Wet-spun PEDOT:PSS/CNT composite fibers for wearable thermoelectric energy harvesting

Fiber-based thermoelectric materials have received increased attention as they are light weight and can be sewn and woven for portable and wearable thermoelectric generators. In this work, Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/single-walled carbon nanotube (SWCNT) composite fibers were fabricated by a continuous wet spinning process using concentrated sulfuric acid as a coagulation bath, which could effectively remove the excess PSS and result in improved electric conductivity. With a SWCNT content of 50 wt%, the PEDOT:PSS/SWCNT composite fibers show a high electric conductivity of 2982 S cm−1 and a Seebeck coefficient of 27.1 μV K−1, leading to a promising power factor of 219 μW m−1 K−2. By further treated with sodium hydroxide aqueous solution, the PEDOT:PSS/SWCNT fibers exhibit an enhanced Seebeck coefficient of 36.4 μV K−1 and a power factor of 280 μW m−1 K−2, which is higher than most PEDOT:PSS-based thermoelectric fibers. The mechanism of the enhancement of thermoelectric properties for the composite fibers was discussed. A flexible thermoelectric generator with five pairs of PEDOT:PSS/SWCNT fibers and copper wires were assembled and the electrical power generation capability were evaluated, demonstrating its potential application in wearable electronic devices.