less than 20 nm, which are divided into organic-inorganic hybrid perovskite and all-inorganic perovskite quantum dots. Among them, CsPbX3 all-inorganic perovskite quantum dots are widely used in anti-counterfeiting, display field, LEDs device, biological field and solar cell, etc. due to their excellent photoelectric properties, such as good biocompatibility, high fluorescence quantum yield, narrow emission peak, emission spectrum covering the entire visible light wavelength, continuous adjustable emission wavelength, quantum confinement effect, etc.

[0003] However, the traditional CsPbX3 perovskite luminescent material is easily affected by oxygen, humidity, temperature and light, which causes internal intrinsic phase transition and decomposition, seriously hindering the application of perovskite quantum dots in various fields. In addition, the mixing of perovskite quantum dots composed of different halogens will cause halogen migration, thereby affecting the application. Researchers use ligand modification, inorganic coating and doping at A site, B site and X site to improve the stability of quantum dots, but the above methods are complex and difficult to popularize. The method of using polymer microspheres to encapsulate perovskite quantum dots not only improves the stability of perovskite quantum dots, but also has a simple preparation process and easy-to-obtain raw materials. However, the stability of the polymer-encapsulated perovskite quantum dots still needs to be further improved.

[0004] The use of fluorine-containing polymers to encapsulate perovskite quantum dots not only does not destroy the fluorescence effect, but also has better hydrophobicity, thus enhancing the stability of the quantum dots. The preparation process is simple, and the raw materials are easy to obtain. Based on this, the present application uses fluorinated cross-linked polymer microspheres to encapsulate perovskite quantum dots to protect the quantum dots from damage by the external environment and has excellent water resistance. SUMMARY

[0005] To solve the above problems, the present application provides a preparation method of fluorinated cross-linked microspheres coated perovskite quantum dot powder, which has a simple preparation process, simple raw materials and excellent water resistance of the prepared composite powder.

[0006] The technical scheme adopted by the present application to solve the above technical problems is as follows:

[0007] A preparation method of fluorinated cross-linked microspheres coated perovskite quantum dot powder, comprising the following steps:

[0008] (1) A certain amount of monomer A, polyvinylpyrrolidone, solvent are weighed and added into a reaction container, after the temperature is raised to 60-80°C under nitrogen atmosphere, an initiator is added; 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 feeding ratio of the monomer A, polyvinylpyrrolidone, solvent, initiator is 4:0.7-1.:60-100:0.04-0.06;

[0009] (2) After reacting for 60-120 min, a crosslinking agent, a fluorine-containing monomer, a monomer B and a solvent are added, and the reaction is continuously carried out, after the reaction is completed, washing, filtering and drying are carried out to obtain fluorinated crosslinked microspheres; the crosslinking agent is selected from at least one of divinylbenzene, ethylene glycol dimethacrylate, diisocyanate, the fluorine-containing monomer is selected from at least one of dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, trifluoroethyl acrylate, hexafluorobutyl acrylate, the monomer B is the same as the monomer A; the feeding 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;

[0010] (3) A certain amount of fluorinated crosslinked microspheres are weighed and added into a perovskite quantum dot solution with a concentration of 2-5wt%, swelling is carried out, after the swelling is completed, centrifugation is carried out, n-hexane is added to the precipitate obtained by centrifugation for shrinkage, after centrifugation, drying is carried out in a vacuum oven to obtain perovskite quantum dot powder coated with fluorinated crosslinked microspheres; the feeding ratio of the fluorinated crosslinked microspheres to the perovskite quantum dot solution is 1g:8-12mL.

[0011] As a preferred, the initiator is azobisisobutyronitrile, azobisisoheptyl nitrile or dibenzoyl peroxide.

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

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

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

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

[0016] In the preparation method of the fluorinated cross-linked microsphere coated perovskite quantum dot powder provided by the application, after the perovskite quantum dots are encapsulated by the fluorinated cross-linked 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 application has the beneficial effects that:

[0018] (1) The perovskite quantum dots are encapsulated by fluorine-containing polymer cross-linked microspheres, the chain structure of the polymer is opened by using a good solvent, so that the perovskite fluorescent nanoparticles enter the inside of the microspheres under the condition of concentration difference, and the external hydrophobicity makes the perovskite quantum dots immune to the damage of external water.

[0019] (2) The fluorine-containing polymer cross-linked microspheres prepared by the application can improve the stability of the perovskite quantum dots in water while retaining the fluorescence performance;

[0020] (3) The fluorine-containing polymer cross-linked microspheres of the perovskite quantum dots have high safety and high water resistance. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a comparison chart of the fluorinated cross-linked microsphere coated perovskite quantum dots prepared in Example 1 of the application under natural light (a) and 365 nm ultraviolet light (b);

[0022] Figure 2 is a scanning electron microscope chart of the fluorinated cross-linked microsphere coated perovskite quantum dots prepared in Example 2 of the application;

[0023] Figure 3 is a photo of the fluorinated cross-linked microsphere coated perovskite quantum dots prepared in Example 4 of the application changing in water under 365 nm ultraviolet light with time.

[0024] Figure 4 is a chart of the fluorescence intensity of the pure PMMA coated CsPbBr3 quantum dots prepared in Comparative Example 1 and the fluorinated cross-linked microsphere coated perovskite quantum dots prepared in Example 1 changing in water with time.

[0025] Figure 5 is a chart of the fluorescence intensity of the CsPbBr3 quantum dot toluene solution and the fluorinated cross-linked microsphere coated perovskite quantum dots prepared in Example 1. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, purposes and effects achieved by the application easy to understand, the application is specifically described below in combination with examples and drawings.

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

[0028] The perovskite quantum dots used in the embodiments of the present application are CsPbBr3 quantum dots, which are obtained by a hot injection method, and the specific preparation steps are as follows:

[0029] (1) 0.407 g of cesium carbonate powder, 1.25 mL of OA, and 20 mL of OED were added to a 50 mL three-necked flask, and the temperature was raised to 120°C under a nitrogen atmosphere. After continuous stirring for 1 h, the temperature was raised to 150°C until the solution became transparent and clear to prepare a cesium oleate precursor.

[0030] (2) 5 mL of OED liquid and 0.069 g of lead bromide powder were added to a 50 mL three-necked flask, and the temperature was raised to 120°C under a nitrogen atmosphere. Then 0.5 mL of OA and OAM were added respectively. After the powder disappeared, the temperature was raised to 160°C, and 0.4 mL of the preheated cesium oleate was added. After 5 s, the obtained quantum dot solution was cooled in an ice water bath to obtain a quantum dot precipitate 0.4 g. The obtained quantum dots were stored in 12.5 g of solvent (solvent: toluene, p-xylene, or ethyl acetate), and the concentration of the CsPbBr3 quantum dots was 3.1 wt%. The fluorescence intensity of the CsPbBr3 quantum dot toluene solution with a concentration of 3.1 wt% is shown in Figure 5 .

[0031] Example 1

[0032] The present embodiment provides a preparation method of fluorinated cross-linked microspheres coated perovskite quantum dot powder, which comprises the following steps:

[0033] (1) 4 g of methyl methacrylate, 0.9 g of polyvinylpyrrolidone, 40 g of water, and 40 g of ethanol were weighed and added to a 250 mL three-necked flask. Under a nitrogen atmosphere, the temperature was raised to 70°C, and then 0.06 g of azobisisobutyronitrile was added.

[0034] (2) After 1.5 h, 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 were added, and the reaction was continued for 8 h. After the reaction was completed, the cross-linked microspheres were washed, filtered, and dried.

[0035] (3) 1 g of cross-linked microspheres was weighed and added to 10 mL of CsPbBr3 quantum dot toluene solution, and swelling was performed for 5 h. After swelling was completed, centrifugation was performed, and n-hexane was added to the precipitate obtained by centrifugation to shrink. After centrifugation, the fluorinated cross-linked microspheres coated perovskite quantum dot powder was dried in a vacuum oven. The photos of the fluorinated cross-linked microspheres coated perovskite quantum dots prepared in Example 1 under natural light and 365 nm ultraviolet light are shown inFigure 1 The fluorescence intensity of the fluorinated cross-linked microspheres coated perovskite quantum dot powder is shown in Figure 5 .

[0036] Example 2

[0037] The present embodiment provides a preparation method of fluorinated cross-linked microspheres coated perovskite quantum dot powder.

[0038] (1) The experimental device and operation are the same as in Example 1, and 4.0 g of methyl methacrylate is replaced with 4.0 g of styrene, and 0.06 g of azobisisoheptane is replaced with 0.06 g of azobisisobutyronitrile in step (1).

[0039] (2) The experimental device and operation are the same as in Example 1, and 1 g of EDGMA is replaced with 1 g of divinylbenzene, 0.8 g of trifluoroethyl methacrylate is replaced with 0.8 g of dodecafluoroheptyl methacrylate, and 2 g of methyl methacrylate is replaced with 2 g of styrene in step (2).

[0040] (3) The experimental device and operation are the same as in Example 1, and 10 mL of CsPbBr3toluene solution is replaced with 10 mL of CsPbBr3p-xylene solution in step (3).

[0041] (4) The experimental device and operation are the same as in Example 1, and the swelling time of 5 h in step (3) is replaced with 8 h.

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

[0043] Example 3

[0044] The present embodiment provides a preparation method of fluorinated cross-linked microspheres coated perovskite quantum dot powder.

[0045] (1) The experimental device and operation are the same as in Example 1, and 4.0 g of methyl methacrylate is replaced with 4.0 g of butyl acrylate, and 0.06 g of azobisisoheptane is replaced with 0.06 g of p-benzoyl peroxide in step (1).

[0046] (2) The experimental device and operation are the same as in Example 1, and 1 g of EDGMA is replaced with 1 g of diisocyanate, 0.8 g of trifluoroethyl methacrylate is replaced with 0.8 g of hexafluorobutyl acrylate, and 2 g of methyl methacrylate is replaced with 2 g of butyl acrylate in step (2).

[0047] (3) The experimental device and operation are the same as in Example 1, and 10 mL of CsPbBr3toluene solution is replaced with 10 mL of CsPbBr3ethyl acetate solution in step (3).

[0048] (4) The experimental apparatus and operation are the same as in Example 1, and the swelling time in step (3) is changed from 5 h to 3 h.

[0049] Example 4

[0050] The present example provides a method for preparing fluorinated cross-linked microspheres coated perovskite quantum dot powder.

[0051] (1) The experimental apparatus and operation are the same as in Example 1, and in step (1), 4.0 g of methyl methacrylate is changed to 4.0 g of styrene, and 0.06 g of azobisisoheptane is changed to 0.06 g of p-dibenzoyl peroxide.

[0052] (2) The experimental apparatus and operation are the same as in Example 1, and in step (2), 1 g of EDGMA is changed to 1 g of divinylbenzene, 0.8 g of trifluoroethyl methacrylate is changed to 0.8 g of hexafluorobutyl acrylate, and 2 g of methyl methacrylate is changed to 2 g of styrene.

[0053] (3) The experimental apparatus and operation are the same as in Example 1, and in step (3), 10 mL of CsPbBr3toluene solution is changed to 10 mL of CsPbBr3p-xylene solution.

[0054] (4) The experimental apparatus and operation are the same as in Example 1, and the swelling time in step (3) is changed from 5 h to 10 h. The obtained fluorinated cross-linked microspheres coated perovskite quantum dot powder is placed in water, and every time interval, it is photographed under ultraviolet light in a dark environment to record the change of the fluorescence intensity of the fluorinated cross-linked microspheres coated perovskite quantum dot powder. Figure 3 .

[0055] Comparative Example 1

[0056] The present comparative example provides a method for preparing non-fluorinated cross-linked microspheres coated perovskite quantum dot powder, comprising the following steps:

[0057] (1) 4 g of methyl methacrylate, 0.9 g of polyvinylpyrrolidone, 40 g of water and 40 g of ethanol are weighed and added into a 250 mL three-necked flask, and 0.06 g of azobisisobutyronitrile is added after the temperature is raised to 70°C under a nitrogen atmosphere;

[0058] (2) After 1.5 h, 1 g of ethylene glycol dimethacrylate, 2 g of methyl methacrylate, 20 mL of ethanol and 20 mL of water are added, and the reaction is continued for 8 h. After the reaction is completed, the cross-linked microspheres are washed, filtered and dried;

[0059] (3) 1 g of cross-linked microspheres is weighed and added into 10 mL of quantum dot toluene solution, and swelled for 5 h. After the swelling is completed, centrifugation is performed, n-hexane is added to the precipitate obtained by centrifugation for shrinkage, and after centrifugation, the non-fluorinated cross-linked microspheres coated perovskite quantum dot powder is dried in a vacuum oven.

[0060] The non-fluorinated crosslinked microspheres-coated perovskite quantum dot powder prepared in Comparative Example 1 and the fluorinated crosslinked microspheres-coated perovskite quantum dot powder prepared in Example 1 were respectively put into water and the fluorescence intensity measured using a fluorescence spectrophotometer was recorded at intervals of time to obtain Figure 4 .

Claims

1. A method for preparing a fluorinated cross-linked microsphere-coated perovskite quantum dot powder, characterized by: The preparation method comprises the following steps: (1) weigh a proper amount of monomer A, polyvinylpyrrolidone, solvent and add them into a reaction container, then raise the temperature to 60-80°C under nitrogen atmosphere, and then add 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 feeding ratio of the monomer A, polyvinylpyrrolidone, solvent and initiator is 4:0.7-1:60-100:0.04-0.06; (2) after reacting for 60-120 min, add a crosslinking agent, a fluorine-containing monomer, a monomer B and a solvent, and continuously carry out the reaction, then after the reaction is completed, carry out washing, filtering and drying 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 the monomer B is the same as the monomer A; the feeding mass ratio of the 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; (3) weigh the fluorinated crosslinked microspheres, add a perovskite quantum dot solution with a concentration of 2-5wt% into the fluorinated crosslinked microspheres, carry out swelling, centrifuge after the swelling is completed, add n-hexane to the obtained precipitate to shrink, and then dry in a vacuum oven to obtain perovskite quantum dot powder coated with fluorinated crosslinked microspheres; the feeding ratio of the fluorinated crosslinked microspheres to the perovskite quantum dot solution is 1g:8-12mL.

2. The production method according to claim 1, characterized by: The initiator is azobisisobutyronitrile, azobisisoheptyl nitrile or dibenzoyl peroxide.

3. The production method according to claim 1, wherein: The feeding mass ratio of the monomer A, crosslinking agent, fluorine-containing monomer and monomer B is 4:1:0.8:

2.

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

5. The production method according to claim 1, wherein: In step (3), the swelling time is 2-10h.

6. The production method according to claim 1, wherein: In step (3), the concentration of the perovskite quantum dot solution is 3-4wt%, and the feeding ratio of the fluorinated crosslinked microspheres to the perovskite quantum dot solution is 1g:10mL.

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