CN110862103B

CN110862103B - High-efficiency synthetic Cs2AgBr3Method for preparing lead-free inorganic perovskite

Info

Publication number: CN110862103B
Application number: CN201911223765.0A
Authority: CN
Inventors: 解仁国; 郭雪源; 张资序; 汪大洋; 杨文胜
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2019-12-03
Filing date: 2019-12-03
Publication date: 2021-07-06
Anticipated expiration: 2039-12-03
Also published as: CN110862103A

Abstract

The invention relates to a high-efficiency synthetic Cs₂AgBr₃A method for preparing lead-free inorganic perovskite belongs to the technical field of semiconductor nano material preparation. Firstly, cesium bromide and silver bromide are mixed according to a molar ratio of 2:1, then tri-n-octylphosphonium is added for grinding, the mixture is gradually hardened from fluffy faint yellow powder and attached to the wall of a container, the faint yellow powder is gradually changed into white powder along with the grinding, the grinding process is monitored by a 302nm ultraviolet lamp, and the grinding is stopped when the brightness of a product is not increased any more; the obtained product is subjected to heat treatment in a vacuum oven for 3 hours at the temperature of 80-300 ℃, and then is subjected to freezing treatment for 1-3 hours at the temperature of-10 ℃ to-50 ℃ to obtain Cs with improved fluorescence yield₂AgBr₃A non-lead all-inorganic perovskite. The method has the advantages of short time consumption, simple operation and suitability for large-scale production.

Description

High-efficiency synthetic Cs2AgBr3Method for preparing lead-free inorganic perovskite

Technical Field

The invention belongs to the technical field of semiconductor nano material preparation, and particularly relates to high-efficiency and high-purity all-inorganic non-lead perovskite Cs₂AgBr₃The preparation method of (1).

Background

The lead-calcium-titanium halide ore has good defect tolerance and arouses wide research interest in the field of luminescence. Lead perovskite halide has become the most promising photoelectric material, and due to its unique properties such as high absorption coefficient, long carrier diffusion length and low processing cost, different photoelectric devices designed based on lead perovskite halide have been successfully realized, including solar cells, light emitting diodes and lasers, and ultraviolet photodetectors. Despite these excellent properties of lead halide perovskite, the high toxicity and inherent instability of lead are two major problems with halide perovskites. On the premise of ensuring excellent performance, the replacement of lead by low-toxicity or non-toxic metal has important significance. Currently in perovskite, Sn²⁺Has been used to replace Pb²⁺. However, Sn²⁺The positive ions are easily oxidized due to the high energy 5s orbit, so that the corresponding tin-based perovskite is extremely unstable in the atmospheric environment. The variable-valence substitution of lead is the focus of attention of researchers, and at present, the variable-valence substitution of lead is mainly divided into two types, namely, two M types^ⅢA valence metal ion substitution and an M^ⅠA sum of value M^ⅢAnd (4) replacing valence metal ions. The former forms A due to balancing charge₃B₂X₉The structure type structure, the existence of the structural defect greatly reduces the luminescent property; the double perovskite formed by the latter is generally indirect band gap, and the fluorescence intensity is low, so that the double perovskite is not suitable for being used as a light-emitting device.

Hul group reported synthetic Cs in a 2004 publication₂AgBr₃The article is based on Cs₂AgBr₃The conductive properties of (2) were studied and the optical properties of the substance were not reported. Therefore, the material is expected to be used as a substitute for the lead-perovskite halide luminescent material. The method for preparing Cs by high-temperature solid-phase melting is adopted in the literature₂AgBr₃. The specific method is that the cesium bromide and the silver bromide are fed according to the molar ratio of 2:1, mixed and tabletted, put into a glass bottle, reacted for 2 weeks at 513K, and then slowly cooled to room temperature. The method has the defects of long reaction time and cooling time, long production period, high-temperature condition required by the reaction and high energy consumption. Most importantly, pure phase Cs cannot be obtained at any temperature by this method₂AgBr₃Cesium bromide is always present in the product, so that pure-phase Cs is desired₂AgBr₃And a subsequent treatment process is required, so that the utilization rate of raw materials is low, and the production process is complicated. This series of disadvantages severely impedes Cs₂AgBr₃Preparation and industrial production.

In conclusion, Cs₂AgBr₃The preparation method has certain limitation, and provides the Cs with mild reaction conditions, high raw material utilization rate, simple and time-saving operation, suitability for industrial large-scale production of pure phase and high fluorescence quantum yield₂AgBr₃The method of (A) has important significanceAnd (5) defining.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the problems in the background technology and provide a novel method which is simple and convenient to operate, short in time consumption, capable of being synthesized in large quantities at normal temperature and normal pressure and used for synthesizing pure-phase Cs₂AgBr₃Perovskite.

The technical problem of the invention is solved by the following technical scheme:

high-efficiency synthetic Cs₂AgBr₃Firstly, mixing cesium bromide and silver bromide according to a molar ratio of 2:1, adding tri-n-octylphosphine for grinding, wherein the using amount of the tri-n-octylphosphine is 30-100 uL for every 1mmol of silver bromide, gradually hardening the mixture from fluffy faint yellow powder and attaching the mixture to the wall of a container, gradually changing the faint yellow powder into white powder along with the grinding, monitoring the grinding process by using a 302nm ultraviolet lamp, and stopping when the brightness of a product is not increased any more; carrying out heat treatment on the obtained product in a vacuum oven at the temperature of 80-300 ℃ for 3 hours, and carrying out heat treatment on the obtained white Cs₂AgBr₃The product is frozen at-10 to-50 ℃ for 1 to 3 hours to obtain Cs with improved fluorescence yield₂AgBr₃A non-lead all-inorganic perovskite.

The invention relates to a high-efficiency synthetic Cs₂AgBr₃In the method of the lead-free all-inorganic perovskite, in order to better improve the fluorescence efficiency of the product, the dosage of the tri-n-octylphosphine is preferably 60uL per 1mmol of silver bromide.

The invention relates to a high-efficiency synthetic Cs₂AgBr₃In the method of the lead-free all-inorganic perovskite, the heat treatment temperature is preferably 150 ℃ in order to better improve the fluorescence efficiency of the product.

The invention relates to a high-efficiency synthetic Cs₂AgBr₃In the method of the lead-free all-inorganic perovskite, in order to better improve the fluorescence efficiency of the product and ensure that the crystallization degree of the product is better, the product is frozen, and the preferred temperature of the freezing treatment is-30 ℃.

Has the advantages that:

the invention realizes pure-phase Cs for the first time by a mechanical grinding method₂AgBr₃The preparation method has the advantages of short time consumption, simple operation and suitability for large-scale production.

Drawings

FIG. 1 is Cs prepared in example 1₂AgBr₃Solid absorption spectrum of perovskite material.

FIG. 2 is Cs prepared in example 1₂AgBr₃Solid fluorescence emission spectra of perovskite materials.

FIG. 3 is Cs prepared in example 1₂AgBr₃Solid XRD spectrum of perovskite material

FIG. 4 is Cs prepared in example 1₂AgBr₃Photograph of perovskite material under irradiation of 302nm ultraviolet lamp

Detailed Description

Example 1:

placing 2mmol of cesium bromide, 1mmol of silver bromide, 60ul of tri-n-octylphosphonium and 25 agate balls with the diameter of 6mm into a 25ml agate tank, adjusting the alternating current frequency of a ball mill to 35Hz, at the moment, the rotating speed is 1050rad/min, mechanically grinding for 2 hours, gradually hardening the mixture from fluffy faint yellow powder to be attached to the wall of the agate tank, irradiating by using a 302nm ultraviolet lamp, finding that the fluorescence brightness of the product does not continuously increase, and carrying out heat treatment on the product in a vacuum oven at 150 ℃ for 2 hours. White Cs obtained after heat treatment₂AgBr₃Freezing the product at-30 ℃ for 2h, performing solid absorption analysis and fluorescence test on the product, wherein the absorption spectrum is shown in figure 1, the emission spectrum is shown in figure 2, the fluorescence efficiency is 40.3%, the XRD spectrum of the product is shown in figure 3, and as can be seen from figure 3, the Cs prepared by the method of example 1₂AgBr₃Is phase pure. The photo of the excited luminescence of the product under UV lamp (302nm) is shown in FIG. 4. This embodiment is the most preferred embodiment.

Example 2: the dosage of tri-n-octylphosphine in example 1 is changed from 60uL to 30uL, 50uL, 80uL and 100uL respectively, and other conditions are not changed, the fluorescence quantum efficiency of the product is 25.6%, 36.7%, 33.9% and 33.4% respectively, so that the optimal dosage of tri-n-octylphosphine is 60 uL.

Example 3: the temperature of the vacuum oven heat treatment in example 1 was changed from 150 ℃ to 80 ℃, 100 ℃, 200 ℃, 300 ℃, and the fluorescence quantum efficiencies of the products were 30.2%, 36.2%, 34.1%, 33.7%, respectively, so the optimum heat treatment temperature was 150 ℃.

Example 4:

other conditions were not changed in example 1, and the freezing temperature after the heat treatment was changed from-30 ℃ to-10 ℃, -20 ℃, -40 ℃, -50 ℃, and the fluorescence quantum efficiencies of the products were 28.7%, 30.4%, 35.2%, 33.5%, respectively, so that the optimum freezing treatment temperature was-30 ℃.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. High-efficiency synthetic Cs₂AgBr₃Firstly, cesium bromide and silver bromide are mixed according to a molar ratio of 2:1, then tri-n-octylphosphine is added for grinding, the dosage of the tri-n-octylphosphine is 60uL for every 1mmol of silver bromide, the mixture is gradually hardened from fluffy faint yellow powder and attached to the wall of a container, the faint yellow powder is gradually changed into white powder along with the grinding, the grinding process is monitored by a 302nm ultraviolet lamp, and the grinding is stopped when the brightness of a product is not increased any more; carrying out heat treatment on the obtained product in a vacuum oven at the temperature of 80-300 ℃ for 3 hours, and carrying out heat treatment on the obtained white Cs₂AgBr₃The product is frozen at-10 to-50 ℃ for 1 to 3 hours to obtain Cs with improved fluorescence yield₂AgBr₃A non-lead all-inorganic perovskite.

2. The highly potent synthetic Cs of claim 1₂AgBr₃Method for preparing lead-free inorganic perovskiteThe method is characterized in that the heat treatment temperature is 150 ℃.

3. The highly potent synthetic Cs of claim 1₂AgBr₃A method for producing a lead-free all-inorganic perovskite, characterized in that the temperature of the freezing treatment is-30 ℃.