High Thermoelectric Performance and Ultrahigh Flexibility Ag₂S_1-Se film on a Nylon Membrane

Flexible thermoelectric (TE) generators have recently attracted increasing attention as they have the potential to power wearable devices using the temperature difference between the human body and the environment. Ag₂S is recently reported to have plasticity near room temperature; however, it has very low electrical conductivity, leading to its poor TE property. Here, to improve the TE property, different amounts of Se (Se/Ag₂S molar ratios being 0.4, 0.5, and 0.6) solid solution-substituted Ag₂S films on a nylon membrane are prepared by combing wet-chemical synthesis, vacuum filtration, and hot-pressing. The film (Se/Ag₂S molar ratio = 0.6) exhibits a better TE performance with a power factor of 477.4 ± 15.20 μW m^-1 K^-2 at room temperature, which is comparable to that of bulk Ag₂S_1-Se. In addition, the film possesses excellent flexibility (only ∼5.4% decrease in electrical conductivity after 2000 times bending along a rod with a radius of 4 mm). The power density of a 6-leg TE generator assembled with the film is 6.6 W/m² under a temperature difference of 28.8 K. This work provides a facile new route to Ag₂S-based TE films with low cost, high TE performance, and ultrahigh flexibility.