Hexagonal phase CsPbBr3Nanocrystalline and preparation method thereof
阅读说明：本技术 六方相CsPbBr3纳米晶及其制备方法 (Hexagonal phase CsPbBr3Nanocrystalline and preparation method thereof ) 是由 房永征 陈鹏 刘玉峰 房诗玉 杨永阁 张娜 赵国营 侯京山 于 2019-09-30 设计创作，主要内容包括：本发明涉及一种六方相CsPbBr_3纳米晶的制备方法,将溴化铅粉末均匀分散于N,N-二甲基甲酰胺溶液中,水浴条件下搅拌使溴化铅粉末完全溶解得到溴化铅前驱体溶液；将溴化铯粉末均匀分散于无水乙醇溶液中,水浴条件下搅拌使溴化铯粉末完全溶解得到溴化铯前驱体溶液；室温、搅拌条件下,将溴化铅前驱体溶液和溴化铯前驱体溶液同时注入氯仿溶液,持续搅拌后静置处理,离心分离产物中的固体得到六方相CsPbBr_3纳米晶；N,N-二甲基甲酰胺溶液为油胺、油酸和N,N-二甲基甲酰胺的混合溶液；无水乙醇溶液为油胺、油酸和无水乙醇的混合溶液。与现有技术相比,本发明具有操作简单、元素化学计量比控制精确、无需高温或惰性气体保护装置等优点。(The invention relates to hexagonal phase CsPbBr 3 The preparation method of the nanocrystalline comprises the steps of uniformly dispersing lead bromide powder in an N, N-dimethylformamide solution, and stirring under the condition of water bath to completely dissolve the lead bromide powder to obtain a lead bromide precursor solution; uniformly dispersing cesium bromide powder in an absolute ethanol solution, and stirring in a water bath condition to completely dissolve the cesium bromide powder to obtain a cesium bromide precursor solution; simultaneously injecting lead bromide precursor solution and cesium bromide precursor solution into chloroform solution at room temperature under the condition of stirring, continuously stirring, standing, and centrifugally separating solids in the product to obtain hexagonal phase CsPbBr 3 A nanocrystal; the N, N-dimethylformamide solution is a mixed solution of oleylamine, oleic acid and N, N-dimethylformamide; the absolute ethyl alcohol solution is a mixed solution of oleylamine, oleic acid and absolute ethyl alcohol. Compared with the prior artCompared with the prior art, the method has the advantages of simple operation, accurate control of the stoichiometric ratio of elements, no need of a high-temperature or inert gas protection device and the like.)
1. Hexagonal phase CsPbBr3The preparation method of the nanocrystalline is characterized by comprising the following steps:
uniformly dispersing lead bromide powder in an N, N-dimethylformamide solution, and stirring under a water bath condition to completely dissolve the lead bromide powder to obtain a lead bromide precursor solution;
uniformly dispersing cesium bromide powder in an absolute ethanol solution, and stirring in a water bath condition to completely dissolve the cesium bromide powder to obtain a cesium bromide precursor solution;
simultaneously injecting lead bromide precursor solution and cesium bromide precursor solution into chloroform solution at room temperature under the condition of stirring, continuously stirring, standing, and centrifugally separating solids in the product to obtain the hexagonal phase CsPbBr3A nanocrystal;
wherein the N, N-dimethylformamide solution is a mixed solution of oleylamine, oleic acid and N, N-dimethylformamide; the absolute ethyl alcohol solution is a mixed solution of oleylamine, oleic acid and absolute ethyl alcohol.
2. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystalline is characterized in that in the lead bromide precursor solution, the ratio of the mass of the lead bromide powder to the volume of the N, N-dimethylformamide solution is 100-150 mg: 10-15 ml.
3. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystal is characterized in that in the cesium bromide precursor solution, the ratio of the mass of the cesium bromide powder to the volume of the absolute ethanol solution is 50-100 mg: 10-15 ml.
4. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystalline is characterized in that in the preparation process of the lead bromide precursor solution, the stirring time is 10-30min under the water bath condition; in the preparation process of the cesium bromide precursor solution, the stirring time is 30-60min under the water bath condition.
5. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystalline is characterized in that in the preparation process of the lead bromide precursor solution, the water bath temperature is 50-70 ℃; in the preparation process of the cesium bromide precursor solution, the water bath temperature is 60-70 ℃.
6. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystalline is characterized in that the dosage ratio of the lead bromide precursor solution, the cesium bromide precursor solution and the chloroform solution is as follows: 0.8-1.5 ml: 0.8-1.5 ml: 5-10 ml.
7. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystalline is characterized in that when the lead bromide precursor solution and the cesium bromide precursor solution are injected into the chloroform solution at the same time, the stirring speed is 800-1200 rmp/min.
8. Root of herbaceous plantThe hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystalline is characterized in that the standing treatment time is 5-10 days.
9. The hexagonal phase CsPbBr of claim 13The preparation method of the nanocrystal is characterized in that lead bromide powder and cesium bromide powder are respectively dispersed in the N, N-dimethylformamide solution and the absolute ethyl alcohol solution by ultrasound.
10. The hexagonal phase CsPbBr prepared by the preparation method of claim 13Nanocrystal characterized by the hexagonal phase CsPbBr3The nano-crystal is a flaky nano-crystal and is dispersed in toluene for storage.
Technical Field
The invention relates to CsPbBr3The field of perovskite nanocrystalline luminescent materials, in particular to hexagonal CsPbBr3Nanocrystal and a preparation method thereof.
Background
In recent years, all-inorganic perovskite quantum dots, which are new members of perovskite families, have attracted more and more attention of researchers due to the advantages of very narrow luminescence peaks, high quantum efficiency, good stability, simple preparation process, adjustable color and the like. Through the continuous efforts of researchers, all-inorganic perovskite quantum dots have been applied to solar cells, Light Emitting Diodes (LEDs), white light LEDs (wleds), lasers and other fields. With the continuous and deep scientific research, it is believed that the all-inorganic perovskite quantum dots become the core of the new generation of photoelectric materials.
Since the perovskite material has the advantages of easy synthesis, low cost, high absorption coefficient, long carrier diffusion distance and the like, the research on hot tide is promoted in the photovoltaic field, and the perovskite material becomes a good-hand 'star material'. In addition, the perovskite material also has high fluorescence quantum yield and a luminescent spectrum range which is easy to regulate and control through components, so that the perovskite material has a wide application prospect field in devices such as light-emitting diodes, solar cells, photoelectric detectors, solar cells, quantum dot lasers and the like.
At present, the synthesis methods of cesium-lead halogen perovskite quantum dots are many, in 2016, square CsPbBr of about 10nm is synthesized by professor once sea wave at room temperature3Quantum dots (adv. funct. mater.2016,26,2435), but do not yield bulky hexagonal nanoplates. In addition, the researchers have also adopted the chemical vapor deposition method (adv. Funct. Mater.2016,26, 6238-) The method obtains the large-volume square nanosheet, needs inert gas protection and high temperature of 600 ℃, and is not suitable for application and popularization.
Chinese patent CN109052457A discloses an inorganic perovskite nano-sheet and a preparation method thereof, the preparation steps are that CsBr and PbBr are mixed2Dissolving in N, N-dimethylformamide and stirring until no crystal particles exist; then adding oleic acid and oleylamine as organic ligands, continuing stirring until precipitates in the solution are separated out, removing the solution to obtain Cs4PbBr6And (4) precipitating. Mixing Cs4PbBr6Mixing the precipitate with water and standing to allow water and Cs4PbBr6The CsPbBr is obtained by the action3Nanosheets; however, CsPbBr prepared by the preparation method3The nano-sheet is square CsPbBr3The quantum dots also do not belong to hexagonal nanosheets.
Chinese patent CN 107312528A discloses a room temperature halogen-rich CsPbX3A method for preparing inorganic perovskite nanocrystals. Introducing halogenated amine on the basis of synthesizing inorganic perovskite nano crystal at the traditional room temperature, and adding a precursor solution added with the halogenated amine into a polar solvent to obtain CsPbX3(X ═ Cl, Br, I, or mixtures thereof) inorganic perovskite nanocrystals; however, the CsPbX prepared by the preparation method3The nano-sheet is square CsPbX3Quantum dots, also not hexagonal phase nanocrystals.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for preparing hexagonal phase CsPbBr at room temperature under the condition of no protective gas3A method of nanocrystalline; synthesized CsPbBr3The nanocrystalline is used as a photoelectric material.
The purpose of the invention can be realized by the following technical scheme:
hexagonal phase CsPbBr3The preparation method of the nanocrystalline comprises the following steps:
uniformly dispersing lead bromide powder in an N, N-dimethylformamide solution, and stirring under a water bath condition to completely dissolve the lead bromide powder to obtain a lead bromide precursor solution;
uniformly dispersing cesium bromide powder in an absolute ethanol solution, and stirring in a water bath condition to completely dissolve the cesium bromide powder to obtain a cesium bromide precursor solution;
simultaneously injecting lead bromide precursor solution and cesium bromide precursor solution into chloroform solution at room temperature under the condition of stirring, continuously stirring, standing, and centrifugally separating solids in the product to obtain the hexagonal phase CsPbBr3A nanocrystal;
wherein the N, N-dimethylformamide solution is a mixed solution of oleylamine, oleic acid and N, N-dimethylformamide;
the absolute ethyl alcohol solution is a mixed solution of oleylamine, oleic acid and absolute ethyl alcohol.
The experimental conditions of the method are room temperature, no inert gas is used for protection, and the whole reaction process only needs simple operations of stirring, standing and the like.
Different from the prior art that the mixed precursor solution of lead bromide and cesium bromide is prepared in one step, the method respectively prepares the precursors of lead bromide and cesium bromide, so that the pre-reaction of lead bromide and cesium bromide, which can cause the generation of tetragonal CsPbBr, can be avoided3And (4) a nanocrystal core, and hexagonal phase crystals cannot be obtained.
Wherein, in the lead bromide precursor solution, the ratio of the mass of the lead bromide powder to the volume of the N, N-dimethylformamide solution is 100-150 mg: 10-15 ml.
In the cesium bromide precursor solution, the ratio of the mass of the cesium bromide powder to the volume of the absolute ethanol solution is 50-100 mg: 10-15 ml.
In the preparation process of the lead bromide precursor solution, stirring for 10-30min under the water bath condition; in the preparation process of the cesium bromide precursor solution, the stirring time is 30-60min under the water bath condition.
In the preparation process of the lead bromide precursor solution, the water bath temperature is 50-70 ℃; in the preparation process of the cesium bromide precursor solution, the water bath temperature is 60-70 ℃.
The dosage ratio of the lead bromide precursor solution to the cesium bromide precursor solution to the chloroform solution is as follows: 0.8-1.5 ml: 0.8-1.5 ml: 5-10 ml.
And (3) simultaneously injecting the lead bromide precursor solution and the cesium bromide precursor solution into the chloroform solution, wherein the stirring speed is 800-1200 rmp/min.
The centrifugation speed of the product after standing is 6000-10000 rpm/min.
The standing treatment time is 5-10 days.
Lead bromide powder and cesium bromide powder were dispersed in the N, N-dimethylformamide solution and the anhydrous ethanol solution, respectively, by sonication.
The hexagonal phase CsPbBr prepared by the preparation method of the invention3The nanocrystal is sheet nanocrystal, hexagonal phase CsPbBr3The size of the nanocrystals was about 170nm and stored dispersed in toluene.
The standing time in the preparation process and the operation of respectively preparing precursors of lead bromide and cesium bromide are key parameters and steps, and tetragonal phase nanocrystals can be formed when the standing time is too short, for example, the inorganic perovskite nanosheet disclosed in the prior patent CN109052457A has the standing days of less than 5 days, the obtained product is tetragonal phase crystals, and regular hexagonal phase crystals cannot be obtained when the standing time is too long, so that hexagonal phase crystals with good appearance cannot be obtained when the standing time is too short or too long; in addition, as previously mentioned, the addition step of the present invention is important in that the separate preparation of the precursors of lead bromide and cesium bromide avoids the formation of tetragonal crystals.
Compared with the prior art, the invention has the following advantages:
(1) the preparation method successfully synthesizes the hexagonal CsPbBr3Nanocrystalline, compared to the tetragonal CsPbBr of the prior art3Nanocrystalline, hexagonal phase CsPbBr3The nanocrystalline has larger Stokes displacement, can avoid self-absorption effect caused by quantum dot agglomeration to a certain extent, and is more suitable for the field of solid illumination;
(2) the preparation process can be carried out at room temperature without inert gas protection, the reaction process only needs simple operations such as stirring and standing, and the like, and the method has the advantages of simple experimental conditions, high repeatability, easy operation, accurate control of element stoichiometric ratio and the like;
(3) the prepared hexagonal CsPbBr3The nanocrystal has excellent optical properties, and can be widely applied to the field of photoelectric materials, such as LEDs, photoelectric detectors, solar cells, quantum dot lasers and other devices.
Drawings
FIG. 1 shows a hexagonal phase CsPbBr of the present invention3TEM photograph of the nanocrystal;
FIG. 2 shows a hexagonal phase CsPbBr of the present invention3HRTEM photograph of the nanocrystal;
FIG. 3 shows a hexagonal phase CsPbBr of the present invention3Emission spectrum of the nanocrystal.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.