Investigating the iodide and bromide ion exchange in metal halide perovskite single crystals and thin films.

The anion exchange between MAPbX3 (X = I− or Br−) and MAX salts in a solution environment is investigated. We find that I− can enter MAPbBr3 single crystals (SC) in millimeter scale, while Br− can only penetrate the surface of MAPbI3 SC in a micrometer scale. Due to the lattice variation, the reaction is partially reversible. [ABSTRACT FROM AUTHOR]