Ultrahigh thermoelectric properties of <i>p</i>‐type Bi<sub><i>x</i></sub>Sb<sub>2−<i>x</i></sub>Te<sub>3</sub> thin films with exceptional flexibility for wearable energy harvesting
Zhuanghao Zheng, Yiming Zhong, Yi‐Liu Li, Mohammad Nisar, Adil Mansoor, Fu Li, Shuo Chen, Guangxing Liang, Ping Fan, Dongyan Xu, Meng Wei, Yuexing Chen
Abstract
Abstract Use of a flexible thermoelectric source is a feasible approach to realizing self‐powered wearable electronics and the Internet of Things. Inorganic thin films are promising candidates for fabricating flexible power supply, but obtaining high‐thermoelectric‐performance thin films remains a big challenge. In the present work, a p ‐type Bi x Sb 2− x Te 3 thin film is designed with a high figure of merit of 1.11 at 393 K and exceptional flexibility (less than 5% increase in resistance after 1000 cycles of bending at a radius of ∼5 mm). The favorable comprehensive performance of the Bi x Sb 2− x Te 3 flexible thin film is due to its excellent crystallinity, optimized carrier concentration, and low elastic modulus, which have been verified by experiments and theoretical calculations. Further, a flexible device is fabricated using the prepared p ‐type Bi x Sb 2− x Te 3 and n ‐type Ag 2 Se thin films. Consequently, an outstanding power density of ∼1028 μW cm −2 is achieved at a temperature difference of 25 K. This work extends a novel concept to the fabrication of high‐performance flexible thin films and devices for wearable energy harvesting.