Greatly Enhanced Thermoelectric Performance of Flexible CuS Composite Film on Nylon by Se Doping.

In this work, flexible CuS films on nylon membranes are prepared by combining a simple hydrothermal synthesis and vacuum filtration followed by hot pressing. The films consist of CuS and CuS two phases with grain sizes from nano to submicron. Doping Se on the S site not only increases the CuS content in the CuS to increase carrier concentration but also modifies electronic structure, thereby greatly improves the electrical properties of the CuS. Specifically, an optimal composite film with a nominal composition of CuSSe exhibits a high power factor of 150.1 μW m K at 300 K, which increases by ~138% compared to that of the pristine CuS film. Meanwhile, the composite film shows outstanding flexibility (97.2% of the original electrical conductivity is maintained after 1500 bending cycles with a bending radius of 4 mm). A four-leg flexible thermoelectric (TE) generator assembled with the optimal film generates a maximum power of 329.6 nW (corresponding power density of 1.70 W m) at a temperature difference of 31.1 K. This work provides a simple route to the preparation of high TE performance CuS-based films.