Synthesis And Characterization Of Lead Halide Perovskite Single Crystal Materials

In recent years,lead halide perovskite?APbX₃?single crystal materials have become the focus of research because of their excellent optoelectronic properties,such as long carrier diffusion distance,low trap state density and wide light absorption range.Their application has been widely used in optoelectronic devices such as photodetectors,X-ray detectors and solar cells.At present,there are four major methods for preparing perovskite single crystals:solution temperature lowering?STL?,anti-solvent vapor assisted crystallization?AVC?,inverse temperature crystallization?ITC?,and melt crystallization.Among them,the ITC method has the fastest synthesis speed and the experimental process is relatively simple.In this paper,CH₃NH₃PbX₃?X=Br,I?single crystals with good performance were prepared by an improved ITC method.Above all methylamine,hydrobromic acid?hydroiodic acid?and lead bromide?lead iodide?were dissolved in N,N-dimethylformamide?DMF?or?-butyrolactone?GBL?to prepare CH₃NH₃PbI₃.According to X-ray powder diffraction?XRD?,photoluminescence spectroscopy?PL?,UV-Vis-NIR absorption spectrum,thermogravimetric analysis?TGA?and Raman spectroscopy,the prepared single crystals have high phase purity,and band gap is lower than the corresponding polycrystalline thin film materials.These single crystals began to decompose at more than 200°C?at 250°C for CH₃NH₃PbBr₃ and 230°C for CH₃NH₃PbI₃?.The final Raman spectrum revealed various types of vibration of the cations of the organic-inorganic hybrid CH₃NH₃PbBr₃ perovskite single crystal.Secondly,an all-inorganic perovskite CsPbBr₃ single crystal was synthesized.The XRD results show that the synthesized CsPbBr₃ is of high phase purity.Compared with the PL and UV curves of the organic-inorganic hybrid perovskite single crystals,it can be concluded that the optical properties of the metal halide perovskite single crystals mainly depend on the type of X halogen anions in APbX_3.Then TGA shows that the CsPbBr₃single crystal begins to decompose at 550°C,which is much higher than those of the organic-inorganic perovskite single crystals,which can be speculated that the thermal stability of lead halide perovskite APbX₃ single crystals is mainly dependent on the type of A cation.