Electrosynthesis of a flexible n-type polypyrrole/silver selenide thermoelectric nanocomposite film with ultra-high power factors

n-Type thermoelectric (TE) materials have long been recognized as a fascinating but challenging research topic in TE field mainly due to their scarcity and environmental instability. Moreover, with the advent of flexible wearable TE devices, higher requirements have been put forward for n-type TE materials. In this work, we developed a series of flexible n-type PPy/Ag x Se free-standing nanocomposite films for the first time by a simple and efficient two-step electrosynthesis method, where Ag x Se determines the n-type TE performance of the composite film, and PPy acts both as a flexible substrate and as a conductive bridging agent between the Ag x Se grains. Through the regulation of the deposition potentials for Ag x Se and the deposition time for PPy on the interfacial engineering, the optimized composite film achieved a largest power factor of up to 1831.8 ± 124.6 µW m −1 K −2. This work provides a new, feasible access to the development of high-performance n-type TE materials as well as a broader prospect for TE materials with limited application scenarios in the future.