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

•Cu2Se/x%Y2O3 composites were fabricated using solid state recation.•The oxidation states are confirmed by XPS studies.•Composite samples exhibit enhanced micro- hardness.•The lowest resistivity was observed for the sample with x = 0.25 wt%.•The highest power factor was exhibited for the sample with x = 0.75 wt%.