Real-time observation of ion migration in halide perovskite by photoluminescence imaging microscopy

The stability issue of organometal halide perovskite optoelectronic devices, e.g. the current-voltage -hysteresis effect and the degradation of the device performance under external light/electric field, are closely related to the ionic movement inside perovskite materials. However, our understanding of ionic properties is still at a relatively preliminary stage, and the detailed dynamic process of ionic movement in perovskite materials is controversial. Photoluminescence (PL) imaging microscopy, as a versatile real-time observation and characterization method, has become a powerful tool to explore the ionic movement in different material systems. This review firstly summarizes the development of PL imaging microscopy for ion migration characterization in perovskite materials. Secondly, combined with the wide-field PL imaging microscope, the dynamic process of ion migration in halide perovskite materials is further discussed. Thirdly, the observations of the degradation process and the ion migration suppression in different perovskite optoelectronic devices characterized by PL imaging microscopy are also introduced. This methodology is of significance for the deep understanding of the interaction between carriers/defect ions in perovskite materials, and provides guidance to further improve the stability and efficiency of perovskite optoelectronic devices.