Li+ doping-induced localization in polyaniline

We report that LiCl dopes the emeraldine base (EB) form of polyaniline and produces polyaniline with unusual properties-polyaniline with doping-induce d charge localization, Our assignment of Li+ doping is based upon the obser vation of electronic states in the bandgap and associated spins for EB proc essed with LiCl. However, even at the maximum doping level, LiCl-doped poly aniline is a strongly localized charged insulator based on the observation of low DC conductivity, low dielectric constant, rapid decrease of the osci llator strength to zero in the infrared, low magnetic susceptibility domina ted by a weak Curie component, broad EPR linewidth and predominantly Gaussi an lineshape of the EPR signal. Finally, we attribute these properties to t he formation of bipolarons or antiferromagnetically coupled polaron pairs i n LiCl-doped EB. (C) 1999 Elsevier Science S.A. All rights reserved.