Effective Masses and Electronic and Optical Properties of Nontoxic MASnX3 (X = Cl, Br, and I) Perovskite Structures as Solar Cell Absorber: A Theoretical Study Using HSE06

We calculated the effective masses and electronic and optical properties of CH3NH3SnX3 (X = Cl, Br, I) perovskites as a solar cell absorber using the HSE06 hybrid functional. The computed band gaps are direct at the Gamma point, ranging from 1.67 to 3.0 eV. The effective masses of carriers and the band gaps decrease from chlorine to iodine. Moreover, their hole masses are comparable to those of CH3NH3PbX3 (X = Br and I) phases. The optical dielectric constant does not decrease monotonically when going from X = Cl to Br to I for CH3NH3SnX3 perovskites. Under a small isotropic compressive stress, the photon absorption efficiency of CH3NH3SnX3 perovskites is slightly improved due to the reduction of the fundamental band gap.