Vertically designed high-performance and flexible thermoelectric generator based on optimized PEDOT:PSS/SWCNTs composite films

To solve the long-lasting challenge of low thermoelectric performance of flexible thermoelectric device (F-TEG), in this work, we report a three-dimensional vertically structured F-TEG composed of flexible, stable, and high-performing p- and n-type single-walled carbon nanotube (SWCNT)-based composite films. The p-type SWCNT-based composite film exhibits a high room-temperature power factor of >500 μW m−1 K−2, benefiting from the effective de-doping of the hybridized poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) using a binary co-doping agent composed of NaHCO3 and the polar solvent ethylene glycol (EG). Simultaneously, the n-type SWCNT-based film doped with the amine-rich electron donor polyethyleneimine (PEI) is prepared, exhibiting a high room-temperature power factor of 185.4 μW m−1 K−2 and excellent air stability. By employing flexible supporting foam, vertical p-n thermoelectric legs are realized, and the F-TEG based on these legs exhibits a maximum open-circuit voltage of 23.2 mV and a maximum output power of 2.6 μW at a temperature difference of 48 K, demonstrating a competitive normalized power density of >2.5 μW cm−2 K−2, which advances the low-power flexible wearable field.