Light-Induced Phase Segregation Evolution of All-Inorganic Mixed Halide Perovskites

Light-induced phase segregation in mixed halide perovskites is a major roadblock for commercialization of optoelectronics utilizing these materials. We investigate the phenomenon in a model material system consisting of only surfaces and the bulk of a single-crystalline-like microplate. We utilize environmental in-situ time-dependent photoluminescence spectroscopy to observe the bandgap evolution of phase segregation under illumination. This enables analysis of the evolution of the iodide-rich phase composition as a function of the environment (i.e., surface defects) and carrier concentration. Our study provides microscopic insights into the relationship among photocarrier generations, surface structural defects, and subsequently iodide ion migrations that result in the complex evolution of phase segregation. We elucidate the significance of surface defects with respect to the evolution of phase segregation, which may provide new perspectives for modulating ion migration by engineering of defects and carrier concentrations.

Automated summary

Light-induced phase segregation is a major obstacle for commercializing mixed halide perovskites in optoelectronics. We investigate this phenomenon in a model material system consisting of only surfaces and the bulk of a single-crystalline-like microplate. By utilizing environmental in-situ time-dependent photoluminescence spectroscopy, we observe the evolution of phase segregation under illumination and analyze the relationship between surface defects, carrier concentration, and the composition of iodide-rich phase. Our study provides microscopic insights into the complex evolution of phase segregation and highlights the importance of surface defects in modulating ion migration.