LAUSR

Abstract ZnO has a large thermal conductivity that hinders its satisfactory thermoelectric performance. In this work, we add multiple dopants including S, C, Fe and Ni to ZnO simultaneously. A low thermal conductivity ∼3 W m−1 K−1 is obtained, with an initial composition ZnO-1%S-0.15 %C-4%Fe2O3-3%NiO (sample #7), and comparable to the lowest reported values of ZnO-based bulk samples. We attribute the reduction to the Ni induced lattice distortion and the Fe induced microstructural changes. This composition also shows the highest power factor that is ∼60% higher than ZnO due to its highest charge carrier concentration and mobility. The overall dominant carrier scattering is through acoustic phonons rather than impurities. The resultant zT is 2.4 times higher than that of undoped ZnO at 973 K. We find multiple doped ZnO exhibits better thermoelectric performance than any single doped counterpart, providing an effective way to improve the thermoelectric properties of ZnO and other oxides.