The role of hetero-interface structures in enhancing the power factor of Cu2Se/x% Y2O3 composite thermoelectric materials

Abstract

In this study, we have investigated the structural, thermal, electrical, and mechanical properties of the composite system Cu2Se/x% Y2O3 (0 ≤ x ≤ 1.00) as a function of varying Y2O3 concentration, x. The successful incorporation of Y2O3 in the Cu2Se matrix is carried out using the solid-state reaction method, and the same is confirmed by X-ray diffraction analysis. Due to the low concentration of Y2O3, all the prepared composites exhibit monoclinic crystal structure with P2/m space group within the X-ray detection limit at room temperature. The oxidation state of the studied composites is investigated using X-ray photoelectron spectroscopy (XPS). The composites exhibit an increase in mechanical hardness as a function of Y2O3 concentration, whereas the electrical resistivity shows no systematic variation with Y2O3 concentration. The highest resistivity is observed for the sample with x = 1%. The measured Seebeck coefficient (S) value increases with increasing temperature. The positive values of S indicate that the positive charge carriers (holes) dominate the thermoelectric transport. The thermal conductivity of the composites increases as compared to the Cu2Se pristine sample. The overall power factor and ZT of studied composites were found to decrease with the addition of Y2O3 to the Cu2Se system.