Polymer films on electrodes. 30. Electrochemistry and scanning electrochemical microscopy characterization of benzimidazolebenzophenanthroline-Type ladder (BBL) and semiladder (BBB) polymer films

Polymer-modified electrodes were obtained by spin-coating solutions of poly (benzobisimidazo-benzophenanthroline) ladder (BBL) and semiladder (BBB) pol ymers on indium-tin oxide electrodes. An electrochemical study of these fil ms showed reproducible and stable cyclic voltammograms for reduction of the polymer (in the absence of oxygen), the absence of waves for oxidation of the polymer, and brilliant changes in color during the potential scan. Meas urements with the scanning electrochemical microscope showed changes in the film conductivity, with the films being more conductive in the reduced for m. The potential dependence of the film resistance and atomic force microsc opic characterization are also reported. These results confirm the electron transport and electron-accepting nature of both BBL and BBB, which can acc ept up to two electrons per monomer repeat unit. Although the electrochromi c features of BBL and BBB are similar, a significant difference in the film morphologies was observed by atomic force microscopy.