Enhanced thermoelectric performance by self-assembled layered morphology of polypyrrole nanowire/single-walled carbon nanotube composites

Organic conducting polymer thermoelectric (TE) composites have witnessed a rapid progress in the recent several years. Here, we report a new morphology design strategy to enhance the TE performance by a unique layered morphology containing nanosheets of single-walled carbon nanotubes (SWCNTs) sandwiched by polypyrrole (PPy) nanowires. The free-standing PPy/SWCNT composite films were fabricated via convenient physical mixing followed by vacuum filtration, where PPy nanowires were synthesized by chemical oxidative polymerization. A typical layered morphology, composed of parallel SWCNT nanosheets sandwiched by PPy nanowires with a diameter of 55-75 nm, was directly observed by scanning electron microscopic images. The composites reveal greatly enhanced TE performance with the maximum power factor of 21.7 +/- 0.8 mu W m(-1) K-2, which is the largest value among PPy and its composites reported so far. Furthermore, both SWCNT content and surfactant type have obvious effects on the TE performance. The present study opens a new avenue to greatly enhance the TE performance by construction of layered morphology containing inorganic nanosheets sandwiched by polymer nanostructures. (C) 2016 Elsevier Ltd. All rights reserved.