Polythiophenes: A Chance for Maximum Conductivity?
Starting with doped polyacetylene as the “prototype” and the most highly conductive polymer known, the main challenges in the development of a technically useful industrial product are given by the intrinsic drawbacks of polyacetylene: its air sensitivity and the missing processability of the doped, π-conjugated polymer. Practically from the beginning the most promising approach to overcome these drawbacks was to stabilize the sensitive π-electron system by heteroatoms in electron-donating substituents or as polymer chain atoms. The latter has been realized only in polyaniline, whereas the rst approach is offering more different options-the most interesting substituents being N and S, incorporated in a heterocyclic conjugated structure (Figure 3.1). As pointed out in Chapter 1, polypyrrole has been broadly investigated and found certain industrial usage as conductive polymer anode in capacitors and corrosion inhibitor in base coatings. Both polymers suffer from their intense color and therefore insufcient transparency in thin lms, which prohibits several potential applications.