Though different fabrication approaches exist, two-step deposition is one of the main experimental techniques now used to make efficient, stable PSCs, especially on the industrial scale. The process involves first depositing lead iodide (PbI2) and then adding halide salts of monovalent cations such as methylammonium iodide (MAI) and formamidinium iodide (FAI) to convert it to perovskite.
Click here for original story, Low-temperature crystallization of phase-pure α-formamidinium lead iodide enabled by study
Source: Phys.org