Realizing high power factor in p‐type BiSbTe flexible thin films via carrier engineering

Flexible thermoelectric thin films offer a promising avenue for the development of portable and sustainable flexible power supplies. However, a lack of thin films with excellent performance restricts their application in flexible thermoelectric devices. In this study, high‐performance BiSbTe films are successfully prepared using a combination of magnetron sputtering and thermal diffusion. By optimizing carrier concentration to ~ 4.47 × 10 19 cm −3 and simultaneously realizing high carrier mobility of > 120 cm 2 ·V −1 ·s −1 , an impressive room‐temperature power factor of 24.13 μW·cm −1 ·K −2 is achieved in a Bi 0.4 Sb 1.6 Te 3 thin film. The flexible Bi 0.4 Sb 1.6 Te 3 thin film also demonstrates excellent bending resistance and stability (Δ R / R 0 < 5%, Δ S / S 0 < 5%, and Δ S 2 σ / S 0 2 σ 0 < 10%) after 1000 bending cycles at a minimum bending radius of 6 mm. A flexible thin‐film thermoelectric device assembled with p‐type Bi 0.4 Sb 1.6 Te 3 legs achieves a remarkable power output of ~ 82.15 nW and a power density of ~ 547.68 μW·cm −2 under a temperature difference of 20 K.