Electronic and optical behaviors of methylammonium and formamidinium lead trihalide perovskite materials

Methylammonium (MA) and formamidinium (FA) lead trihalide perovskites, such as MAPbI₃, and FAPbI₃ materials are propitious contenders for solar cells and photovoltaic functionalities because they illustrate band gaps of about 1.5 eV or more. Herein, we scrutinized the electronic structures and optical features of MAPbI₃ and FAPbI₃ halide perovskites using full-potential linearized augmented plane-wave calculations. The structural parameters were acquired using the generalized gradient approximation. The FAPbI₃ halide perovskite was found to display lower stability than the MAPbI₃ material. The total and partial density of states (DOS) were established for these two halide perovskites, in order to reveal the DOS localization for each atomic element by employing the modified Becke–Johnson (TB-mBJ) potential for the exchange–correlation term. The overall optical spectra were also examined over photon energy for these promising systems, involving the dielectric function, absorption coefficient, optical reflectivity, refractive index, and electron energy-loss function. The results of our theoretical investigations are in accordance with the currently published experimental evidence and should be effective in generating novel materials with tremendous functionalities in photovoltaic devices.