Enhanced thermoelectric performance of highly conductive poly(3,4-ethylenedioxythiophene)/carbon black nanocomposites for energy harvesting

Abstract The thermoelectric performance of para-methylbenzenesulfonate (p-MeBzs) doped highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) can be improved by the use of carbon black fillers. Thermoelectric nanocomposites were prepared via chemical polymerization. Dodecylbenzenesulfonic acid (DBSA) was introduced before polymerization to act simultaneously as a surfactant for formation of micelles of carbon black and as a doping agent. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the morphology of PEDOT coated carbon black and PEDOT. Electrical conductivity of the composites improved with increase in weight percentage of carbon black from 0% to 30%. Extended chain conformations and increase in electron delocalization reduces the carrier hopping barriers. These contribute to the enhancement of charge carrier mobility. Although electrical conductivity is directly proportional to the increase in the filler content, Seebeck coefficient is more or less constant. Relatively small changes of thermal conductivity can be attributed to the phonon scattering effect in both the carbon black and the thermally insulating PEDOT layers. This study reports that the power factor of the composite was estimated to be 0.993 μW/m K² for 10 wt% filler content and was more than 1.7 times higher than that for pure PEDOT, and the maximum figure of merit (ZT) value was 0.0012 at room temperature.