Highly crystalline methylammonium lead iodide films: Phase transition from tetragonal to cubic structure by thermal annealing

Herein, a very simple, solvent free, scalable, and single-step approach to prepare organometal halide perovskite powders via mechanochemical synthesis followed by the deposition of perovskite films by spin coating is reported. This work particularly deals with various parameters that influence the crystallization process and morphology (hyperbranched) of methylammonium lead iodide films. Moreover, the influence of growth temperature on the morphology and the transition from tetragonal to cubic structure are investigated. The mechanosynthesized perovskite provides hyperbranched morphology and crystalline films in a hexagonal shape and serves as a better precursor for the absorber layer in perovskite solar cells.