High Power Factor Ag/Ag₂Se Composite Films for Flexible Thermoelectric Generators

Herein, we fabricated an Ag/Ag₂Se composite film on a flexible nylon membrane with a high power factor and excellent flexibility. First, Ag nanoparticles and multiscale Ag₂Se nanostructure composite powders were prepared by wet chemical synthesis using Se nanowires, silver nitrate, and l-ascorbic acid as raw materials, followed by vacuum-assisted filtration of the composite powders on a porous nylon membrane and then hot pressing. The optimized composite film shows a very high power factor of 1860.6 μW m⁻¹ K⁻² (with a corresponding electrical conductivity of 3958 S cm⁻¹) at room temperature. The composite film retains 93.3% of the original electrical conductivity after 1000 bending cycles around a rod with a diameter of 8 mm. At a temperature difference of 27 K, an 8-leg thermoelectric prototype device assembled with the optimized composite film generates a maximum power of 7.14 μW with a corresponding power density of 8.74 W m⁻². This work provides a new strategy to synthesize flexible thermoelectric films with both a high power factor and high electrical conductivity.