Doping-dependent studies of the Anderson-Mott localization in polyaniline at the metal-insulator boundary

Abstract

Temperature-dependent dc conductivity measurements and infrared reflectivity measurements (20--9000 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) were performed on a series of polyaniline samples with two different dopant acids at various doping levels. The typical fingerprints of a disordered metal such as a positive temperature coefficient of resistivity at high temperatures, a very high reflectivity in the far infrared, and a plasma resonance have been observed. The results were analyzed in the framework of the Anderson-Mott localization model and considerable consistency between transport studies and optical measurements was obtained. Various parameters enabling a comparative classification of the materials are also reported.