Electrical properties of ion implanted polythiophene

Polythiophene as a free standing film has been ion implanted with 25 keV F+ ions. Rutherford backscattering measurements showed that the surface of the film was modified to a depth of 0.4 μm. The dc-conductivity increase was more than 7 orders of magnitude, the highest value being 1.3·10−2 Ω−1cm−1 for a dose of 2·1017 F+/cm². The increased conductivity, which was stable with time was accompanied by a drastic decrease in thermoelectric power which showed metallic-like behaviour. The temperature dependence of conductivity and thermoelectric power points to variable range hopping between localized states caused by the implantation. Electron spin resonance data support the concept of localized charge carriers