Structural, Elastic and Optoelectronic Properties of Inorganic Cubic Frbx3 (B = Ge, Sn; X = Cl, Br, I) Perovskite : The Density Functional Theory Approach

Inorganic metal-halide cubic perovskite semiconductors have become more popular in industrial applications of solar cells and optoelectronic devices. Among various perovskites, lead-free materials are currently most explored due to their non-toxic effect on the environment. In this study, the structural, electronic, optical, and mechanical properties of lead-free cubic perovskite materials FrBX 3 (B=Ge, Sn; X= Cl, Br, I) are investigated through the first-principles density-functional theory (DFT) calculations. These materials are found to exhibit semiconducting behavior with direct bandgap energy and mechanical phase stability. The observed variation in the bandgap is explained based on the substitutions of cations and anions sitting over B and X-sites of the FrBX 3 compounds. The high absorption coefficient, a low reflectivity, and a high optical conductivity, make these materials suitable for the solar cells and other optoelectronic device applications. It is observed that the material containing Ge (germanium) in B-site has higher optical absorption and conductivity than Sn containing materials. A systematic analysis of the electronic, optical, and mechanical properties suggests that among all the perovskite material, FrGeI 3 would be the potential candidate for solar cell applications