Chalcogenide Perovskites for Photovoltaics

Chalcogenide perovskites are proposed for photovoltaic applications. The predicted band gaps of CaTiS₃, BaZrS₃, CaZrSe₃, and CaHfSe₃ with the distorted perovskite structure are within the optimal range for making single-junction solar cells. The predicted optical absorption properties of these materials are superior compared with other high-efficiency solar-cell materials. Possible replacement of the alkaline-earth cations by molecular cations, e.g., (NH₃NH₃)²⁺, as in the organic–inorganic halide perovskites (e.g., CH₃NH₃PbI₃), are also proposed and found to be stable. The chalcogenide perovskites provide promising candidates for addressing the challenging issues regarding halide perovskites such as instability in the presence of moisture and containing the toxic element Pb