Enhanced thermoelectric properties of Cu2Se via Sb doping: An experimental and computational study

In this study, Cu 2 Se 1−x Sb x (x = 0.000, 0.005, 0.010, and 0.015) thermoelectric materials were synthesised using a solid-state reaction technique. A first-principles calculation indicated that the formation energy of the substitution of antimony (Sb) on the Se site is negative and more stable than those of copper (Cu) sites. Sb doping enhanced the lamellar orientation, decreased the grain size, and created an acceptor impurity level. The electrical resistivity and Seebeck coefficient decreased with increasing Sb doping. A minimum reduction in the thermal conductivity by approximately three times that of the undoped sample was obtained at x = 0.005 with a value of 0.40 W/m K at 523 K. The maximum figure of merit ( ZT ) was obtained at x = 0.005 with a value of 0.47 at 523 K. These findings indicate that substituting Sb into Se sites is an efficient approach for improving copper selenide (Cu 2 Se) thermoelectric materials. • Optimisation of the α -Cu 2 Se structure using a first-principal study based on DFT. • The effect of Sb doping on thermoelectric properties of α-Cu 2 Se were studied. • The substitution of Sb on the Se site contributed to a decrease in the energy gap. • Electrical resistivity and thermal conductivity decreased with increasing Sb doped. • ZT was increased by 3 times, from 0.15 for Cu 2 Se to 0.45 for Cu 2 Se 0.95 Sb 0.005 .