DIFFERENT STEPS IN ELECTRODEPOSITION OF POLY(3-METHYLTHIOPHENE) FILMS ON PLATINUM-ELECTRODES STUDIED BY ELLIPSOMETRY, SEM AND AFM TECHNIQUES

AFM and SEM analyses are correlated with chronoamperometric and ellipsometric measurements to describe several steps hi the poly(3-methylthiophene) (PMeT) electrodeposition process. First step: A large amount of oligomers are formed near the electrode surface making the solution strongly absorbing. The nucleation does not occur at the same time on all the crystallites of a well-annealed platinum polycrystal and the structure of the deposited species depends on the crystallite surface orientation. In all cases the deposit is an ordered crystalline one. Second step: A crystalline fibrous film grows, the fibres becoming thicker and thicker. They are first stacked layer by layer; then they grow in a disordered way. Third step: At the tip of the fibres a granular structure appears progressively. The grains in the dedoped film are conglomerates of smaller granules which split up during the doping process.