Flexible N-Type Thermoelectric Composites Based on Non-Conductive Polymer with Innovative Bi(2)Se(3)-CNT Hybrid Nanostructured Filler

This research is devoted to the fabrication of polyvinyl alcohol (PVOH) based n-type thermoelectric composites with innovative hybrid bismuth selenide-multiwalled carbon nanotube (Bi(2)Se(3)-MWCNT) fillers for application in flexible thermoelectric devices. Hybrid fillers were synthesized by direct deposition of Bi(2)Se(3) on multiwalled carbon nanotubes using a physical vapor deposition method, thus ensuring direct electrical contact between the carbon nanotubes and Bi(2)Se(3). The Seebeck coefficient of prepared PVOH/Bi(2)Se(3)-MWCNT composites was found to be comparable with that for the Bi(2)Se(3) thin films, reaching −100 µV·K(−1) for the composite with 30 wt.% filler, and fluctuations of the resistance of these composites did not exceed 1% during 100 repetitive bending cycles down to 10 mm radius, indicating the good mechanical durability of these composites and proving their high potential for application in flexible thermoelectrics. In addition, other properties of the fabricated composites that are important for the use of polymer-based materials such as thermal stability, storage modulus and linear coefficient of thermal expansion were found to be improved in comparison with the neat PVOH.