Organic Thermoelectric Materials Composed of Conducting Polymers and Metal Nanoparticles

Organic thermoelectric materials consisting of conducting polymers have received much attention recently because of their advantages such as wide availability of carbon, easy syntheses, easy processing, flexible devices, low cost, and low thermal conductivity. Nevertheless, their thermoelectric performance is still not good enough for practical use. To improve their performance, we present herein new kinds of hybrids of organic conducting polymers and metal nanoparticles (NPs). Since hybridization of polyaniline with poly-(N-vinyl-2-pyrrolidone) (PVP)-protected Au NPs decreased the electrical conductivity of polyaniline films from 150 S cm−1 to 50 S cm−1, we carried out direct hybridization of polyaniline with Au NPs without PVP in this study. Direct hybridization improved the electrical conductivity to as high as 330 S cm−1 at 50°C while keeping the Seebeck coefficient at 15 μV m−1 K−2. Poly(3,4-ethylenedioxythiophene) (PEDOT) is another promising conducting polymer. Here, we used hybrid films of PEDOT with Au NPs protected by two kinds of ligands, terthiophenethiol and dodecanethiol (DT), revealing that the hybrid of PEDOT with DT-protected Au NPs showed better thermoelectric performance than pristine PEDOT without Au NPs. Addition of DT-protected Au NPs improved the electrical conductivity of the PEDOT films from 104 S cm−1 to 241 S cm−1 and the thermoelectric figure of merit from 0.62 × 10−2 to 1.63 × 10−2 at 50°C.