Exceptional power factor of flexible Ag/Ag2Se thermoelectric composite films

Herein, we fabricate a high-performance Ag/Ag2Se thermoelectric (TE) film by a novel method. Firstly, Ag/Ag2Se nano-dendritic composite powders were synthesized by a microwave-assisted synthesis method, then the powders were vacuum filtrated on nylon filter membrane followed by hot-pressing. Through optimization of Ag:Se ratios, a maximum power factor of 2436 ± 240 μW m−1 K−2 at room temperature has been acquired. It is one of the best values reported for n-type flexible TE films to date. The high TE performance can be ascribed to the synergy effect between Ag and Ag2Se. Besides, the composite film also shows good flexibility: 94% and 87% of the electrical conductivity are maintained, respectively, when it is subjected to a compressive force and a tensile force after 1000 bending cycles along an 8-mm diameter rod. Meanwhile, the film also shows good stability in air and good moisture resistance. A 6-leg flexible TE generator assembled with the optimized film shows a low internal resistance of ∼ 5 Ω, mainly owing to high electrical conductivity of ∼ 3030 ± 132 S cm−1 of the film. It outputs a voltage and a maximum power of 16.1 mV and 6.08 μW (corresponding power density of ∼ 13.56 W m−2), respectively, at a temperature gradient of 29.6 K. This work provides a great path for the fabrication of exceptional high-performance n-type flexible TE films, which will certainly promote the practical applications of TE films.