Method for synthesizing metal halide perovskite single crystal material through chemical vapor transport

Abstract

The invention relates to the field of metal halide perovskite materials, in particular to a method for synthesizing a metal halide perovskite single crystal material through chemical vapor transport. The preparation method comprises the following steps: mixing and sealing metals (Pb, Bi, Sn, Sb and Ge), halide salts (NH4I, KI, AgI, KBr, MAI and FAI) and transport agents (elemental iodine, elemental bromine and KCl) in a quartz reactor; the method comprises the following steps: putting a quartz reactor into a tubular furnace, controlling the temperatures of two ends of the quartz reactor, enabling reactants to volatilize and decompose at a high-temperature reaction end and generate chemical reaction, further depositing and growing a metal halide perovskite single crystal material at a low-temperature growth end, and removing a transport agent by a vacuum heating or acid pickling method. The method is a non-solution method, different perovskite single crystal materials can be prepared by controlling reactant components and composition and controlling the reaction temperature and the temperature difference, and the method has the characteristics that the process is simple and easy to operate, and the obtained metal halide perovskite single crystal material is high in crystallization quality.

Description

Technical Field

[0001] The invention relates to the field of metal halide perovskite materials, and in particular to a method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport. Background Art

[0002] In recent years, metal halide perovskite materials have shown great application potential in the fields of solar cells and photodetectors due to their high carrier mobility, long exciton lifetime and diffusion length, and high light absorption coefficient. However, the preparation of metal halide perovskite materials, their properties, and the research on related devices are mostly limited to polycrystalline thin films. Polycrystalline metal halide perovskite films contain a large number of charge traps in the grain boundaries, which leads to serious non-radiative recombination of carriers and ion migration in the devices, which greatly limits their application in optoelectronic devices. Relatively speaking, single crystal materials have long-range order in structure and few defects inside the crystal, so they have lower charge trap density and higher optoelectronic performance. However, the preparation of perovskite single crystal materials is still limited to the solution method, which uses the difference in solubility of perovskite in solution at different temperatures to precipitate and grow single crystal materials. The controllability of the solution method is poor, and the obtained materials are often not pure phases, have many defects, and have low crystal quality.

[0003] "Chemical vapor transport" is also known as chemical reaction assisted sublimation method, which is generally a method of volatilizing substances and causing chemical reactions by heating and other conditions, and then transporting them to a location with lower temperature for crystallization and growth of single crystal materials. The present invention uses this chemical vapor transport method to place different metals, transport agents and corresponding halide precursor salts at the high-temperature reaction end, and achieves controllable growth of metal halide perovskite single crystal materials at the low-temperature growth end by regulating temperature, temperature difference and time. This method has the characteristics of simple equipment and high single crystal quality, and the reaction is carried out in a closed environment, and the generated single crystal material has very few impurities. Summary of the invention

[0004] The purpose of the present invention is to provide a method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport. The metal halide perovskite single crystal materials are prepared by the chemical vapor transport method, which can solve the problems of low purity and many defects of single crystal perovskite materials prepared by the commonly used solution method.

[0005] The technical solution of the present invention is:

[0006] A method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport, wherein the metal halide perovskite single crystal materials are prepared by a chemical vapor transport method, wherein the reactants are directly sealed in a quartz reactor, firstly heated to volatilize the reactants and cause a chemical reaction, and then transported to a location with a lower temperature to crystallize and form a single crystal material.

[0007] The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport, the specific process of preparing metal halide single crystal material by chemical vapor transport method is: first, reactant metal, halide salt and transport agent are mixed and sealed in a quartz reactor; then the quartz reactor is placed in a tubular furnace, and the temperature at both ends of the quartz reactor is controlled to make the reactant volatilize and chemically react at the high-temperature reaction end, and then deposit and grow the metal halide perovskite single crystal material at the low-temperature growth end; finally, the transport agent is removed by vacuum heating or pickling.

[0008] The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport uses Pb, Bi, Sn, Sb or Ge as the metal material, which sublimates at high temperature or sublimates after reacting with a transport agent, and the content of the metal material in the reactant is 20wt% to 38.6wt%.

[0009] The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport, the halide salt used is one or a mixture of two or more of NH4I, KI, AgI, KBr, MAI, FAI, which sublimates or decomposes under high temperature, and the content of halide in the reactant is 40wt% to 51.2wt%.

[0010] In the method for synthesizing metal halide perovskite single crystal material by chemical vapor transport, the transport agent used is elemental iodine, elemental bromine or KCl, and its content in the reactants is 10.2wt% to 40wt%.

[0011] The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport removes elemental iodine or elemental bromine by vacuum heating at a temperature of 60°C to 90°C for 12h to 48h; and removes KCl by soaking in hydroiodic acid or hydrochloric acid solvent for 10 to 30min.

[0012] The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport has a high temperature reaction end temperature of 450°C to 750°C, a low temperature growth end temperature of 200°C to 450°C, a temperature gradient between the high temperature reaction end and the low temperature growth end of 25 to 30°C / cm, and a reaction time of 72h to 168h.

[0013] The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport, the metal halide perovskite single crystal material is lead-based halide or environmentally friendly non-lead-based halide perovskite, the metal halide perovskite single crystal material is large single crystal or single crystal particles, all of which have high crystal quality.

[0014] The design concept of the present invention is:

[0015] Chemical vapor transport, also known as chemical reaction assisted sublimation, is a method of volatilizing substances and causing chemical reactions by heating and other conditions, and then transporting them to a location with a lower temperature for crystallization to generate single crystal materials. First, reactants such as metals (Pb, Bi, Sn, Sb, Ge), halide salts (NH4I, KI, AgI, KBr, MAI, FAI) and transport agents (elemental iodine, elemental bromine, KCl) are mixed and sealed in a quartz reactor. Then the quartz reactor is placed in a tube furnace to control the temperature at both ends of the quartz reactor. At this time, the reactants are at the high-temperature reaction end. Among them, metals such as Bi, Pb, Sn, Sb, Ge can be heated at the high-temperature reaction end and react with the transport agent to sublimate or sublimate and react with the transport agent to obtain halide metal salts. Halide salt precursors can also sublimate or decompose under high temperature. The volatilization and decomposition products of these halide metal salts and halide salt precursors will further undergo chemical reactions and be transported to the low-temperature growth end under the action of the transport agent, and then the metal halide perovskite single crystal material will be deposited and grown at the low-temperature growth end. Finally, the transport agents elemental iodine and elemental bromine are removed by vacuum heating, or the KCl transport agent is removed by acid washing. This method is carried out in a closed environment and is easy to control. Different perovskite single crystal materials can be prepared by adjusting the reactant components and composition and controlling the reaction temperature and temperature difference at both ends, as well as the reaction time.

[0016] The advantages and beneficial effects of the present invention are:

[0017] 1. The present invention develops a "chemical vapor transport" method for preparing metal halide perovskite single crystal materials, which is a non-solution method with the characteristics of simple process, easy operation, and high crystal quality of the obtained metal halide perovskite single crystal materials.

[0018] 2. The method of preparing metal halide perovskite by "chemical vapor transport" proposed in the present invention is carried out in a closed environment and is easy to control. Different perovskite single crystal materials can be prepared by adjusting the composition and composition of the reactants and controlling the reaction temperature and temperature difference at both ends, as well as the reaction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the "chemical vapor transport method" of the present invention for preparing metal halide perovskite single crystal materials.

[0020] Figure 2 Schematic diagram of the device for preparing perovskite single crystal materials by "chemical vapor transport method". In the figure, 1 is a tubular furnace, 2 is a quartz reactor, 3 is a high-temperature reaction end, and 4 is a low-temperature growth end.

[0021] Figure 3 This is a macroscopic photograph of the KBiI3 perovskite single crystal material prepared by the “chemical vapor transport method” in Example 1. DETAILED DESCRIPTION

[0022] In the specific implementation process, Figure 1 As shown, the present invention prepares metal halide perovskite single crystal material by the method of "chemical vapor transport", and the specific process is:

[0023] First, metals such as Pb, Bi, Sn, Sb, Ge, NH4I, KI, AgI, KBr, MAI, FAI, or a mixture thereof are mixed with reactants such as elemental iodine, elemental bromine or KCl transport agents and sealed in a quartz reactor; the content of the metal material is 20wt% to 38.6wt%, the content of the halide salt is 40wt% to 51.2wt%, and the content of the transport agent is 10.2wt% to 40wt%. Then, as Figure 2 As shown, a quartz reactor 2 is placed in a tubular furnace 1, so that the reactants volatilize, decompose and react chemically at the high temperature reaction end 3. The temperature of the high temperature reaction end 3 of the quartz reactor 2 is controlled to be 450℃~750℃, and the temperature of the low temperature growth end 4 is controlled to be 200℃~450℃, and the temperature gradient between the high temperature reaction end 3 and the low temperature growth end 4 is 25~30℃ / cm. After reacting for 72h~168h, the sample is cooled to room temperature and taken out, and then annealed at 60℃~90℃ in vacuum for 12h~48h to remove elemental iodine or elemental bromine, or soaked in an acidic solvent such as HI, HCl for 10~30min to remove KCl to obtain a large single crystal or single crystal particle of perovskite.

[0024] Below, the present invention is further described in detail by examples.

[0025] Example 1

[0026] In this embodiment, first, metal Bi, halide salt precursor KI and transport agent elemental iodine are mixed and sealed in a quartz reactor; wherein the content of metal Bi is 31wt%, the content of KI is 42.2wt%, and the content of elemental iodine is 26.8wt%. Then, the quartz reactor is placed in a tubular furnace, and the temperature of the high-temperature reaction end of the quartz reactor is controlled to be 600°C, and the temperature of the low-temperature growth end is 300°C. The temperature gradient between the high-temperature reaction end and the low-temperature growth end is 25°C / cm, so that metal Bi and I2 are sublimated and reacted at the high-temperature reaction end to generate BiI3, which further reacts with KI or its decomposition product to generate KBiI3. After reacting for 84 hours, the sample is cooled to room temperature and taken out, and then annealed in vacuum at 60°C for 12 hours to obtain perovskite single crystal particles. Figure 3 As shown, a large number of perovskite single crystal particles were obtained, with a particle size ranging from 1 mm to 30 mm, high crystal quality, and obvious metallic luster. The half-height width of the diffraction peak tested by XRD was less than 0.5°.

[0027] Example 2

[0028] The difference from Example 1 is that the halide salt precursor used is KBr, the transport agent is single substance Br2, the content of metal Bi in the mixture of metal Bi, halide salt and transport agent is 29wt%, the content of KBr is 42.2wt%, and the content of transport agent is 28.8wt%. The temperature of the high temperature reaction end of the quartz reactor is controlled to be 500°C, the temperature of the low temperature growth end is 200°C, the temperature gradient between the high temperature reaction end and the low temperature growth end is 28°C / cm, the reaction time is 72h, and finally, a large perovskite single crystal KBiBr3 is obtained by vacuum annealing at 90°C for 12h, with an area of ​​5mm×8mm and a thickness of 80μm, having high crystal quality, showing obvious metallic luster, and the half-height width of the diffraction peak tested by XRD is less than 0.5°.

[0029] Example 3

[0030] The difference from Example 1 is that the metal used is Sb, the halide salt precursor is NH4I, and in the mixture of metal Sb, halide salt and transport agent, the content of metal Sb is 35wt%, the content of NH4I is 40wt%, and the content of I2 transport agent is 25wt%. The temperature of the high temperature reaction end of the quartz reactor is controlled to be 600℃, the temperature of the low temperature growth end is 300℃, the temperature gradient between the high temperature reaction end and the low temperature growth end is 30℃ / cm, the reaction time is 96h, and finally, a large perovskite single crystal (NH4)SbI3 is obtained by vacuum annealing at 90℃ for 24h, with an area of ​​5mm×8mm and a thickness of 100μm, having high crystal quality, showing obvious metallic luster, and the half-height width of the diffraction peak tested by XRD is less than 0.5°.

[0031] Embodiment 4:

[0032] The difference from Example 3 is that the metal used is Sn, the transport agent is KCl, and in the mixture of metal Sn, halide salt and transport agent, the content of metal Sn is 32.5wt%, the content of NH4I is 40wt%, and the content of KCl transport agent is 27.5wt%. The temperature of the high temperature reaction end of the quartz reactor is controlled to be 700℃, the temperature of the low temperature growth end is 300℃, the temperature gradient between the high temperature reaction end and the low temperature growth end is 28℃ / cm, the reaction time is 96h, and finally the product is soaked in hydrochloric acid with pH=3 for 30min to remove the KCl transport agent, and a large perovskite single crystal (NH4)SnI3 is obtained, which has an area of ​​5mm×5mm and a thickness of 100μm, has high crystal quality, shows obvious metallic luster, and the half-height width of the diffraction peak tested by XRD is less than 0.5°.

[0033] Example 5

[0034] The difference from Example 1 is that the halide salt precursor used is a mixture of NH4I and AgI, the content of metal Bi in the mixture of metal Bi, halide salt and transport agent is 21.6wt%, the content of NH4I and AgI is 22wt% and 28wt% respectively, and the content of I2 transport agent is 28.4wt%. The temperature of the high temperature reaction end of the quartz reactor is controlled to be 650℃, the temperature of the low temperature growth end is controlled to be 200℃, the temperature gradient between the high temperature reaction end and the low temperature growth end is 30℃ / cm, the reaction time is 72h, and finally, a large perovskite single crystal (NH4)2AgBiI9 is ​​obtained by heating and annealing at 90℃ in vacuum for 12h, which has an area of ​​5mm×5mm and a thickness of 100μm, has high crystal quality, shows obvious metallic luster, and the half-height width of the diffraction peak tested by XRD is less than 0.5°.

[0035] The results of the embodiment show that metal halide perovskite single crystal materials are prepared by the "chemical vapor transport" method. This method first directly seals the reactants in a quartz reactor, evaporates the reactants and causes a chemical reaction by heating, and then transports them to a location with a lower temperature to crystallize into a single crystal material. Different perovskite single crystal materials can be prepared by controlling the composition and composition of the reactants and controlling the reaction temperature and temperature difference.

Claims

1. A method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport, characterized in that: Metal halide perovskite single crystal materials are prepared by a chemical vapor transport method. This method directly seals the reactants in a quartz reactor, first heats the reactants to volatilize and react chemically, and then transports them to a location with a lower temperature to crystallize and form a single crystal material.

2. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 1, characterized in that: The specific process of preparing metal halide single crystal materials by chemical vapor transport is as follows: first, the reactant metal, halide salt and transport agent are mixed and sealed in a quartz reactor; then the quartz reactor is placed in a tubular furnace, and the temperature at both ends of the quartz reactor is controlled so that the reactants evaporate and chemically react at the high-temperature reaction end, and then the metal halide perovskite single crystal material is deposited and grown at the low-temperature growth end; finally, the transport agent is removed by vacuum heating or pickling.

3. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 1 or 2, characterized in that: The metal material used is Pb, Bi, Sn, Sb or Ge, which sublimates under high temperature or sublimates after reacting with a transport agent, and the content of the metal material in the reactant is 20wt% to 38.6wt%.

4. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 1 or 2, characterized in that: The halide salt used is one or a mixture of two or more of NH4I, KI, AgI, KBr, MAI and FAI, which sublimates or decomposes under high temperature and has a content of 40wt% to 51.2wt% in the reactant.

5. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 1 or 2, characterized in that: The transport agent used is elemental iodine, elemental bromine or KCl, and its content in the reactant is 10.2wt% to 40wt%.

6. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 5, characterized in that: Remove elemental iodine or elemental bromine by vacuum heating at a temperature of 60°C to 90°C for 12h to 48h; remove KCl by soaking in hydroiodic acid or hydrochloric acid solvent for 10 to 30min.

7. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 2, characterized in that: The temperature of the high-temperature reaction end is 450°C to 750°C, the temperature of the low-temperature growth end is 200°C to 450°C, the temperature gradient between the high-temperature reaction end and the low-temperature growth end is 25 to 30°C / cm, and the reaction time is 72h to 168h.

8. The method for synthesizing metal halide perovskite single crystal material by chemical vapor transport according to claim 1, characterized in that: The metal halide perovskite single crystal material is a lead-based halide or an environmentally friendly non-lead-based halide perovskite. The metal halide perovskite single crystal material is a large single crystal or a single crystal particle, both of which have high crystalline quality.

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