First Principle Study on the Structural Optimization and Electronic Properties of Methylammonium Bismuth Bromide and Methylammonium Galluim Bromide

Abstract

Ab initio calculations for the structural optimization, and Band Structure analyses of CH₃NH₃BiBr₃ and CH₃NH₃GaBr₃ (having 8.33\% dopant replacement percentage each) as possible replacements for the Lead based perovskite CH₃NH₃PbBr₃ were done in this work using Perdew–Burke–Ernzerhof functional of Density Functional Theory as implemented by FHI-aims Code. Molecular visualizations and crystal structures were rendered using JMOL. Optimized lattice constants were calculated for CH₃NH₃BiBr₃ and CH₃NH₃GaBr₃ to be 9.10 A^o and 8.27 A^o respectively, and The Lowest Unoccupied Molecular Orbital (LUMO), Highest Occupied Molecular Orbital (HOMO) and calculated band gap, Band Structure and Density of States (DOS) plots were made to analyse the band structures of these crystals and they were found to be metallic with a band gap of 0.00018636 eV and 0.00022286 eV forCH₃NH₃BiBr₃ and CH₃NH₃GaBr₃ respectively.