Exploring new approaches towards the formability of mixed-ion perovskites by DFT and machine learning

Recent years have witnessed a growing effort in engineering and tuning the properties of hybrid halide perovskites as light absorbers. These have led to the successful enhancement of their stability, a feature that is often counterbalanced by a reduction of their power-conversion efficiency. In order to provide a systematic analysis of the structure-property relationships of this class of compounds we have performed density functional theory calculations exploring fully inorganic ABC₃ chalcogenide (I-V-VI₃), halide (I-II-VII₃) and hybrid perovskites. Special attention has been given to structures featuring three-dimensional BC₆ octahedral networks because of their efficient carrier transport properties. In particular we have carefully analyzed the role of BC₆ octahedral deformations, rotations and tilts in the thermodynamic stability and optical properties of the compounds. By using machine learning algorithms we have estimated the relations between the octahedral deformation and the bandgap, and established a similarity map among all the calculated compounds.