Computational study of the physical characteristics of Si-based oxide perovskites for energy generation using DFT

Abstract

SiMO₃ (M = Sn, Ge) silicon-based oxide perovskite compounds are studied using density functional theory (DFT) and Wien2k software to examine their structural, elastic, optical, and electronic properties. The Birch–Murnaghan equation is used to optimize SiSnO₃ and SiGeO₃ compounds and deliver structural stability, whereas the IRelast program is used to find elastic constants to confirm the flexible stability as well as the elastic behavior of the presented compounds. These compounds resist plastic strain and are ductile, scratch resistant, anisotropic, and mechanically stable. The Trans-Blaha modified Becke–Johnson potential approximation calculations demonstrate that the band structure of SiSnO₃ is intermetallic, whereas the second compound, SiGeO₃, is a semiconductor. The evidence obtained from the band structure and density of states of the these compounds demonstrates that SiSnO₃ has an indirect band gap, and the minima of the conduction band are at evenness point X, whereas the maxima of the valence band are at symmetry points M, resulting in an indirect band gap (X–M). Meanwhile, SiGeO₃ has a direct band gap, and the minima of the valence band and maxima of the conduction band occur at symmetry points X. These crystals have low-energy absorption. If we examine the reflectance of ternary molecules SiGeO₃ has a low absorption of up to 2 eV with fluctuations and the absorption increases to a maximum value of 40.0 at 6.50 eV. In contrast, SiSnO₃ exhibits a different increase, and the absorption coefficient decreases to the lowest value of 12.4 eV. Our optical property analysis showed that SiSnO₃ and SiGeO₃ can be used in high-frequency ultraviolet devices. To the best of our knowledge, this is the first DFT-based examination of the characteristics of these crystals.