The present invention relates to compounds of the formula (1) which are suitable for use in electronic devices, in particular organic electroluminescent devices, and to electronic devices, which comprise these compounds. ##STR00001##

The present invention relates to compounds of the formula (1) which are suitable for use in electronic devices, in particular organic electroluminescent devices, and to electronic devices, which comprise these compounds. ##STR00001##

Provided is a perovskite precursor solution, a perovskite thin film, a perovskite cell, and an electrical device. The perovskite precursor solution comprises a perovskite precursor material, a solvent, and an additive; the additive contains, in its structure, a weakly reducing group which has reducibility on a 0 valence corresponding to a monovalent anion in the perovskite-type metal halide in the solution and is inert to a divalent cation in the perovskite-type metal halide; and the additive is a hydrogen halide salt.