POLY(CYCLOALKYL[C]THIOPHENE)S - SYNTHESES, ELECTRICAL-PROPERTIES AND CHARGE-TRANSPORT MECHANISM

Poly(cycloalkyl[c]thiophene)s were synthesized by electrochemical or chemical oxidation of bicyclic, alpha,alpha'-unsubsituted 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 a 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 a 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 1-10(7) 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.