Simultaneous alternating current impedance/electron spin resonance study of electrochemical doping in polypyrrole

Abstract

The electrochemical doping of polypyrrole has been studied using simultaneous a.c. impedance and in-situ electrochemical e.s.r. measurements. A quantitative estimate of the polypyrrole conductivity as a function of doping level has been obtained and the corresponding change in the polaron concentration measured by in-situ electrochemical e.s.r. It was found that at low doping levels there was a good correlation between these two properties. It is suggested that the polaron may be responsible for the conduction process under such conditions. At higher doping levels conduction would appear to involve the bipolaron.