Ductile Ag 5.98 SSe 0.6 Te 1.4 with High Room‐Temperature Thermoelectric Performance

Abstract Ductile thermoelectric materials and devices, capable of converting human body heat into electricity through the Seebeck effect, are emerging as a promising solution for powering wearable technologies. The recent discovery of Ag 2 S‐based ductile thermoelectric materials has injected new vitality into this field, while the excess carrier concentration of these materials results in substantially lower thermoelectric performance compared to traditional inorganic thermoelectrics. Herein, by reducing the electronegativity of the anion sublattice and producing a silver deficiency at the cation site, an optimal carrier concentration is attained in the Ag 5.98 SSe 0.6 Te 1.4 material, leading to simultaneously high power factor (6.0 µW cm −1 K −2 ) and low total thermal conductivity (0.27 W m −1 K −1 ) at room temperature. Concurrently, it achieves a record thermoelectric figure of merit of 0.65 among Ag 2 S‐based ductile thermoelectrics, while maintaining favorable phase stability and mechanical properties. A six‐leg Ag 5.98 SSe 0.6 Te 1.4 flexible thermoelectric device exhibits a normalized maximum power density of 0.16 W m −1 , an order of magnitude higher than that of existing flexible organic as well as inorganic–organic hybrid thermoelectric devices, demonstrating significant progress in the development of ductile thermoelectrics.