Encapsulated Ag2Se-based flexible thermoelectric generator with remarkable performance

Flexible thermoelectric generators hold great potential for powering wearable electronics. Herein, we employ a novel encapsulation technology to fabricate a Ag2Se-based composite film, which possesses a remarkable room-temperature power factor (PF) of 25.6 μW cm−1 K−2 and a peak PF of ∼27 μW cm−1 K−2 at 380 K. The microscopic origin of the above performance is attributed to the appearance of CuAgSe second phase by our in-situ transmission electron microscopy evidences. Moreover, the encapsulation guarantees the Ag2Se layer in a zero-strain state, contributing to a negligible relative resistance change (<0.2%) even after 2000 bending cycles under a bending radius of 3 mm. The encapsulated flexible thermoelectric generator assembled with six Ag2Se legs demonstrates a maximum power density of 130 W m−2 at a temperature difference of 60 K and is compatible with harsh working environment.