Poly(cycloalkyl[c]thiophene)s — syntheses, electrical properties and charge transport mechanism

Abstract

AbstractPoly(cycloalkyl[c]thiophene)s were synthesized by electrochemical or chemical oxidation of bicyclic, α,α′‐unsubstituted thiophenes. NMR measurements on neutral, soluble poly(cyclododeca[c]thiophene) indicate that the polymers have the expected linear structure. The optical spectra and the electrochemical properties of the films are reported. The electrical conductivity σ of salts of the polymers varies from 50 S/cm to 8 · 10−5 S/cm depending on the ring size of the substituent and degree of oxidation of the polymer backbone. A linear correlation between log σ and the diameter of the alkyl substituent demonstrates that interchain contacts play a dominant role in the conductivity of these polymers. The temperature dependence of the conductivity was measured in the range of 300 to 5 K and its frequency dependence in the range of 1–107 Hz at 300 to 120 K. The conductivity data were analyzed in terms of hopping of localized charge carriers and the localization length of the charge carriers was calculated.