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

The electric conductivities of polypyrrole and polythiophene films have bee n measured as a function of heat-treatment temperature. From room temperatu re to 150 degreesC, the conductivity of polypyrrole film remained constant. From 150 to 300 degreesC, the conductivity dropped due to the decompositio n of polypyrrole and the loss of dopant ion (ClO4-). Above 300 degreesC, th e conductivity increased again. Above 750 degreesC, the conductivity was hi gher than that of the original film due to the formation of carbonaceous ma terials. The polythiophene film showed a similar tendency to the polypyrrol e film. Chemical and spectroscopic methods such as elemental analysis, FT-I R and ESR were employed to determine the origin of the electric conductivit y changes. (C) 2000 Elsevier Science Ltd. All rights reserved.