Tellurium/polymers for flexible thermoelectrics: status and challenges

As the heaviest chalcogen atom, tellurium (Te) is endowed with a high Seebeck coefficient and low lattice thermal conductivity, which are the key factors that contribute to a high ZT value in thermoelectricity. The most studied thermoelectric element is Te, and it was theoretically and experimentally studied to be an ideal thermoelectric element. However, the instability and mechanical endurance of Te thermoelectric modules cannot be guaranteed, especially in flexible electronic devices. A focused Te/polymer strategy was recently developed and implemented to address these problems, so combining nanostructured Te with flexible polymers can be an efficient way to construct stable, efficient and flexible thermoelectric generators. In this review, the use of nanostructured Te for thermoelectricity is summarized in brief, and then the preparation methods of Te/polymers are reviewed. Subsequently, the thermoelectric properties and applications of Te/polymers are highlighted, followed by detailed polymer types, including PEDOT:PSS, PANI, P3HT and PPy. Finally, based on current progress and achieved results, the prospects and future directions of Te/polymers are highlighted and discussed.