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 mu Wm(-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 approximate to 4.3 mm), indicating excellent flexibility. A flexible thermoelectric generator consisting of 8-unit free-standing composite film strips (25 mm x 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 mu W 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.