Ductile Ag _5.98 SSe _0.6 Te _1.4 with High Room‐Temperature Thermoelectric Performance

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 Ag₂S-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_5.98SSe_0.6Te_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 Ag₂S-based ductile thermoelectrics, while maintaining favorable phase stability and mechanical properties. A six-leg Ag_5.98SSe_0.6Te_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.