High-performance flexible wavy-structure thermoelectric generator based on (Bi, Sb)₂Te₃ films for energy harvesting

The development and advancement of thin-film thermoelectric generator (TEG) have significant implications in wearable electronics. However, the simultaneous achievement of higher power density, miniaturization, and flexibility in TEG has remained a significant challenge, impeding their widespread commercial application. Herein, high-performance inorganic thermoelectric films (Bi2Te3 and Bi0.5Sb1.5Te3) are employed compatibly deposited at polyimide (PI) substrate as the p/n legs to design and demonstrate a three-dimensional (3D) wavy-structure thin-film TEG. This 3D structure design enables vertical heat flow in the planar thin-film TEG, and effectively harnesses out-of-plane temperature differences. The integrated wavy-structure TEG without an additional heat sink, gives the highest open voltage of 54.6 mV under a vertical temperature gradient of 11 K, corresponding to a high normalized output power density of similar to 10.6 mu W cm(-2) K-2, surpassing previously reported flexible thin film TEG by over 5 times. Moreover, the TEG exhibits excellent flexibility and stretchability which is beneficial for application on curved heat sources. The design strategy conceived in this work will promote the development of high-performance TEG for flexible and wearable applications.