Recent advances in oxide thermoelectric materials and modules

Due to the growing concern on depletion of non-renewable resources, waste heat harvesting has become one of the effective approaches for solving the energy shortage issue. Oxide thermoelectric materials have the advantages of low cost, environment-friendly manufacturing and chemical stability at high temperatures. However, compared to traditional thermoelectric materials, they exhibit only modest thermoelectric properties due to their low electrical- and high thermal conductivity. Numerous studies have been done to improve their thermoelectric response by doping. These oxide materials mainly include the p-type Ca3Co4O9 and n-type ZnO, SrTiO3, and CaMnO3. By connecting these both types of thermoelectric oxides in series, a module which is capable of generating considerable power can be obtained. In this review, we present the progress made on p-type and n-type thermoelectric oxides in recent years. We discuss the electronic structure of these oxides as it plays an important role in determining the thermoelectric properties. We also discuss the advanced modules which have been fabricated using these thermoelectric oxide couples.