Sustainable Poly(butylene furanoate)/Carbon Nanotube Composite Fibers for Wearable Thermoelectric Generator

Abstract

Due to the growing interest in renewable energy, thermoelectric materials that are capable of directly converting heat into electricity have attracted significant attention, particularly for wearable thermoelectric generators (WTEGs) that can harvest body heat. Herein, a sustainable composite fiber is developed by combining the bio-based polymer poly(butylene furanoate) (PBF) with single-walled carbon nanotubes (SWCNTs) via wet spinning. Post-annealing of the composite fibers at 150 °C enhances the crystallinity of the PBF and promotes strong π-π interactions with the SWCNTs, thereby resulting in a denser nanotube network along with a three-fold increase in electrical conductivity (113.0 ± 11.6 S cm -1 ) and a maximum power factor of 7.60 ± 0.79 μW m -1 K -2 . The composite fiber also exhibits excellent flexibility, air stability, and thermal durability.For device integration, n-type fibers doped with N-DMBI are woven with the as-fabricated p-type fibers to construct a WTEG.The device with 30 p-n junctions delivers an output voltage and power of 29.4 mV and 15.72 nW, respectively under a temperature gradient of 30 K. When worn on the human wrist and forehead, the WTEG generates voltages of 1.5 and 3.1 mV, respectively. These results highlight the potential of PBF/SWCNT composites for sustainable, flexible thermoelectric energy harvesting in wearable electronics.