ELECTROCHEMICAL STUDIES OF FUSED-THIOPHENE SYSTEMS

A study of the electrochemical polymerization of two and three fused thiophene-ring systems is presented. Thieno[2,3-b]thiophene (TT) and dithieno[3,2-b; 2′,3′-d]thiophene (DTT) can be polymerized electrochemically on conducting glass (SnO₂) or Pt. Poly DTT can be electrochemically oxidized and reduced between the neutral and acceptor doped forms, while poly TT does not show a reduction wave after oxidation. Observed u.v. absorption spectra of poly DTT as a function of oxidation potential resemble that of polythiophene. The complex impedance of poly DTT indicates a decrease in charge transfer resistance as the oxidation potential increases. The limiting capacitance is shown to be closely correlated to the doping level of the polymer.