Competition between Oxygen Curing and Ion Migration in MAPbI3 Induced by Irradiation Exposure

Organometal halide perovskites (OHPs) have been considered as promising materials for light-emission devices. However, the factors influencing the luminescent property of OHPs are intricate. It is not only affected by the intrinsic crystalline quality but also depends on the surrounding environment. Here we demonstrate that the luminescence of CH3NH3PbI3 (MAPbI(3)) is governed by light-irradiation-induced oxygen curing and vacancy-mediated ion migration. The luminescence increases under continuous irradiation because of the curing of iodine vacancies (V-I) by oxygen. While, it decreases with enhanced ion migration, which would induce excess trap states. The existence of V-I is proved by low-temperature photoluminescence (PL) spectra, the hysteresis effect in J-V curves, and the excitation density dependence of the PL lifetime. Different oxygen environments and applied biases are employed to control the degree of oxygen curving and ion migration. These results provide a perception of the correlation of the complicated influencing factors affecting the luminescence of OHPs.