Characterization on crystal structure of CH3NH3PbIxCl3−x perovskite by variable temperature powder X-ray diffraction

In this work the CH3NH3PbIxCl3−x perovskite is obtained by applying vacuum-rotary evaporation procedure with a precursor solution of PbCl2 and CH3NH3I in dimethylformamide. Thermal gravimetric and differential thermal analysis (TG-DTA) and the variable temperature powder X-ray diffraction (in situ XRD) are employed to research the effect of thermal treatment on the decomposition and the crystal structure of perovskite. It is found that tetragonal to cubic phase transition in the typical perovskite disappears in mixed perovskite crystals because the stabilizing action of Cl. The excess Cl in the precursor leads to the intermediate structure CH3NH3PbCl3, and then transforms into CH3NH3PbI3 with temperature increasing.