Improvement of Electrical Conductivity of In Situ Iodine-Doped Polypyrrole Film Using Atmospheric Pressure Plasma Reactor with Capillary Electrodes

To improve the electrical conductivity of polypyrrole (PPy) nanostructure film through in situ iodine (I₂) doping, this study proposes an atmospheric pressure plasma reactor (APPR) where heated I₂ dopant vapor is fed through capillary electrodes that serve as electrodes for discharge ignition. A large amount of the heated I₂ vapor introduced into the reactor separately from a monomer gas can be effectively activated by an intense plasma via capillary electrodes. In particular, intensive plasma is obtained by properly adjusting the bluff body position in the APPR. Based on the ICCD and OES results, the I₂ vapor injected through the capillary nozzle electrode is observed to form I₂ charge species. The formed I₂ species could directly participate in growing in situ I₂-doped PPy films. Thus, in situ I₂-doped PPy nanostructure films grown using the proposed APPR exhibit higher thicknesses of 15.3 μm and good electrical conductivities, compared to the corresponding non-doped films.