Investigation of a potential photovoltaic absorber based on first principles spectroscopic screening of chalcogenide perovskites: CaZrX₃ (X = S, Se)

Metal chalcogenide perovskites have a number of benefits over lead-halide perovskites, including superior moisture resistance, light-induced degradation together with nontoxic elemental composition, higher absorption, and exceptional carrier transport properties. These materials have orthorhombic phase Pnma and are potential candidate materials to be used as absorber materials in solar cells. In this study, we propose metal chalcogenide perovskites CaZrX₃ (X = S, Se) as a candidate absorber material. Therefore, the investigation of the structural, electrical, optical, thermal, and thermoelectric properties of CaZrX₃, where X = S, Se, is being carried out using first principles methods. These proposed semiconducting compounds will meet the requirement for stability against volume change. These materials show a direct band gap of 1.812 eV and 1.117 eV at the Γ point. To better understand the optical transitions in the material, the real and imaginary parts of the dielectric function have been calculated. The remarkable absorption coefficient \((\alpha )\) $(\alpha )$ exceeding 10⁵ cm⁻¹ above photon energy exceeding bandgap indicates that the materials are suitable for the visible light absorption. For the estimation of photovoltaic performance of CaZrX₃ (X = S, Se) and to demonstrate the high photo-absorptivity, the spectroscopic-limited maximum efficiency has been calculated. The results show a maximum photovoltaic efficiency of 26.4% and 32.4% for CaZrS₃ and CaZrSe₃ respectively at the thickness L = 100 nm. We have also calculated the thermoelectric coefficients. These perovskites are gaining more attention as a thermoelectric material because of their higher Seebeck coefficient, and ultra-low thermal conductivity.