Highly ordered and conducting thin film of pentacene doped with iodine vapor

We have demonstrated the iodine doping of vacuum-deposited pentacene (PEN) film which showed characteristic changes in structure and electrical conductivity. The iodine-doped film exhibited a high electrical conductivity of 110 Ω−1 cm−1, which was 11 orders of magnitude larger than that of as-deposited film, and a high electrical anisotropy of 108. The structural changes by the iodine doping were studied by means of x-ray diffraction method, ultraviolet-VIS absorption spectroscopy, and FT-infrared spectroscopy. These results revealed that iodine molecules were intercalated between the layers of PEN molecules to form charge transfer complex of PEN-iodine with highly ordered structure.