Enhanced Thermoelectric Performance of CoSb₃ Thin Films by Ag and Ti Co-Doping

The Skutterudites CoSb₃ material has been the focus of research for the conversion applications of waste heat to electricity due to its ability to accommodate a large variety of ions in the cages that have been proven effective in improving the thermoelectric performance. Although the co-doped CoSb₃ bulk materials have attracted increasing attention and have been widely studied, co-doped CoSb₃ thin films have been rarely reported. In this work, Ag and Ti were co-doped into CoSb₃ thin films via a facile in situ growth method, and the influence of doping content in the thermoelectric properties was investigated. The results show that all the Ag and Ti co-doped CoSb₃ thin films contain a pure well-crystallized CoSb₃ phase. Compared to the un-doped thin film, the co-doped samples show simultaneous increase in the Seebeck coefficient and the electrical conductivity, leading to a distinctly enhanced power factor. The high power factor value can reach ~0.31 mWm^-1K^-2 at 623 K after appropriate co-doping, which is two times the value of the un-doped thin film we have been obtained. All the results show that the co-doping is efficient in optimizing the performance of the CoSb₃ thin films; the key point is to control the doping element content so as to obtain high thermoelectric properties.