Polythiophene /multi-wall carbon nanotubes (MWNT) composites were prepared by ball-mailing. The morphology
and internal structure of the composites were evaluated by field emission scanning electron microscopy (FESEM), X-ray
diffraction (XRD). Their thermoelectric properties, i.e., the electrical conductivity, the Seebeck coefficient and the
thermal conductivity, were investigated in detail. The remarkably increased electrical conductivity, the slightly increased
Seebeck coefficient and the relatively insensitive thermal conductivity with increasing MWNT content led to an obvious
enhancement in the thermoelectric figure of merit. The results showed that the MWNT were uniformly dispersed in the
polymer matrix, and that increasing the electrical conductivity is the key factor for enhancing the thermoelectric figure of
merit. This study suggested a simple way to improve the thermoelectric performances of conducting polymers.