Study On Synthesis And Properties Of Single Crystal Perovskite

As an optical gain medium,metal halide perovskite has attracted extensive attention in photovoltaic field,optically pumped laser,radiation detection and other fields due to its advantages such as wide tunable band gap,high absorption coefficient,high photoluminescence quantum yield and high carrier mobility.However,the device application of perovskite crystals is still limited by many limitations.Firstly,due to the existence of grain boundaries,pores and defects in the polycrystalline perovskite,the mobility of ions and carriers will decrease.Second,at present,although have been successfully synthesized nanowires,nanoplates,polyhedron,voidcube and perovskite crystal,but long term or rod-shaped single crystal is rarely reported,some nanowires length only tens of microns,micro wire by the self-assembly method can achieve a few millimeters,but independent brittle microcrystal is difficult to assemble into practical laser equipment,Exposure to air can also affect its service life.In this work,the organic-inorganic hybrid perovskite single crystal fiber and inorganic perovskite single crystal fiber were prepared by solvent adjustment method using micro-capillary as template.The crystal growth mechanism and laser properties were studied and discussed.The specific work is as follows:（1）The perovskite single crystal fiber of methylamine lead bromide（MAPb Br₃）was prepared by using anti-solvent diffusion assisted crystallization method to investigate the growth regulation effect of organic solvents on the nanowires.（2）Centimeter metamine lead bromide perovskite single crystal was synthesized in hollow channel template.Organic-inorganic perovskite precursor solution was used to improve the solubilization of metamine bromide.A meniscus was formed at the edge of the gas-solid liquid interface through the limit of the template,and each meniscus had low equilibrium vapor pressure.The smaller evaporation area and lower vapor pressure together lead to lower evaporation rates and better management,which makes crystal growth more stable and controllable.By adjusting the concentration and temperature,single crystal fibers with a diameter of micron and a length of quasi centimeter were obtained.The laser properties and luminescence stability of single crystal were also discussed.（3）The crystal formation mechanism and optical properties of all inorganic Cesium lead bromide（CsPbBr₃）perovskite nanowires were discussed by combining spin-coating method and anti-solvent vapor phase assisted crystallization method.On this basis,the hollow channel template method was used to synthesize the quasi centimeter level all-inorganic CsPbBr₃perovskite single crystal fiber by adjusting the composition of the solvent.The laser properties of CsPbBr₃ single crystal fiber were preliminarily discussed.The experimental results show that the luminescence intensity of CsPbBr₃ single crystal fiber is 90%higher than that of CsPbBr₃ polycrystal fiber under the same low laser power.The average damage resistance threshold of Cs-Pb-Br single crystal fiber with the same diameter is 11350μJ/cm² higher than that of CsPbBr₃ polycrystal fiber,which is 5 times of the damage resistance threshold of MAPb Br₃ single crystal fiber.Moreover,CsPbBr₃ single crystal fiber has good luminescence stability.