Doping and conductivity studies on poly(p-phenylene vinylene)

We have investigated the doping and temperature dependence of the conductivity of poly(p-phenylene vinylene) (PPV) free-standing films. High conductivities and a very weak temperature dependence are obtained in sulfuric acid (H2SO4) -doped PPV (104 S/cm), indicative of a metallic state, whereas iron trichloride (FeCl3)-doped samples are observed to be less conducting (103 S/cm) and insulating at low temperatures. Doping of PPV with triflic acid (CF3SO3H) results in a high conductivity as well. Conductivity as a function of stretching ratio is obtained in H2SO4-doped PPV. The stability of this system in air and moisture was also investigated. These features of PPV as a highly doped conducting polymer system are discussed and compared with previous studies of PPV and of polyacetylene.