Polaronic hopping conduction in poly(N-methyl pyrrole-pyrrole) copolymer

Abstract

Abstract The measured ac conductivity σm(ω) and dielectric constant e′(ω) of lightly doped poly(N-methyl pyrrole-pyrrole) copolymer were investigated in the temperature range 77-350K and in the frequency range 100 Hz-100kHz. At low temperatures, the measured ac conductivity shows a strong dependence on frequency and is almost independent of temperature and can be described by the relation [sgrave](ω)=Aω s , where the exponent s is found to be less than unity. The observed temperature and frequency dependence of the ac conductivity [sgrave](ω) can be qualitatively explained by considering contributions from two mechanisms, one giving a linear dependence of conductivity on frequency and the other giving rise to a broad dielectric loss peak having a distribution of relaxation times. At high temperatures the dielectric constant shows a frequency dispersion consistent with Debye-type relaxation. The origin of this relaxation was critically analysed. The estimated value pf site spacing d calculated from the die...