RESONANCE RAMAN-STUDY OF POLYTHIOPHENE FILMS IN THE DOPED AND UNDOPEDSTATES - RELATIONS BETWEEN SPECTRAL DATA AND PHYSICOCHEMICAL PROPERTIES

Polythiophene films prepared by electrochemical polymerization of thio phene were analysed, in situ and ex situ, by resonance Raman spectrosc opy using several excitation wavelengths ranging between 457.8 and 106 4 nm. The domain of the polymer reversibility, during oxido-reduction cycles, was strictly defined by in situ experiments and the doping yie ld was correlated with the intensity ratio of two bands at 1411 and 14 28 cm-1 resulting from excitation at 1064 nm. Atomic force microscopy measurements have shown that disorder at the polymer surface is increa sing with the film thickness. It was suggested that the doped parts of the polymer responsible of the cauliflower structure become so import ant that they hide the undoped parts and, thus, could explain the spec tral modifications observed with increasing thickness.