SPECTROELECTROCHEMISTRY OF ELECTROGENERATED TETRATHIAFULVALENE-DERIVATIZED POLY(THIOPHENES) - TOWARD A RATIONAL DESIGN OF ORGANIC CONDUCTORS WITH MIXED CONDUCTION

Thin films of tetrathiafulvalene (TTF) derivatized polythiophenes were prepared by electropolymerization of precursors based on bithiophene or hybrid thiophene-ethylenedioxythiophene (EDOT). The cyclic voltammo gram of these polymers exhibits an additional anodic wave between the two oxidation steps corresponding to the formation of the TTF cation r adical and dication. The electrochemically induced spectral changes as sociated with these various oxidation processes were analyzed on equil ibrated films and in dynamic conditions using classical and time-resol ved spectroelectrochemical techniques. In spite of a complex behavior due to the overlap of the various TTF oxidations with the doping proce ss of the pi-conjugated supporting PT backbone, the different monomeri c and dimeric oxidized TTF species present in the polymers were unequi vocally identified. Comparison of the two polymers shows that whereas for poly(1) oxidation of TTF precedes the PT doping, the presence of E DOT in the PT backbone of poly(2) leads to the reverse situation. On t he basis of these results, the structural conditions required to devel op a novel class of organic conductors with mixed conduction are discu ssed.