Mixed Group 14–15 Metalates as Model Compounds for Doped Lead Halide Perovskites

Abstract

Doping and alloying are valuable tools for modifying and enhancing the properties and performance of lead halide perovskites. However, the effects of heterovalent doping with Sb3+ and Bi3+ cations are still a matter of current investigation. Due to the different charge of the dopants compared to the constituting Pb2+ ions, a simultaneous creation of defects is unavoidable and the influence of these defects and the actual metal substitution become entangled. Herein, we present the first 14–15 iodido metalates, (BED)4PbE2I16 (BED=N‐benzylethylenediammonium; E=Sb (1), Bi (2)), which are model compounds for doped lead iodide perovskites and display surprisingly low band gaps of 2.01 (1) and 1.88 eV (2). Quantum chemical investigations show that this stems from a good electronic match between the PbI6 and EI6 units of the compounds. Our results provide a model system for doped perovskites, but also represent the first examples of a promising new class of metal halide materials.