Polypyrrole sheets composed of nanoparticles as a promising room temperature thermo-electric material

Abstract

Polypyrrole (PPy) is a highly conducting polymer with favorable room temperature (RT) thermoelectric (TE) properties. Recently, nanostructure forms of this polymer have been produced with various morphologies by using different surfactants; however, the effect of these morphologies on the TE figure of merit and TE performance has not been well described. In particular, the TE properties of PPy sheets/films composed of nanoparticles (SNPs) have not yet been investigated. In this work, PPy with various morphologies was synthesized using different surfactants. Nanoparticles, nanotubes, continuous sheets and SNPs were produced and characterized by well-known techniques. The structural and TE properties of the as-synthesized nanomaterials were investigated. The obtained results show that SNPs have improved TE properties compared to nanotubes and nanoparticles. The latter two forms have either higher or lower electrical and thermal conductivities than those of SNPs, which suppress their TE performance. The produced SNPs were able to overcome these limitations, as they have high electrical and low thermal conductivities, which result in a high figure of merit and enhanced TE performance. The best SNPs was found to have a power factor, thermal conductivity and figure of merit of 0.17 μV/m⋅K2, 0.132 W/mK2 and 0.4 × 10−3 at room temperature, respectively. These results might be useful for developing future TE materials and devices.