Improved thermoelectric performance in n-type flexible Bi2Se3+x/PVDF composite films

Bismuth selenide materials (Bi2Se3) have high performance around room temperature, demonstrating potential in thermoelectric applications. Presently, most vacuum preparation techniques used to fabricate the film materials, such as magnetron sputtering and molecular beam epitaxy, usually require complex and expensive equipment. This limits the practical applications of flexible thermoelectric films. Here, we prepared Bi2Se3+x nanoplate/polyvinylidene fluoride composite films with good flexibility using a facile chemical reaction method. Their thermoelectric performance and microstructures were systematically studied. The composite films exhibit a highly preferred orientation along (015). The carrier concentration and mobility were optimized by adding excessive element Se, eventually leading to an improvement in thermoelectric performance. The optimized power factor is 5.2 μW/K2m at 300 K. Furthermore, the performance remains stable after 2500 bending cycles at a radius of 1 cm, suggesting promising applications in wearable/portable electronics