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Thermoelectric energy conversion is effective and important in harvesting electricity from waste heat sources with low temperature gradients relative to the environmental temperature. These temperature gradient too small to measure harvest energy by using conventional methods, but thermoelectric systems have the ability to convert any temperature gradient into electricity. Significant improvements to the thermoelectric figure of merit ZT have achieved in recent years, primarily due to the engineering of material composition and nanostructure in inorganic semiconductors. However, many present high-ZT materials are based on low-abundance elements that pose challenges for scale-up, as they entail high material costs in addition to brittleness and difficulty in large-area deposition. Here we demonstrate a strategy to improve ZT in conductive polymer nanocomposites. Our composites, containing single-wall carbon nanotubes, poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) show large thermo power with large electrical conductivities, resulting in large thermoelectric power factors. By changing volume fraction of composites and post treatment of DMSO solvent, we show that all three parameters constituting ZT vary in a manner so that ZT increases. Increasing volume fraction up to 75% and post treatment with DMSO, we achieve ZT ~ 0.7 at room temperature. |