First-principles calculations to investigate electronic, optical, and thermoelectric properties of Na2GeX3 (X = S, Se, Te) for energy applications

Abstract

The optoelectronic, structural, and transport properties of the ternary chalcogenides Na2GeX3 (X = S, Se Te) are investigated by the full-potential linearized augmented plane wave (FP-LAPW) method. Na2GeS3 and Na2GeSe3 have a direct bandgap, while Na2GeTe3 is an indirect bandgap material. The magnitude of the bandgap decreases by replacing S with Se and Te. Optical parameters such as dielectric function, refractive index, reflectivity, absorption coefficient, and energy loss function are also calculated to check their potential in optoelectronic applications. The considered chalcogenide compounds may be promising candidates for photovoltaic devices operating in the UV regions due to their high absorption coefficient in these regions.The calculated thermoelectric parameters (electrical and thermal conductivity, Seebeck coefficient, figure of merit, power factor) indicate that the Na2GeX3 chalcogenides are promising for potential applications in thermoelectric devices.