Anion Distribution, Structural Distortion, and Symmetry-Driven Optical Band Gap Bowing in Mixed Halide CsSnX Vacancy Ordered Double Perovskites.

Mixed anion compounds in the vacancy ordered perovskite structure were synthesized and characterized experimentally and computationally with a focus on compounds where A = Cs. Pure anion CsSnX compounds were formed with X = Cl, Br, and I using a room temperature solution phase method. Mixed anion compounds were formed as solid solutions of CsSnCl and CsSnBr and a second series from CsSnBr and CsSnI.