Optical conductivity of doped polyaniline: Effects of disorder

Variation of the solvent used in processing doped polyaniline (PAN) films produce a wide range of crystallinity and de conductivity. The conductivity at optical frequencies shows how oscillator strength is shifted from strongly bound localized polaron states to weakly bound conduction states with improved structural order. The effective mass (m∗) decreases with increasing order, showing that the effective bandwidth for the weakly localized conduction states is larger. With further improvements in processing, a significant fraction of the conduction electrons become delocalized.