Bioinspired 3D BP‐doped Bi ₂ Te ₃ /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 2 Te 3 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 2 Te 3 , boosting the figure of merit (zT) to 0.7 over a temperature range of 300–480 K, that is, 40% higher than pristine Bi 2 Te 3 . 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 D ) of 23.1 , an ultra‐high thermoelectric efficiency for flexible Bi 2 Te 3 ‐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.