Electrical conductivity and thermoelectric power of polybithiophenepolystyrene composites

Conducting composites consisting of polybithiophene and based on porous crosslinked polystyrene as host polymer were synthesized in the vicinity and above the percolation threshold by oxidative polymerization. (i) Measurements of electrical properties versus the temperature for different degrees of doping with Cu(ClO4)2 were carried out. In the temperature range 90–300 K, d.c. electrical conductivity is weakly activated. The dominantly contributing mechanism is interpreted on the basis of a hopping model involving bipolaronic clusters. Otherwise, the thermoelectric power has metallic magnitude with positive sign and increases as temperature increases. (ii) The electrical conductivity variations of polythiophene-polystyrene composites doped with FeCl3 versus the concentration in the dopant were carried out at room temperature below and above the percolation threshold. Results are analysed on the basis of the percolation theory and the random resistor network (RRN) model.