Fully protonated polyaniline: Hopping transport on a mesoscopic scale

Abstract

In order to clarify the transport mechanism in fully protanated highly conductive polyaniline the origin and size of the electronic localization centers and barriers have to be determined. Dispersions of polyaniline in an insulating polymer have been studied by temperature-dependent broadband dielectric spectroscopy (5 Hz to 2 GHz, 100–320 K). The electronic transport in the blends and in pure polyaniline is shown to be governed by three-dimensional (3D) hopping between mesoscopic crystalline regions surrounded by amorphous polyaniline and not by intermolecular hopping or molecular scale disorder. Two independent approaches yield an average size of 8 nm for the metallic regions in polyaniline with 3D extended electron wave functions. The barrier width is estimated to be 1.6 nm. The crystalline metallic regions with an amorphous shell correspond to the primary particles which were found in morphological studies.