Electronic and optical properties of lead halide perovskite (MAPbX3) (X = I, Br, and Cl) by first principles calculations

A fundamental understanding of the size of the halide atoms in the perovskite structure is critical to optoelectric device performance. To understand the electronic and optical properties affected by the different electronegativity of the halide anions (with X = I, Br, and Cl) on the lead halide perovskite CH3NH3PbX3 (MAPbX(3)), were explored by density functional theory. Band structures were determined by using GGA and TB09. Optical spectra were simulated based on BSE and RPA. The influence of spin-orbit coupling (SOC) on the systems was also considered. The energy gap (E-g) of MAPbI(3) is lower than that of the other two systems. Using TB09 with SOC provides a good estimate of E-g compared to the experimental values. Using RPA-TB09 provides absorption spectra that are similar to the experimental results. MAPbCl(3) spectra show a strong blue shift than those of the other two. As the atomic size of the halides increases, the lattice parameters and energy gaps increase. Moreover, as the electronegativity of the halides increases, the absorption spectra shift to high energy. The inclusion of SOC provides computational results that are close to the experimental data. We have found that RPA-TB09 provides computational results that are close to the experimental data.