LAUSR

Abstract In this study, we report advanced density functional theory (DFT) calculations on the structural, electronic, and optical properties of orthorhombic perovskite CH 3 NH 3 PbX 3 ( X = I , Br , Cl ) . We present basic parameters such as lattice constants, electronic structures, effective charge masses, optical absorption spectra, and excitonic binding energies to understand the fundamental properties of CH 3 NH 3 PbX 3 ( X = I , Br , Cl ) . We show that scalar relativistic (SR) DFT calculations yield good band gaps for three systems, and fully relativistic spin-orbital coupling (SOC) DFT calculations give excellent reduced excitonic effective charge masses, as compared to experiments. Moreover, our calculations show that the absorption onset of CH 3 NH 3 PbX 3 moves to short wavelength region with the increase of band gap. Finally, we discussed the relationship between excitonic binding energies and dielectric constants.