Conducting Langmuir-Blodgett films of polyaniline: Fabrication and charge transport properties

The fabrication, optical and electrical properties of conducting polyaniline Langmuir-Blodgett (LB) films are reported. The films were deposited directly in the doped form by using acidic subphases. The subphase contained either HCl or camphorsulfonic acid leading to LB films with the corresponding counter-ions. Conducting doped LB films are obtained for pH = 2.0, and the doping level decreases with increasing pH. Furthermore, our results show that addition of a neutral salt, KCl, increases the doping level. The conductivity was studied as a function of the number of layers, temperature and electric field. We found that the charge transport takes place by three-dimensional variable-range hopping in a parabolic Coulomb quasi-gap.