Bioinspired 3D BP-doped Bi₂Te₃/hydrogel hybrid films : ultra-efficient flexible TEGs for wearable energy harvesting

Abstract

Flexible thermoelectric materials capable of efficiently converting low-grade body heat into electricity are crucial for self-powered wearable electronics, yet remain elusive due to the competing requirements of high energy conversion efficiency, mechanical resilience, and environmental adaptability. Here, we present a synergistic integration of black phosphorus (BP)-doped Bi<inf>2</inf>Te<inf>3</inf> with a biomimetic 3D hydrogel, resulting in a hybrid film that simultaneously achieves high thermoelectric performance and enhanced flexibility. Black phosphorus (BP) doping induces dual carrier-phonon engineering in Bi<inf>2</inf>Te<inf>3</inf>, boosting the figure of merit (zT) to 0.7 over a temperature range of 300–480 K, that is, 40% higher than pristine Bi<inf>2</inf>Te<inf>3</inf>. At the same time, the hydrogel's bioinspired architecture provides exceptional mechanical durability, conformal skin contact, and thermal insulation to sustain operational temperature gradients. The resulting wearable thermoelectric generator delivers an open-circuit voltage (OCV) of 275 mV and a power density (P<inf>D</inf>) of 23.1 (Formula presented.), an ultra-high thermoelectric efficiency for flexible Bi<inf>2</inf>Te<inf>3</inf>-based devices. This work establishes a scalable, eco-friendly platform for wearable thermoelectrics, demonstrating extensibility to narrow-gap materials where synergistic dopant engineering and nanostructuring improve the efficiency to power the next generation of autonomous health monitors and the Internet of Things ecosystems.