Electronic and gap properties of lead-free perfect and mixed hybrid halide perovskites: An ab-initio study

Abstract

Hybrid halide perovskites are currently under intense investigation due to their potential applications in optoelectronics and solar cells. Among them, MAPbI3 where MA stands for the methylammonium cation, exhibits ideal properties for solar cells. In attempt to identify new lead-free halide perovskites we have studied using ab-initio electronic structure calculations in conjunction with hybrid functionals a series of MABX3 compounds where B is a divalent cation and X is a halogen atom. Our results suggest that the compounds under study exhibit a variety of lattice constants and energy band gaps. Especially, MAGeCl3 and MAGeBr3 are susceptible to replace MAPbI3 in devices since they show comparable energy gaps. Further calculations on the mixed hybrid halide perovskites show that we can tune the values of the energy gap although no simplified pattern exists. Our results pave the way for further investigation on the use of these materials in technology relevant applications.