Design guidelines for chalcogenide-based flexible thermoelectric materials

The power source of rapidly developed flexible and wearable intelligent electronic devices should be stable and have a long working period. Flexible thermoelectric (TE) generators (TEGs) can continuously power electronic devices by harvesting heat from the human body and have become a feasible solution. They are an economical approach to energy collection and have other advantages including chemical stability and noiselessness. Here, we review recently reported chalcogenide-based flexible TE materials and divide them into three categories: flexible substrate supported films, organic-chalcogenide composites, and free-standing flexible films. We discuss recent breakthroughs for chalcogenide-based flexible TE materials with high power factors and/or figures of merit and provide detailed design guidelines for the TE properties and flexibility of the films. We further describe how these films may be assembled into device designs that take advantage of their mechanical flexibility and thermoelectric properties. Besides, the outlook and challenges of wearable inorganic-based thermoelectric materials are proposed.