Ralph Otmar Kusche

1 Introduction The study of halido metalates AxMyXz (A = inorganic or organic cation; M = metal cation; X = halide) has a long history, from the first investigations of these “double salts” more than a century ago by Wells,[1] to growing insights on their structural chemistry and ways to order and classify the observations made.[2] Current interest in this class of materials is driven by the success of lead halide perovskites as new semiconductor materials for solar cells,[3] light-emitting...