Comprehensive analysis of the structural, electronic, elastic and optical properties of ternary chalcogenides pnictogens InPnCh3 (Pn = Bi, Sb; Ch = S, Se) compounds: First-Principles calculations

Abstract

This study employs density functional theory to investigate the structural, electronic, elastic, and optical properties of InPnCh₃ chalcogenides (Pn = Sb, Bi; Ch = S, Se). These materials consist of elements that are abundant on Earth, non-toxic, and hold promise for applications in optoelectronics and energy conversion. All calculations are performed following optimization of calculation parameters and geometry using the Pnma (62) space group. Additionally, this study predicts the properties of InBiSe₃, which has not yet been synthesized. Band structure and density of states (DOS) analyses reveal that these materials exhibit indirect band gaps. Among them, InSbSe₃ exhibits the smallest band gap energy of 1.66 eV, while InBiS₃ demonstrates the largest at 2.45 eV (HSE06). The anisotropic nature of these materials is reflected in their directional-dependent properties, with the highest elastic moduli values along the y-axis (Young's modulus E = 87 GPa for InBiS₃). Furthermore, the optical properties of these chalcogenides, including absorption α(ω), dielectric function $\epsilon \left(\omega \right)={\epsilon }_1\left(\omega \right)+{\epsilon }_2\left(\omega \right)$, refractive index $n\left(\omega \right)$, and loss function $L\left(\omega \right)$, are investigated. The results indicate that these materials are efficient absorbers of visible radiation, with an absorption coefficient $\alpha \left(\omega \right)$ ≈ 95000 cm⁻¹ at 2.75 eV (450 nm) for InBiSe₃.