Crossover from Mott to Efros-Shklovskii variable-range-hopping conductivity in conducting polyaniline

摘要

Electrical resistance and magnetoresistance of the HCl-doped polyaniline (PANI) in aqueous ethanol have been investigated at low temperature down to 1.8 K and in magnetic field up to 8 T. The weaker temperature dependence of resistivity characterized by the ratio, rho(r)= rho(1.8 K)/rho(300 K) indicates that a better homogeneity and less disorder can be obtained by protonation with HCl in ethanol media. The samples with resistivity ratio lying in the range 10(2) less than or equal to rho(r) less than or equal to 10(3) exhibit a crossover from Mott to Efros-Shklovskii variable-range-hopping (VRH) conduction below 10 K. The Coulomb gap energy has been calculated and is small (0.22-0.04 meV). (C) 1998 Elsevier Science S.A. All rights reserved. [References: 26]