A method for chemical vapor transport synthesis of metal halide perovskite single crystal material

Abstract

The present application relates to the field of metal halide perovskite material, in particular to a method for chemical vapor transport synthesis of metal halide perovskite single crystal material. The preparation method comprises: mixing and sealing metal (Pb, Bi, Sn, Sb, Ge), halide salt (NH4I, KI, AgI, KBr, MAI, FAI) and transport agent (elemental iodine, elemental bromine, KCl) in a quartz reactor. The quartz reactor is placed in a tube furnace, and the temperature at both ends of the quartz reactor is controlled, so that the reactants volatilize, decompose and chemically react at the high-temperature reaction end, and then deposit and grow metal halide perovskite single crystal material at the low-temperature growth end, and the transport agent is removed by vacuum heating or acid washing. The method is a non-solution method, 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, and the method has the characteristics of simple process, easy operation, and high crystalline quality of the obtained metal halide perovskite single crystal material.

Description

Technical Field

[0001] This invention relates to the field of metal halide perovskite materials, specifically a method for synthesizing single-crystal metal halide perovskite materials via chemical vapor transport. Background Technology

[0002] In recent years, metal halide perovskite materials have shown great application potential in fields such as solar cells and photodetectors due to their high carrier mobility, long exciton lifetime and diffusion length, and high light absorption coefficient. However, research on the preparation, properties, and related devices of metal halide perovskite materials has been largely limited to polycrystalline thin films. Polycrystalline metal halide perovskite thin films contain a large number of charge traps at grain boundaries, leading to severe nonradiative recombination of carriers and ion migration in the devices, which greatly limits their application in optoelectronic devices. In contrast, single-crystal materials have long-range order in structure and fewer internal defects, thus exhibiting lower charge trap density and higher photoelectric performance. However, the preparation of perovskite single-crystal materials is still limited to solution methods, utilizing the difference in solubility of perovskite in solution at different temperatures to precipitate and grow single-crystal materials. Solution methods have poor controllability, and the materials obtained are often not pure phases, have many defects, and have low crystal quality.

[0003] "Chemical vapor transport," also known as chemical reaction-assisted sublimation, generally involves heating or other conditions to volatilize substances and induce a chemical reaction, followed by transport to a lower temperature location for crystallization and growth of single-crystal materials. This invention employs this chemical vapor transport method, placing different metals, transport agents, and corresponding halide precursor salts at a high-temperature reaction end. By controlling the temperature, temperature difference, and time, controllable growth of metal halide perovskite single-crystal materials is achieved at a low-temperature growth end. This method features simple equipment, high-quality single crystals, and the reaction is carried out in a closed environment, resulting in single-crystal materials with very few impurities. Summary of the Invention

[0004] The purpose of this invention is to provide a method for synthesizing metal halide perovskite single crystal materials using chemical vapor phase transport. This method can solve the problems of low purity and numerous defects in single crystal perovskite materials prepared by commonly used solution methods.

[0005] The technical solution of this invention is:

[0006] A method for synthesizing metal halide perovskite single crystal materials via chemical vapor transport is disclosed. The method involves directly sealing the reactants in a quartz reactor, first heating the reactants to volatilize and induce a chemical reaction, and then transporting them to a lower temperature location to crystallize and form single crystal materials.

[0007] The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport (CVT) involves the following steps: 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 tube furnace, and the temperatures at both ends of the reactor are controlled to allow the reactants to volatilize and undergo a chemical reaction at the high-temperature reaction end, thereby depositing and growing metal halide perovskite single crystal materials at the low-temperature growth end. Finally, the transport agent is removed by vacuum heating or acid washing.

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

[0009] The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport uses one or more of the halide salts selected from NH4I, KI, AgI, KBr, MAI, and FAI, which are sublimated or decomposed at high temperature, and their content in the reactants is 40wt% to 51.2wt%.

[0010] The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport uses elemental iodine, elemental bromine, or KCl as the transport agent, and the content of the agent in the reactants is 10.2 wt% to 40 wt%.

[0011] The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport involves removing elemental iodine or bromine by vacuum heating at a temperature of 60℃ to 90℃ for 12h to 48h, and removing 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℃~750℃, a low-temperature growth end temperature of 200℃~450℃, a temperature gradient between the high-temperature reaction end and the low-temperature growth end of 25~30℃ / cm, and a reaction time of 72h~168h.

[0013] The method for synthesizing metal halide perovskite single crystal materials via chemical vapor transport describes the use of lead-based halides or environmentally friendly non-lead-based halides as the metal halide perovskite single crystal materials. The metal halide perovskite single crystal materials are either large single crystal sheets or single crystal particles, all of which have high crystallinity.

[0014] The design concept of this invention is:

[0015] Chemical vapor transport (CVT), also known as chemical reaction-assisted sublimation, is a method that uses heating and other conditions to volatilize substances and induce chemical reactions, which are then transported to a lower temperature location for crystallization to form 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. The quartz reactor is then placed in a tube furnace, and the temperatures at both ends of the reactor are controlled. At this point, the reactants are at the high-temperature reaction end. Metals such as Bi, Pb, Sn, Sb, and Ge can be heated at the high-temperature reaction end and react with the transport agent before sublimation, or sublimation followed by reaction with the transport agent to obtain halide metal salts. The halide salt precursors can also sublimate or decompose under high temperature conditions. The volatilization and decomposition products of these halide metal salts and halide salt precursors undergo further chemical reactions and are transported to the low-temperature growth end under the action of a transport agent, where metal halide perovskite single crystals are deposited and grown. Finally, the transport agents elemental iodine and elemental bromine are removed by vacuum heating, or KCl is removed by acid washing. This method is carried out in a closed environment, making it easy to control. Different perovskite single crystal materials can be prepared by adjusting the composition of the reactants and controlling the reaction temperature and temperature difference at both ends, as well as the reaction time.

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

[0017] 1. This invention develops a "chemical vapor transport" method for preparing metal halide perovskite single crystal materials. It 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 for preparing metal halide perovskites by "chemical vapor transport" proposed in this invention is carried out in a closed environment, which is easy to control. Different perovskite single crystal materials can be prepared by adjusting the composition of the reactants and controlling the reaction temperature and temperature difference at both ends, as well as the reaction time. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation of metal halide perovskite single crystal materials using the "chemical vapor transport method" of this invention.

[0020] Figure 2 A schematic diagram of the apparatus for preparing perovskite single crystal materials by the "chemical vapor transport method". In the diagram, 1 is a tube 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 Implementation

[0022] In the specific implementation process, such as Figure 1 As shown, this invention prepares metal halide perovskite single crystal materials via a "chemical vapor transport" method. The specific process is as follows:

[0023] First, metals such as Pb, Bi, Sn, Sb, and Ge, halide salts of NH4I, KI, AgI, KBr, MAI, and FAI, or mixtures thereof, are mixed with reactants such as elemental iodine, elemental bromine, or KCl transport agent and then sealed in a quartz reactor. The content of the metal material is 20 wt%–38.6 wt%, the content of the halide salt is 40 wt%–51.2 wt%, and the content of the transport agent is 10.2 wt%–40 wt%. Then, as... Figure 2 As shown, a quartz reactor 2 is placed in a tube furnace 1, allowing the reactants to volatilize, decompose, and undergo a chemical reaction at the high-temperature reaction end 3. The temperature of the high-temperature reaction end 3 of the quartz reactor 2 is controlled at 450℃~750℃, and the temperature of the low-temperature growth end 4 is controlled at 200℃~450℃, with a temperature gradient of 25~30℃ / cm between the high-temperature reaction end 3 and the low-temperature growth end 4. After reacting for 72h~168h, the sample is cooled to room temperature and removed. It is then annealed under vacuum at 60℃~90℃ for 12h~48h to remove elemental iodine or elemental bromine, or soaked in acidic solvents such as HI or HCl for 10~30min to remove KCl, thus obtaining large perovskite single crystals or single crystal particles.

[0024] The present invention will now be described in further detail through examples.

[0025] Example 1

[0026] In this embodiment, firstly, metallic Bi, the halide salt precursor KI, and the transport agent elemental iodine are mixed and sealed in a quartz reactor; wherein the content of metallic Bi is 31 wt%, the content of KI is 42.2 wt%, and the content of elemental iodine is 26.8 wt%. Then, the quartz reactor is placed in a tube furnace, and the temperature of the high-temperature reaction end of the quartz reactor is controlled at 600°C, the temperature of the low-temperature growth end is 300°C, and the temperature gradient between the high-temperature reaction end and the low-temperature growth end is 25°C / cm. This allows metallic Bi and I2 to sublimate and react at the high-temperature reaction end to form BiI3, which further reacts with KI or its decomposition products to form KBiI3. After a reaction time of 84 hours, the sample is cooled to room temperature and removed, then annealed under 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 range of 1 mm to 30 mm. They have high crystal quality, exhibit obvious metallic luster, and the full width at half maximum (FWHM) of the diffraction peaks measured by XRD is 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 elemental Br2, and the content of metallic Bi, halide salt, and transport agent mixture is 29 wt%, KBr content is 42.2 wt%, and transport agent content is 28.8 wt%. The temperature of the high-temperature reaction end of the quartz reactor is controlled at 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 72 h, and finally, after vacuum annealing at 90°C for 12 h, a large perovskite single crystal KBiBr3 is obtained with an area of ​​5 mm × 8 mm and a thickness of 80 μm. It has high crystal quality, exhibits obvious metallic luster, and the full width at half maximum (FWHM) of the diffraction peak measured 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 the content of Sb, halide salt and transport agent in the mixture is 35wt%, NH4I is 40wt%, and I2 transport agent is 25wt%. The temperature of the high-temperature reaction end of the quartz reactor is controlled at 600℃ and 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, after vacuum annealing at 90℃ for 24h, a large perovskite single crystal (NH4)SbI3 is obtained with an area of ​​5mm×8mm and a thickness of 100μm. It has high crystal quality, exhibits obvious metallic luster, and the full width at half maximum (FWHM) of the diffraction peak measured by XRD is less than 0.5°.

[0031] Example 4:

[0032] The difference from Example 3 is that the metal used is Sn, and the transport agent is KCl. In the mixture of metal Sn, halide salt, and transport agent, the content of metal Sn is 32.5 wt%, the content of NH4I is 40 wt%, and the content of KCl transport agent is 27.5 wt%. The temperature of the high-temperature reaction end of the quartz reactor is controlled at 700°C, 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 28°C / cm, and the reaction time is 96 h. Finally, the product is soaked in hydrochloric acid with pH=3 for 30 min to remove the KCl transport agent, and large perovskite single crystals (NH4)SnI3 are obtained with an area of ​​5 mm × 5 mm and a thickness of 100 μm. It has high crystal quality, exhibits obvious metallic luster, and the full width at half maximum (FWHM) of the diffraction peaks measured by XRD is less than 0.5°.

[0033] Example 5

[0034] The difference from Example 1 is that the halide salt precursor used was a mixture of NH4I and AgI. In the mixture of metallic Bi, halide salt, and transport agent, the content of metallic Bi was 21.6 wt%, the contents of NH4I and AgI were 22 wt% and 28 wt%, respectively, and the content of I2 transport agent was 28.4 wt%. The temperature of the high-temperature reaction end of the quartz reactor was controlled at 650°C, the temperature of the low-temperature growth end was 200°C, the temperature gradient between the high-temperature reaction end and the low-temperature growth end was 30°C / cm, and the reaction time was 72 h. Finally, after vacuum annealing at 90°C for 12 h, large perovskite single crystals (NH4)2AgBiI9 were obtained, with an area of ​​5 mm × 5 mm and a thickness of 100 μm. They had high crystal quality, exhibited obvious metallic luster, and the full width at half maximum (FWHM) of the diffraction peaks measured by XRD was less than 0.5°.

[0035] The results of the examples show that metal halide perovskite single crystal materials can be prepared by the "chemical vapor transport" method. This method first directly seals the reactants in a quartz reactor, and then heats them to volatilize and undergo a chemical reaction. The reactants are then transported to a lower temperature location to crystallize and form single crystal materials. Different perovskite single crystal materials can be prepared by controlling the composition and structure of the reactants and controlling the reaction temperature and temperature difference.

Claims

1. A method for synthesizing metal halide perovskite single crystal materials via chemical vapor phase transport, characterized in that, Metal halide perovskite single crystal materials are prepared by chemical vapor transport method. This method directly seals the reactants in a quartz reactor, first heating the reactants to volatilize and undergo a chemical reaction, and then transporting them to a lower temperature location to crystallize and form single crystal materials. The specific process for preparing metal halide single crystal materials by chemical vapor transport method 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 tube furnace, and the temperature at both ends of the quartz reactor is controlled so that the reactants volatilize and undergo a chemical reaction at the high-temperature reaction end, and then metal halide perovskite single crystal materials are deposited and grown at the low-temperature growth end; finally, the transport agent is removed by vacuum heating or acid washing. The metallic materials used are Pb, Bi, Sn, Sb, or Ge, which sublimate under high temperature or after reacting with the transport agent, and their content in the reactants is 20 wt%~38.6 wt%. The halide salts used are one or more of NH4I, KI, AgI, KBr, MAI, and FAI, which sublimate or decompose at high temperatures, and their content in the reactants is 40 wt%~51.2 wt%. The high-temperature reaction end temperature is 450 ℃~750 ℃, the low-temperature growth end temperature is 200 ℃~450 ℃, the temperature gradient between the high-temperature reaction end and the low-temperature growth end is 25 ~30 ℃ / cm, and the reaction time is 72 h~168 h.

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

3. The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport according to claim 2, characterized in that, Elemental iodine or bromine is removed by vacuum heating at 60 ℃ ~ 90 ℃ for 12 h ~ 48 h; KCl is removed by soaking in hydroiodic acid or hydrochloric acid solvent for 10 ~ 30 min.

4. The method for synthesizing metal halide perovskite single crystal materials by chemical vapor transport according to claim 1, characterized in that, Metal halide perovskite single crystal materials are lead-based halides or environmentally friendly non-lead-based halide perovskites. Metal halide perovskite single crystal materials are either large single crystals or single crystal particles, all of which have high crystal quality.

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