Flexible thermoelectrics: from silver chalcogenides to full-inorganic devices†
Flexible thermoelectrics is a synergy of flexible electronics and thermoelectric energy conversion. To date, state-of-the-art thermoelectrics is based on inorganic semiconductors that afford high electron mobility but lack in mechanical flexibility. By contrast, organic materials are amply flexible but low in electrical mobility and power output; the inorganic–organic hybrid design is a viable material-level option but has critical device-level issues for practical application. Here, we reported high intrinsic flexibility and state-of-the-art figures of merit (up to 0.44 at 300 K and 0.63 at 450 K) in Ag2S-based inorganic materials, opening a new avenue of flexible thermoelectrics. In the flexible full-inorganic devices made of such Ag2S-based materials, high electrical mobility yielded a normalized maximum power density up to 0.08 W m−1 under a temperature difference of 20 K near room temperature, orders of magnitude higher than organic devices and organic–inorganic hybrid devices. These results promised an emerging paradigm and market of wearable thermoelectrics.