Electrical conductivity and stability of oxidative chemical vapor deposition copolymer thin films of thiophene and pyrrole

In a single step polymerization and coating, oxidative chemical vapor deposition (oCVD) is used to synthesize copolymers of thiophene and pyrrole. The copolymer composition is controlled simply by adjusting the ratio of the comonomers in the feed. The electrical conductivity of the copolymer is found to be higher than the homopolymer of either comonomer and is more stable in the ambient over the period of three months tested. The enhanced conductivity and stability are attributed to fewer defects and enhanced doping as evidenced by Raman and X-ray photoelectron spectroscopy. Grazing incident angle X-ray diffraction indicates there is no long range order or crystallinity to explain the enhanced electrical properties. Instead, the film synthesis approach and the resulting film chemical environment are believed to be the primary reasons behind the enhanced conductivity of the deposited copolymer films.