First-principles calculation of the optoelectronic properties of doped methylammonium lead halide perovskites: A DFT-based study

Methylammonium lead halide perovskites have emerged as an exciting material for research by virtue of their attractive optoelectronic properties and easy fabrication techniques leading to their use in optical devices, especially solar cells. An extensive knowledge of these properties along with a study of how they can be potentially tuned to suit requirements and improve the efficiency of devices is imperative in the realization of the full potential of these materials. In this regard, we present first-principles modeling and analysis of lead halide organometallic perovskites to determine their optoelectronic properties using density functional theory. Upon validating our model parameters by comparing the calculated optical constants and bandgaps of pure methylammonium lead halide perovskites with published experimental data, we extended the analysis to perovskites doped with various percentages of halogen atoms. We have determined the values of refractive index and extinction coefficient at different doping concentrations for a wide range of photon energies, establishing a comparison between them. In addition, we have investigated the variation in the bandgap and the effective mass of charge carriers with changes in doping concentration. We have also presented the effect of incorporating spin–orbit coupling on the band structure calculations. Our results show a significant reduction in the calculated value of the bandgap and also substantial changes in the values of effective mass upon incorporation of spin–orbit coupling. The data presented in this paper highlight the favorable optoelectronic properties of methylammonium lead halide perovskites and demonstrate the trends in these properties upon halogen doping, thereby facilitating the realization of perovskite-based high-performance solar cells, lasers and other optoelectronic devices with improved efficiency.