Solvent-optimized monolithic SWCNT-based thermoelectric generator for efficient electricity harvesting from body heat and sunlight

Abstract

A lightweight and flexible thermoelectric generator (TEG) based on monolithic designed single-walled carbon nanotubes (SWCNT) is successfully developed, which can effectively harvest electricity from hybrid sources of body heat and solar light with high energy output. By properly selecting SWCNT dispersion solvents, SWCNT films with an optimal p-type power factor of 526 μW m−1 K−2, and n-type power factor of 489 μW m−1 K−2 are achieved, among the highest reported power factors for solution-processed CNT-based films. Monolithic TEG based on the optimized SWCNT films leads to exceptionally high device performance both under constant heat and sunlight. The 8-leg TEG exhibits output power density over 110.2 μW cm−2 and 25.3 μW g−1 with a temperature gradient of 28 K, which is among the best energy-harvesting performance of CNT-based TEG. In addition, a large temperature gradient over 22.1 K is generated under AM1.5 1 sun illumination, owing to the SWCNT films act not only as TE modules but also solar-light absorber, and the TEG yields a record-high output power density of 66.0 μW cm−2 and 15.1 μW g−1 under 1 sun. Our TEG design based on SWCNT shows great potential in powering flexible micro-watt electronics by effectively harvesting electricity from both body heat and sunlight.