High-Quality Mixed-Organic-Cation Perovskites from a Phase-Pure Non-stoichiometric Intermediate (FAI)1- x -PbI2 for Solar Cells

A high-quality mixed-organic-cation perovskite (MA)x (FA)1- x PbI3 is prepared from a phase-pure non-stoichiometric intermediate complex (FAI)1- x -PbI2 . The phase-pure (FAI)1- x -PbI2 probably facilitates homogenous nucleation and modulates the growth kinetics during the crystallization of (MA)x (FA)1- x PbI3 . This strategy can be expected to pave the way for the development of mixed-organic-cation perovskite solar cells.