Harnessing Phase‐Transition Hysteresis for Enhanced Thermoelectric Performance of Ductile Ag 2 (S, Se, Te)

ABSTRACT Flexible thermoelectric materials offer a promising route toward self‐powered wearable electronics. The emergence of ductile inorganic semiconductors opens a new paradigm for flexible TE technologies, yet their thermoelectric performance remains far from optimal. Herein, we reveal a pronounced phase‐transition hysteresis in the Ag 2 (S, Se, Te) system, where the transition temperature during cooling is 20–40 K lower than that during heating. Leveraging this hysteresis behavior, we successfully stabilize different structural phases at ambient conditions simply by varying the thermal treatment protocol. Compared to the monoclinic phase obtained by slow cooling from high temperature, the orthorhombic phase obtained by liquid‐nitrogen treatment exhibits worse plastic deformation but much better electrical transport. A maximum power factor of ∼16 µW cm −1 K −2 and a zT of ∼0.5 near room temperature are achieved in the orthorhombic phase, both of which surpass most reported Ag‐based ductile thermoelectric materials. This work provides a new pathway for designing high‐performance ductile thermoelectrics.