Electric conductivity changes of polypyrrole and polythiophene films with heat-treatment Original Research Article

The electric conductivities of polypyrrole and polythiophene films have been measured as a function of heat-treatment temperature. From room temperature to 150°C, the conductivity of polypyrrole film remained constant. From 150 to 300°C, the conductivity dropped due to the decomposition of polypyrrole and the loss of dopant ion (ClO4−). Above 300°C, the conductivity increased again. Above 750°C, the conductivity was higher than that of the original film due to the formation of carbonaceous materials. The polythiophene film showed a similar tendency to the polypyrrole film. Chemical and spectroscopic methods such as elemental analysis, FT-IR and ESR were employed to determine the origin of the electric conductivity changes.