Comparison of electronic transport properties of soluble polypyrrole and soluble polyaniline doped with dodecylbenzene-sulfonic acid

The temperature dependences of the conductivity of soluble polypyrrole (PPy) and soluble polyaniline (PANI) films doped with dodecylbenzene-sulfonic acid (DBSA) have been studied. The room temperature conductivities of samples were 1-8 and 95-100 S/cm, with resistivity ratio ρ_r=ρ(20 K)/ρ(300 K)~10⁴ and ρ_r=ρ(1.4 K)/ρ(300 K)~32 for PPy-DBSA and PANI-DBSA, respectively. At low temperatures, the temperature dependence follows the σ(T)=σ₀exp[-(T₀/T)^m] law, which has been explained within the framework of granular metals model (m=0.5) for PPy-DBSA and Mott's variable range hopping model (m=0.25) for PANI-DBSA. The magnetoresistance of PANI-DBSA is positive and follows H² and H^1/3 dependencies at low and high magnetic fields, respectively; the magnitude of the magnetoresistance is strongly temperature dependent.