Thermoelectric properties and conduction mechanism of conductive polythiophenes

In this study, we synthesised conductive polymers of polythiophene series and evaluated their thermoelectric properties in the temperature range from 88 K to 350 K. Poly-hexylthiophenes showed a conduction mechanism of the nearest-neighbour distance hopping (NDH) in the measured temperature range, while the main conduction mechanism of polythiophenes was the variable range hopping (VRH). Only polythiophenes with low electrical conductivity (such as 0.02 S/cm) presented NDH at temperatures of below 200 K. The conduction mechanism is changed by the distance between the thiophene main chains and the kinetic energy of carriers.