Dielectric permittivity study on weakly doped conducting polymers based on polyaniline and its derivatives

We report the results on low frequency dielectric study of pressed pellets of polyaniline (PAN) and its derivatives in the emeraldine base and weakly doped emeraldine salt forms. The parameter describing the doping is defined as y=[H+]/[N]. The samples were synthesized with y=0.00, 0.07 and 0.50. It is suggested that the presence of polarons and bipolarons are responsible for the dielectric relaxation mechanism as well as the frequency and temperature dependence of conductivity. A broadening in the spectrum of relaxation times of the dielectric relaxation process due to charge motion via creation/annihilation of polarons and bipolarons increases with increasing doping. The subsequent diffusion of polarons and bipolarons become faster as doping increases.