Quantitative imaging of anion exchange kinetics in halide perovskites

Significance Fundamental understanding of chemical transformation mechanism in solid-state semiconductors can offer guidelines for engineering these materials with various functionalities. Microscopically resolving such transformation process on the single-particle level can provide a direct picture of the dynamics, but has always been challenging due to the deficiencies of characterization techniques and material dimensions. This work presents a unique design on realizing the quantitative imaging of anion exchange reaction kinetics in halide perovskites by taking advantage of their high and tunable photoluminescence and characteristic lattice dynamics, coupled with controllable chemical treatments and optical microscopic techniques. Our study on kinetically visualizing ion exchange behavior in solid-state materials could also inspire mechanistic insights into other phenomena in a broad context of physical science.