Significant increase in conductivity of polydiacetylene thin film induced by iodine doping

A significant improvement of the conductivity of polydiacetylene thin films by iodine doping was observed using independently driven double-tip scanning tunneling microscopy. One-dimensional conduction along the polydiacetylene backbone was obtained and the conductivity of the iodine-doped polydiacetylene thin film was estimated to be (3 ± 0.3) × 10−3 S/cm, which is three orders of magnitude higher than that of the nondoped polydiacetylene thin film and five orders of magnitude higher than that reported previously. The results of visible light absorption spectroscopy and atomic force microscopy showed that distinct changes in the electronic properties of the polydiacetylene backbone in the absence of a close-packed arrangement of polydiacetylene molecules.