Structural descriptors for detecting order–disorder phase transitions in two-dimensional hybrid lead halide perovskites

Correlation analysis of geometric crystal chemical descriptors of the crystal structures of two-dimensional (2D) hybrid lead halide perovskite polymorphs revealed a strong correlation of the order–disorder phase transitions in these compounds with three geometric parameters, namely, the effective volume of the organic cation, the relative distance from the center of mass (RDCM) for the organic spacer cation in the cuboctahedral void of the layer of corner-shared octahedra and the equatorial M–X bond length. The calculated values of the band gaps for the order–disorder phase transitions in the investigated compounds vary up to 0.26 eV. These results will be useful in developing new design principles for tuning the physical properties via structural phase transitions in 2D hybrid lead halide perovskites.