Achieving a High Thermoelectric Performance of Tetrahedrites by Adjusting the Electronic Density of States and Enhancing Phonon Scattering

Recently, many researchers have focused on tetrahedrite-based compounds due to their intrinsic low thermal conductivity; however, their thermoelectric performance is limited by the lower power factor. In this case, using Ge doping on Sb sites, the power factor is obviously enhanced due to an increment in carrier concentration and density of states; simultaneously, the thermal conductivity is substantially suppressed by atomic defects. Also, ZnO nanoparticles are introduced in the Ge-doped compounds to further weaken the thermal conductivity. As a result, the maximum dimensionless figure of merit (ZT) of ∼1.0 is obtained for the Cu₁₂Sb_3.96Ge_0.04S₁₃-0.5 wt % ZnO sample at 750 K, which is ∼72% larger than that of Cu₁₂Sb₄S₁₃. All results indicate that suitable elemental doping combined with the incorporation of the nanophase is a very promising approach for Cu₁₂Sb₄S₁₃ tetrahedrites to improve the thermoelectric performance.