The physical properties of RbAuX (X = S, Se, Te) novel chalcogenides for advanced optoelectronic applications: An ab-initio study

Abstract

The efficient physical properties of alkali-based ternary chalcogenides are investigated in the orthorhombic structure employing the full potential linearized-augmented-plane-wave (FP-LAPW) method within the context of the density functional theory. The used modified Becke-Johnson (mBJ) potential confirms an indirect bandgap nature in the RbAuS and a direct bandgap in the RbAuSe and RbAuTe materials. The computed bulk modulus confirms that RbAuS material is more stable and resistive as compared to RbAuSe and RbAuTe materials. Additionally, linear optical parameters such as the dielectric function, the electron energy loss function, the absorption coefficient, the reflectivity, and the refractive indices have been calculated and discussed extensively. A greater static dielectric constant value is observed for a smaller bandgap value, which verifies Penn’s model. The optical absorption plots indicate that these materials absorb more in the visible region. Some strong sharp peaks in the reflectivity spectra in the ultraviolet region were noticed suggesting them to be promising shielding-type materials against the UV rays. Furthermore, the thermoelectric transport properties are calculated, and the presented results in detail, suggesting that the studied materials are efficient for applications involving thermoelectric devices.