Thermoelectric properties of regioregular poly(3-hexylthiophene) (P3HT) were investigated in correlation with doping level measured by a potential-step chronocoulometry (PSC) method. It was found that the log-log plot of Seebeck coefficients against doping levels showed a good linearity, whose slope value was around -1.

To establish the correlation between the thermoelectric properties of conducting polymers and their doping levels, we have utilized the potential-step chronocoulometry for the quantitative estimation of the doping levels. In this paper, three types of poly(3-hexylthiophene)s synthesized by different polymerization methods were investigated. The electrical conductivities and the Seebeck coefficients of poly(3-hexylthiophene)s with various doping levels were measured and plotted against the doping level. It was found that the electrical conductivity linearly increased with increasing the doping level in the range of 1-10%, and then saturated. On the other hand, the relationship between the Seebeck coefficient and the doping level showed a good linearity in all the polymers.