Optical properties of CH3NH3PbI3 single crystal

CH3NH3PbI3 single crystals were successfully grown from HI solution by cooling method, and their structure were studied by X-ray diffraction. The Eg value of CH3NH3PbI3 single crystal determined by transmission spectrum was 1.51 eV. Low-temperature photoluminescence spectra of CH3NH3PbI3 single crystal show that a phase transition occurs at 160 K, the luminescence mechanism might be the intrinsic transition. And with the temperature rising, the “Varshni” trend is observed in CH3NH3PbI3 single crystal, indicating the change of Eg with temperature. Additionally, the Eg value obtained from the first principles is agree well with experimental result, and the DOS shows that Pb and I atoms have main contribution on the electric properties. Our results show that the CH3NH3PbI3 single crystals grown are of low trap density and have broad application prospects in the field of photoelectric devices. And low-temperature PL studies give supports on the direct-indirect character of CH3NH3PbI3 single crystal.