Enhanced thermoelectric properties of flexible self-supporting carbon nanotube film/polypyrrole composites

Highlights•CNTF/PPy composites exhibit improved electrical conductivity and power factor•CNTF/PPy composites have good flexibility and mechanical properties•The thermoelectric devices can convert thermal energy from human skin into electricitySummaryFor energy harvesting by flexible thermoelectrics, composite materials have prospects for wearable electronics and require processing methods yielding composites with high thermoelectric performance. Here, we report the fabrication of flexible carbon nanotube film (CNTF)/polypyrrole (PPy) composites by in situ polymerization of PPy on the CNTF. The two-dimensional network structure of CNTF can solve the limitations on the thermoelectric performance of CNT/PPy caused by the poor dispersion and orientation of CNTs. The CNTF/PPy composites exhibit a maximum thermoelectric power factor of 369.2 μWm−1K−2 at 300 K, which is nearly twice of that of the CNTF (191.2 μWm−1K−2). The composites also display flexibility under repeated bending. Composites treated with pre-stretching obtain a higher power factor of 403.8 μWm−1K−2 at 320 K. This method provides a pathway for optimizing the thermoelectric properties of composites based on CNTF. The study is of importance for application prospects in the fields of thermoelectric conversion and multifunctional wearable electronics.Graphical abstract