Exceptionally High Power Factor Ag_2Se/Se/Polypyrrole Composite Films for Flexible Thermoelectric Generators

摘要

A facile method to prepare flexible n-type Ag2Se/Se/polypyrrole (PPy) composite films is developed. First, Ag2Se nanostructures (NSs) are wet chemically synthesized; PPy is then in situ polymerized at the surface of the Ag2Se NSs; and finally, the Ag2Se/Se/PPy composite film on a porous nylon membrane is fabricated by a vacuum-assisted filtration process followed by hot pressing. An optimal composite film shows an exceptionally high power factor of approximate to 2240 mu W m(-1) K-2 at 300 K, mainly because of the synergistic effect between well-developed crystalline Ag2Se grains and a small amount of Se and PPy. The film also possesses outstanding flexibility (only about 6.5 decrease in electrical conductivity after 1000 times bending along a rod with a radius of 4 mm). Moreover, a flexible thermoelectric generator composed of six legs of the film outputs a voltage of 21.2 mV and a maximum power of 4.04 mu W (corresponding power density of 37.6 W m(-2)) at a temperature difference of 34.1 K, verifying exceptionally high thermoelectric properties. This work shows the promise of the as-prepared composite film for practical applications in wearable devices and will surely promote the research and development of flexible TE generators.