ELECTROCHEMICAL POLYMERIZATION OF OLIGOTHIOPHENE DERIVATIVES AND THEIR DOPING PROPERTIES

Preparation of high-quality conducting poly(trans-TTTE) and poly(trans-BTTTE) by the electrochemical polymerization of oligothiophene derivatives such as trans-(thiophene-2-yl)-(2,2':5'2''-terthiophene-5-yl)ethylene, trans-TTTE, and trans-(2,2'-bithiophene-5-yl)-(2,2':5'2''-terthiophene-5-yl)ethylene, trans-BTTTE have been carried out. Evidence for electrochemical p-type doping of poly(trans-TTTE) and poly(trans-BTTTE) is obtained from in situ measurements of the cyclic voltammetry, optical absorption spectroscopy and electron spin resonance. These results are tentatively explained in terms of a conformation change in the molecular structure, such as a difference in the torsion angle between neighboring thiophene rings due to the introduction of vinylene groups and are discussed in terms of polaron and/or bipolaron model.