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 × 10¹⁹ cm⁻³ and simultaneously realizing high carrier mobility of > 120 cm²·V⁻¹·s⁻¹, an impressive room-temperature power factor of 24.13 μW·cm⁻¹·K⁻² is achieved in a Bi_0.4Sb_1.6Te₃ thin film. The flexible Bi_0.4Sb_1.6Te₃ thin film also demonstrates excellent bending resistance and stability (ΔR/R₀ < 5%, ΔS/S₀ < 5%, and ΔS²σ/S₀²σ₀ < 10%) after 1000 bending cycles at a minimum bending radius of 6 mm. A flexible thin-film thermoelectric device assembled with p-type Bi_0.4Sb_1.6Te₃ 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.