Two-dimensional electrical transport of pentacene thin films doped with iodine

The logarithmic electrical resistivities of pentacene (PEN) thin films doped with iodine in the direction parallel to the substrate plane fit the T−1/3 dependence well. This indicates that the lateral transport of the film was governed by two-dimensional variable range hopping. In contrast, the logarithmic resistivities of the films perpendicular to the substrate were observed to be almost independent of temperature and to be weakly T−1/2 dependent. This shows that the tunneling mechanism is predominant in perpendicular transport. Two-dimensional conduction of the film was confirmed by these transport properties, which was expected from the intercalated structure of PEN film doped with iodine.