Revisiting the effects of spin-orbit coupling and dispersion correction on the structural and electronic properties of APbI3 (A=MA, FA) halide perovskite

Predicting the energy band gap for FAPbI₃ and MAPbI₃ halide perovskites using density functional theory (DFT) methods often faces several difficulties and challenges. We investigated the effects of spin-orbit coupling (SOC) and dispersion corrections in DFT calculations on the crystal structure, electronic, and optical properties of MAPbI₃ and FAPbI₃ perovskites. Our findings indicate that incorporating SOC into LDA and GGA-PBE calculations improves the accuracy of energy band gap predictions for FAPbI₃ and MAPbI₃ structures. Furthermore, we demonstrate that adding dispersion corrections to GGA-PBE + SOC calculations indirectly affects structural relaxation, thereby enhancing the accuracy and consistency of MAPbI₃ and FAPbI₃ band gap values, which aligns with experimental data. Our new DFT approach, based on the cost-effective GGA-PBE + SOC + TS/MBD functional, accurately reproduces the electronic properties of MAPbI₃ and FAPbI₃, providing enhanced accuracy and consistency in calculating the energy band gap.