Mixed formamidinium-methylammonium lead iodide perovskite from first-principles: hydrogen-bonding impact on the electronic properties.

Hybrid perovskites with mixed organic cations such as methylammonium (CHNH, MA) and formamidinium (CH(NH), FA) have attracted interest due to their improved stability and capability to tune their properties varying the composition. Theoretical investigations in the whole compositional range for these mixed perovskites are scarce in part due to the limitations of modeling cationic orientation disorder. In this work, we report on the local variation of the structural and electronic properties in mixed A-site cation MA/FA lead iodide perovskites FAMAPbI evaluated from static first-principles calculations in certain structures where the orientations of organic cations result from examining the energy landscape of some compositions.