Evidence of small-polaron formation in polypyrrole

Abstract

The DC conductivity of BF4--doped polypyrrole films has been measured in the temperature range 77-305 K and could be well represented by Mott's variable-range hopping mechanism. The conductivity data were used to extract the coupling constant gamma , the effective polaron mass mp, the effective dielectric constant epsilon p the Debye temperature Theta D, the polaron radius rp, the hopping distance R, the density of states at the Fermi level N(EF) and the hopping energy W, whose magnitudes confirm the formation of small polarons in polypyrrole.