Laser induced ion migration in all-inorganic mixed halide perovskite micro-platelet
Despite of the intensive research on the ion migration (IM) in organic-inorganic hybrid metal halide perovskites, much less is known for the irradiation effect on the IM in all-inorganic perovskites, especially for those of single crystals lacking the complicating grain boundaries. Herein, the real-time IM process and corresponding photoluminescence (PL) spectra induced by laser irradiation in all-inorganic CsPbBrxI(3-x) single crystal prepared by chemical vapor deposition (CVD) were investigated. We proposed that local electric field acts as a driving force for IM and confirmed that by applying a bias to an indium tin oxides (ITO)/perovskite/ITO configuration. According to the control experiments on CsPbBrxI(3-x) micro-platelets with and without Polymethyl Methacrylate (PMMA) coating, it is concluded that the vacancy defect on the single crystal surface is the main pathway for IM. Our work is important for understanding and controlling the light induced IM in all-inorganic perovskites.