阅读说明：本技术 一种铯铅卤无机钙钛矿量子点/透明高分子复合薄膜 (Cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film ) 是由 卢红霞 马德草 张艳艳 李明 刘建安 邵刚 范冰冰 王海龙 陈德良 许红亮 张锐 于 2019-09-20 设计创作，主要内容包括：本发明涉及一种铯铅卤无机钙钛矿量子点/透明高分子复合薄膜,属于全无机钙钛矿量子点的制备领域。该复合薄膜的制备包括以下步骤：1)将卤化铅、卤化铯、表面配体溶解于第一溶剂中,制备前驱体溶液；2)在搅拌下将前驱体溶液滴加到高分子溶液中,得到胶体溶液；利用胶体溶液制膜即可；高分子溶液由透明高分子材料溶解于第二溶剂中制成,所述第二溶剂不溶解铯铅卤量子点。本发明提供的铯铅卤无机钙钛矿量子点/透明高分子复合薄膜,实现了量子点的生成和高分子树脂原位封装,整个工艺流程简单,可重复性强,生产过程污染小,能耗少,原料来源广泛,可实现批量生产,具有良好的实用效果。(the invention relates to a cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film, and belongs to the field of preparation of all-inorganic perovskite quantum dots. The preparation method of the composite film comprises the following steps: 1) dissolving lead halide, cesium halide and a surface ligand in a first solvent to prepare a precursor solution; 2) dropwise adding the precursor solution into the polymer solution under stirring to obtain a colloidal solution; preparing a film by using a colloidal solution; the polymer solution is prepared by dissolving a transparent polymer material in a second solvent, wherein the second solvent does not dissolve the cesium-lead halogen quantum dots. The cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film provided by the invention realizes the generation of quantum dots and the in-situ encapsulation of polymer resin, has the advantages of simple whole process flow, strong repeatability, small pollution in the production process, low energy consumption, wide raw material source, realization of batch production and good practical effect.)

1. the cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film is characterized by being prepared by the method comprising the following steps:

1) Dissolving lead halide, cesium halide and a surface ligand in a first solvent to prepare a precursor solution;

2) Dropwise adding the precursor solution into the polymer solution under stirring to obtain a colloidal solution; preparing a film by using a colloidal solution; the polymer solution is prepared by dissolving a transparent polymer material in a second solvent, wherein the second solvent does not dissolve the cesium-lead halogen quantum dots.

2. The cesium-lead-halide inorganic perovskite quantum dot/transparent polymer composite thin film according to claim 1, wherein in the step 2), the volume ratio of the precursor solution to the polymer solution is (0.1-2) to (10-20).

3. The cesium-lead-halide inorganic perovskite quantum dot/transparent polymer composite film according to claim 1, wherein in the step 2), the temperature of the polymer solution is 60-90 ℃.

4. The cesium-lead-halide inorganic perovskite quantum dot/transparent polymer composite thin film according to claim 1, wherein in the step 1), the concentration of lead halide in the precursor solution is 0.01-0.05 mol/L; in the step 2), the concentration of the macromolecular solution is 0.01-1 g/mL.

5. The cesium lead halide inorganic perovskite quantum dot/transparent polymer composite film according to any one of claims 1 to 4, wherein in the step 1), the surface ligands are oleic acid and oleylamine, the volume ratio of the oleic acid to the oleylamine is (1.5-2.5):1, and the molar ratio of the oleic acid to the lead halide is (7-9): 1.

6. The cesium lead halide inorganic perovskite quantum dot/transparent polymer composite thin film according to any one of claims 1 to 4, wherein in step 1), the first solvent is N, N-dimethylformamide or dimethyl sulfoxide.

7. The cesium-lead-halide inorganic perovskite quantum dot/transparent polymer composite thin film according to any one of claims 1 to 4, wherein in the step 2), the second solvent is toluene or n-hexane.

8. The cesium-lead-halide inorganic perovskite quantum dot/transparent polymer composite thin film according to any one of claims 1 to 4, wherein in the step 2), the transparent polymer material is an ethylene-vinyl acetate copolymer.

Technical Field

The invention belongs to the field of preparation of all-inorganic perovskite quantum dots, and particularly relates to a cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film.

Background

₃Quantum Dots (QDs) are nano materials defined in a zero-dimensional quantum system and are particles limited in three-dimensional directions, and the quantum effect is a quantum size effect, a quantum confinement effect and a surface effect, when the particle size is smaller than a certain value, an electron level near a fermi level is changed into a discontinuous energy level, a phenomenon that an energy gap is widened occurs, electrons are in a bound state, excitons are easily formed, the specific surface area of the quantum dots is large, the surface activity is high, and defects are easily generated.

Compared with the traditional semiconductor quantum dot, the CsPbX ₃ quantum dot material has the following performance advantages that (1) the band gap width of a nanocrystal can be changed through halogen proportion adjustment, so that the luminescence of the nanocrystal can cover the whole visible light range, (2) the nanocrystal with different emission wavelengths can be excited by a single light source with the wavelength of 350-400 nm, (3) the color purity is high, the half-height width of an emission peak is only 12-42 nm and is much narrower than that of the traditional quantum dot and an organic dye, and (4) the defect tolerance is high, so that the fluorescence quantum yield can reach 100% under the condition of no passivation modification, the application foundation of the material in the fields of photoelectric devices, biomedicine and the like is laid.

The sensitivity of cesium-lead halide quantum dots to polar solvents directly affects its application. In a polar solvent (such as water) environment, the fluorescence characteristics of the quantum dots rapidly degrade for a short time until the fluorescence characteristics disappear. The solubility of the cesium-lead halogen perovskite in a polar solvent is high, and even a low dosage of the polar solvent can cause the decomposition of quantum dots, so that the structure of the quantum dots is damaged, and the luminescence of the quantum dots is influenced. Research shows that after the quantum dots are soaked in water for 3 hours, the fluorescence performance of the quantum dots is reduced by about 80%. In addition, when the perovskite quantum dots are in the air for a long time, the quantum dots are decomposed under the combined action of water and oxygen in the air, and the long-term stability of the perovskite quantum dots is seriously influenced.

The application publication number of CN108034391A of Chinese invention discloses a solar cell EVA (ethylene-vinyl acetate copolymer) packaging adhesive film material with a light conversion function and a preparation method thereof, wherein EVA is dissolved in dichloromethane to form a dichloromethane solution of EVA, cesium-lead halogen quantum dots are dispersed in an organic solvent to form a dispersion solution, the dispersion solution is added into the dichloromethane solution of EVA, a cross-linking agent is added for reaction, and then the reaction product is dried to form a film, so that the transparent light conversion adhesive film material is prepared.

The existing composite film material is prepared by mixing cesium-lead halide quantum dot dispersion liquid and EVA solution, in the preparation process, cesium-lead halide quantum dots undergo multiple stages of reaction generation, separation precipitation, redispersion and the like, the stability of the cesium-lead halide quantum dots is poor due to sensitivity of all-inorganic cesium-lead halide quantum dots to air, water and polar solvents, and the structures of the quantum dots are easy to damage in the multiple operation and transfer processes, so that the luminescence performance of a film product is poor.

Disclosure of Invention

The invention aims to provide a cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film to solve the problem that the luminescent performance of quantum dots is poor due to the fact that the quantum dot structure is easily damaged by an existing method.

In order to achieve the purpose, the technical scheme of the cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film is as follows:

A cesium-lead halogen inorganic perovskite quantum dot/transparent polymer composite film is prepared by the following steps:

1) Dissolving lead halide, cesium halide and a surface ligand in a first solvent to prepare a precursor solution;

2) dropwise adding the precursor solution into the polymer solution under stirring to obtain a colloidal solution; preparing a film by using a colloidal solution; the polymer solution is prepared by dissolving a transparent polymer material in a second solvent, wherein the second solvent does not dissolve the cesium-lead halogen quantum dots.

According to the cesium-lead-halogen inorganic perovskite quantum dot/transparent polymer composite film provided by the invention, a supersaturated recrystallization method is utilized to crystallize and precipitate cesium-lead-halogen quantum dots in a second solvent, the quantum dots are positioned in a network structure of polymer resin while being synthesized, and the resin wraps the quantum dots after drying to form the composite film material. The quantum dots obtained by the method of supersaturated recrystallization have small and uniform particle size, good dispersibility and good luminous performance, and the method realizes the generation of the quantum dots and the in-situ encapsulation of the polymer resin, and has the advantages of simple whole process flow, strong repeatability, small pollution in the production process, less energy consumption, wide raw material source, realization of batch production and good practical effect.

In order to promote the formation of the cesium-lead halogen quantum dots with small particle size, good dispersion and avoidance of agglomeration, preferably, in the step 2), the volume ratio of the precursor solution to the polymer solution is (0.1-2): 10-20.

In order to accelerate the rapid synthesis of the cesium-lead halogen quantum dots and promote the precipitation of a fine crystal structure, it is preferable that the temperature of the polymer solution in the step 2) is 60-90 ℃.

In order to further optimize the crystallization effect of the precursor solution in the polymer solution, preferably, in the step 1), the concentration of the lead halide in the precursor solution is 0.01-0.05 mol/L; in the step 2), the concentration of the macromolecular solution is 0.01-1 g/mL.

In order to achieve better passivation and stabilization effects, it is preferable that in step 1), the surface ligands are oleic acid and oleylamine, the volume ratio of oleic acid to oleylamine is (1.5-2.5):1, and the molar ratio of oleic acid to lead halide is (7-9): 1.

The first solvent may be capable of dissolving the lead halide, cesium halide and the surface ligand, and is preferably N, N-dimethylformamide or dimethylsulfoxide in view of raw material cost. The second solvent is preferably selected such that the smaller the solubility of the cesium-lead halide quantum dots, the better, and in step 2), the second solvent is toluene or n-hexane.

the choice of the polymer matrix is not particularly limited, and in order to make the film material have the characteristics of good water resistance, transparency and high flexibility, preferably, the transparent polymer material is ethylene-vinyl acetate copolymer (EVA). The cesium-lead halogen perovskite quantum dots are wrapped by EVA, so that the quantum dots can be prevented from contacting water and oxygen molecules in the air, the stability of the quantum dot film is improved, and related products are expected to have good application in the fields of white light LEDs, flexible display and the like.

Drawings

FIG. 1 is a TEM (a), HRTEM (b) and a size distribution diagram (c) of cesium-lead halide inorganic perovskite quantum dots obtained in example 1 of the present invention;

FIG. 2 is an XRD pattern of thin film materials of examples of the present invention and comparative examples;

FIG. 3 is a FT-IR chart of film materials of examples of the invention and comparative examples;

FIG. 4 shows SEM (a) and EDS (EDS Spectroscopy) spectra of the surface of the CsPbBr ₃/EVA film prepared in example 1, wherein the EDS spectra respectively show four elements, namely (b) C, (C) Cs, (d) Br and (e) Pb;

FIG. 5 is a Photoluminescence (PL) spectrum of thin film materials of examples of the present invention and comparative examples;

FIG. 6 is a full width at half maximum (FWHM) plot of thin film materials of examples and comparative examples of the present invention;

FIG. 7 is a PL spectrum of a composite film material of example 1 after different soaking times;

FIG. 8 is a graph of strength retention of the composite film material of example 1 of the present invention after various soaking times;

FIG. 9 is a PL spectrum of a composite thin film material of example 1 of the present invention after a long-term standing;

FIG. 10 is a graph showing the strength retention of the composite film material of example 1 of the present invention after a long-term storage.

Detailed Description

The following examples are provided to further illustrate the practice of the invention.

First, a specific embodiment of the cesium-lead halide inorganic perovskite quantum dot/transparent polymer composite film of the present invention