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 Λ 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 CH₃NH ₃PbX₃ (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 CH₃NH ₃SnX₃ perovskites is slightly improved due to the reduction of the fundamental band gap.