High-Performance Polyaniline-Coated Carbon Nanotube Yarns for Wearable Thermoelectric Generators

Carbon nanotubes/polyaniline (CNTs/PANI) composites have attracted significant attention in thermoelectric (TE) conversion due to their excellent stability and easy synthesis. However, their TE performance is far from practical demands, and few flexible yarns/fibers have been developed for wearable electronics. Herein, we developed flexible CNTs/PANI yarns with outstanding TE properties via facile soaking of CNT yarns in a PANI solution, in which the PANI layer was coated on the CNT surface and served as a bridge to interconnect adjacent CNT filaments. With optimizing PANI concentration, immersing duration, and doping level of PANI, the power factor reached 1294 μW m^-1 K^-2 with a high electrical conductivity of 3651 S cm^-1, which is superior to that of most of the reported CNTs/PANI composites and organic yarns. Combining outstanding TE performance with excellent bending stability, a highly integrated and flexible TE generator was assembled consisting of 40 pairs of interval p-n segments, which generate a high power of 377 nW at a temperature gradient of 10 K along the out-of-plane direction. These results indicate the promising application of CNTs/PANI yarns in wearable energy harvesting.