First-principles calculations of orthorhombic chalcogenide ABX3 (A = Ca, Sr, Ba; B = Ge, Sn; X = O, S, Se, Te) perovskites by cation and anion variation

The first-principles calculations are used to investigate on the structural, electronic, optical properties of orthorhombic chalcogenide ABX(3) (A = Ca, Sr, Ba; B = Ge, Sn; X = O, S, Se, Te) perovskites. All cation and anion variations will only change the lattice parameters, but the orthorhombic crystal structures maintain stability apart from CaGeS3. The electron density difference demonstrates the differences in interaction strength and degree of electron localization to some extent in various systems. The sulfide perovskites are all semiconductors with bandgaps between 1 and 3 eV while the variable anions can realize the transition from the insulator (5.263 eV) to narrow semiconductors (0.134 eV). Besides, the photoresponse can be modulated to a better match with solar irradiance by anion variation. Among all studied SrSnX3 (X = O, S, Se and Te) materials, SrSnSe3 has the best performance as a solar absorber due to its best light absorption and proper bandgap value (similar to 1.6 eV).