Flexible Thermoelectric Generators Based on Single-Walled Carbon Nanotube/Poly(aniline-co-acrylonitrile) Composites

Composites of polyaniline (PANI) with carbon nanotubes (CNTs) are widely studied for thermoelectric applications. In this work, acrylonitrile (AN) is incorporated into the backbone of aniline (ANI) to form a poly(ANI-co-AN) copolymer, which is in situ wrapped around the single-walled carbon nanotubes (SWNTs) to enhance the thermoelectric performance. The idea is to address the well-known inverse relationship between the Seebeck coefficient and electrical conductivity through the carrier concentration, by using the insulating nature of AN to better control the charge transport properties. The results show that the carrier concentration is reduced without deteriorating the carrier mobility in the 70% SWNT/30% poly(90ANI-co-10AN) composites as compared to pristine SWNT/PANI. Consequently, the highest power factor (PF) reached in this work is 201 µWm⁻¹K⁻² for the 70% SWNT/30% poly(90ANI-co-10AN) composite, representing a ≈1.7-fold improvement over SWNT/PANI composites prepared under identical conditions. Further, a flexible thermoelectric generator is fabricated using SWNT/poly(ANI-co-AN) composite films, demonstrating a promising output power and power density of 117 nW and 43.3 µWcm⁻², respectively, at a temperature difference of 30 K. These findings suggest that wrapping CNTs with copolymers comprising monomers of both conducting and insulating polymers can be a promising strategy to enhance the thermoelectric properties.