Influence of the Chemical Composition on the Perovskites Anharmonicity: Toward a Stable Inorganic Perovskite

Usual metal halide perovskites suffer from various instability sources, including the presence of a rich sequence of phase transitions, due to the presence of various soft phonon modes at the atomic scale. The systematic investigation of inorganic ABB’(XX’) halide perovskites with ab initio methods, coupled with the analysis of their structural, electronic, and dynamic parameters, revealed the existence of a few compositions that did not posess such phonon modes; which could lead to metastable cubic phase perovskites. Moreover, a correlation between the amplitude of the various distortions in the metastable distorted phases and the phenomenomenological Goldschmidt tolerance factor () could be established, showing that through the alloying using similar ions and the restriction of in a narrow zone, distortions can be minimized. Combined with the analysis of thermodynamics and the bandgap, it leads to the elaboration of criteria for the optimization of performant and more stable perovskites for photovoltaic applications.