Conducting state of polyaniline films: Dependence on moisture

The moisture dependence of the conducting properties of polyaniline films doped with camphor sulfonic acid is reported. Samples characterized as lying in the metallic and critical regimes of the metal-insulator transition have been studied for electrical resistivity in the temperature range 77-353 K under different thermal conditions. Thermal annealing is shown to increase the resistivity and also its temperature dependence. Additionally, the temperature above which the resistivity indicates metallic characteristics is shown to depend very sensitively on the presence of moisture. The results are interpreted using both the inhomogeneously and homogeneously disordered metal models.