Free‐Standing Single‐Walled Carbon Nanotube/SnSe Nanosheet/Poly(3,4‐Ethylenedioxythiophene):Poly(4‐Styrenesulfonate) Nanocomposite Films for Flexible Thermoelectric Power Generators

Flexible single‐walled carbon nanotube (SWCNT)/SnSe nanosheet (NS)/poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) nanocomposite films are first successfully prepared by a facile vacuum filtration method on nylon membrane. An optimized power factor of 109.9 μWm −1 K −2 for the as‐prepared free‐standing nanocomposite film with 60 wt% SWCNTs is obtained at the temperature of 380 K, and the electrical conductivity only decreases by 1% after 1000 bending cycles (the bending radius is ≈4.3 mm), indicating excellent flexibility. A flexible thermoelectric generator consisting of 8‐unit free‐standing composite film strips (25 mm × 4 mm for each strip) is assembled on a polyimide substrate, which can generate an open‐circuit voltage of 20.6 mV and a maximum output power of 1.16 μW at a temperature gradient of 74.4 K. This work offers quite an effective strategy for preparation of high‐performance flexible free‐standing thermoelectric composite films, and the as‐prepared films can avoid excess heat loss induced by the substrate‐adherent layer of thin films, when compared with the traditional thermoelectric composite films prepared on different kinds of substrates, e.g., glass substrate. Therefore, the composite films have a great potential to be used for the flexible thermoelectric devices.