Following on the heels of remarkable lead halide perovskite optoelectronic materials, interest in lead-free perovskites has grown rapidly past decade. Double halides with general formula A2MIMIIIX6 (where A is a large monovalent cation site, MI univalent metal, MIII trivalent and X halide) represent one promising classes such these, iodides are particularly interesting since their band gaps exp...
