Functional Molecular Materials Derived from Organic Conducting Polymers

Organic conjugated polymers form a new class of materials in which each macromolecular chain presents a high electrical conductivity. This unique property allows to represent these materials as a tridimensional network of molecular wires, able to carry informations. These wires can be chemically functionalized by the covalent binding of various prosthetic groups, presenting specific interactions whether with the chemical environment or with external physical quantities. Molecular transducers can thus be developed, and examples already exist on the molecular recognition exerted by functionalized conducting polymers toward ions or toward optically active species in solution. These structures open the promising field of molecular electronics, although the development of this new research area first requires the demonstration that the charge transport properties of these materials are efficient enough for them to be used as active layers in electronic devices. This step has been recently achieved, by the development of a new class of organic conjugated materials, conjugated oligomers, which present shorter conjugation length but much lower content of structural defects. The semiconducting properties of these oligomers have been determined through the characterization of field-effect transistors fabricated from these organic materials. A new all-organic thin film architecture has been proposed for these transistors, which shows comparable characteristics to those of a-Si:H based devices. These results confirm that organic conjugated polymers and oligomers can be used as active materials for the construction of electronic devices, and that their further functionalization will allow the development of new types of molecular transducers.