The Role of Goldschmidt’s Tolerance Factor in the Formation of A 2 BX 6 Double Halide Perovskites and its Optimal Range

Vacancy‐ordered double perovskites is a new branch of lead‐free halide perovskites with properties promising for photovoltaic application. In this study, data about the crystal structure of 170 known A 2 BX 6 ( X = I, Br, Cl, F) are collected and analyzed to solve a question of applicability of the Goldschmidt’s tolerance factor and octahedral factor to double perovskites. It is found that Goldschmidt’s tolerance factor is applicable for double perovskites in analog with ABX 3 perovskites. Suggested optimal ranges of Goldschmidt’s factor expand the geometrical approach from ABX 3 perovskites to A 2 BX 6 double perovskites. The result is useful for up to 796 new full inorganic compounds having double‐perovskite structure and designing new hybrid organic–inorganic double perovskites.