Brief investigations on Cu_xTa_2–xO₅ for thermoelectric and optical responses using density functional and experimental techniques

Cu_xTa_2−xO₅ compositions were investigated for advanced thermoelectric and optical applications, using both simulations and experimental approaches. Density functional theory calculations were performed before the experimental observations to predict the trends of various parameters. Crystal structure analysis confirmed the presence of the orthorhombic Ta₂O₅ phase in all the compositions. The composition and morphology demonstrated impurity-free contents with uniform and crack-free surfaces. Thermoelectric analysis depicted a decrease in Seebeck coefficient from 3.66 μV⋅K⁻¹ to 1.91 μV⋅K⁻¹ and an increase in the value of specific heat from 0.73 J⋅K⁻¹⋅kg⁻¹ to 11.6 J⋅K⁻¹⋅kg⁻¹ upon Cu incorporation in structure. The bandgap was found to reduce from 2.61 to 1.38 eV with Cu-induced electronic states. The real epsilon and static refractive index increased from 3.75 to 4.57 and from 1.93 to 2.11, respectively, with increment in Cu content. The enhanced parameters, focusing on the thermoelectric and optical responses, make these compositions potential candidates for advanced optoelectronic applications.