Preparation and thermoelectric properties of polythiophene/multiwalled carbon nanotube composites

•The composites prepared by solution mixing showed the best thermoelectric properties.•The Seebeck coefficient slightly fluctuates with increasing MWNT content.•The electrical conductivity increases remarkably with increasing MWNT content.•The highest ZT of 8.71 × 10−4 was obtained with 80 wt.% MWNT.

Different polythiophene (PTh)/multiwall carbon nanotube (MWNT) composites with 30 wt.% and 50 wt.% MWNT were prepared by mechanical ball milling, solution mixing and in situ composite, respectively. The composites prepared by solution mixing showed the best thermoelectric properties among these methods. Therefore, the morphology, internal structure and thermal stability of the composites by solution mixing were evaluated by SEM, XRD, FTIR and TGA. The results showed that the MWNT were uniformly dispersed in the polymer matrix and the composite materials exhibited good thermal stability under 200 °C. The effect of MWNT content in the composites on thermoelectric properties, such as electrical conductivity, Seebeck coefficient and thermal conductivity were investigated. With increasing MWNT content, the Seebeck coefficient slightly fluctuates, varying from 27.7 to 22.7 μV/K, and the thermal conductivity slightly increases, but the electrical conductivity increases remarkably, and thus leads to enhance the figure of merit (ZT) obviously. The highest ZT of 8.71 × 10−4 at 120 °C was found in the composite with 80 wt.% MWNT.

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