Perovskite Chalcogenides with Optimal Bandgap and Desired Optical Absorption for Photovoltaic Devices

Solar cells with organic-inorganic lead halide perovskites have achieved great success and their power conversion efficiency (PCE) has reached to 22.1%. To address the toxicology of lead element and some stability issues associated with the organic-inorganic lead halide perovskites, inorganic lead-free perovskites have gained more attentions from the photovoltaic research community. Herein, a series of chalcogenide perovskites are proposed as optical absorber materials for thin-film solar cells. SrSnSe3 and SrSnS3 are predicted to be direct bandgap semiconductors with the bandgap value being within the optimal range of 0.9-1.6 eV. Both SrSnSe3 and SrSnS3 not only exhibit good optical absorption properties and carrier mobility, but also possess flexible bandgaps that can be continuously tuned within the grange of 0.9-1.6 eV via the element-mixing strategy, thereby render both perovskites as promising candidates for photovoltaic applications.