Study On Preparation And Properties Of Perovskite Single Crystal

With the rapid development of economy,the world’s energy problem began to emerge.Oil,coal,natural gas and other traditional fossil energy is drying up.Development and use of alternative energy sources have become more and more important.The efficiency of perovskite solar cell has been notarized to 20%in just a few years.The research on the perovskite material is numerous at present.However,there are few studies on the properties of the band gap,carrier concentration and carrier lifetime of perovskite.In this paper,through the preparation of large-size perovskite single crystal,the photoelectrical properties of samples were analyzed by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),UV-Vis absorption spectroscopy(UV-Vis),Photoluminescence spectroscopy(PL),time-resolved PL(TRPL),X-ray photoelectron spectroscopy(XPS),Dark injection space charge limited current(DI SCLC).The main contents and results are as follows:(1)The single crystal of CH3NH3PbI3 were prepared by reverse temperature crystallization method.The maximum size of the grown crystal is 1 cm.The crystal structure belongs to tetragonal crystal.Threshold absorption wavelength is 800 nm.The band gap was 1.49 eV,the lifetime of carrier is 11.71 ns and the trap states of hole carrier is about 3 ×1010cm-3.In addition,(CH3NH3)3Bi2I9 single crystal was prepared by reverse temperature crystallization method.The maximum size of the crystal was about 7 mm.Threshold absorption wavelength is 650 nm.The width of band gap is about 1.96 eV.The valence of bismuth element is +3.The trap states of hole carrier is about 3 × 1011 cm-3.(2)CH3NH3Pb1-xBixI3 monocrystal solid solution with different Bi concentrations was prepared by reverse temperature crystallization.The crystal structure of single crystal changed with different Bi concentration.The lattice constant becomes smaller.The single-crystal solid solution with 20%Bi concentration has the largest light absorption range and the minimum band gap.(3)The Cs3Bi2I9 single crystal was prepared by the bottom crystallization method.The size of crystal is about 5 mm.The optimal growth temperature of Cs3Bi2I9 single crystal was 100℃ and the optimum solvent was dimethyl sulfoxide.Its crystal structure is hexagonal structure.The valence of bismuth element is +3.Threshold absorption wavelength is 650 nm.Its absorption performance in the ultraviolet and visible spectral regions is lower than that of the organic-inorganic hybrid perovskite((CH3NH3)3Bi2I9).It is a lead-free low toxicity perovskite material.