Vibrational and electronic spectroscopic study of two oligothiophene materials bearing a heteroquinonoid structure.

We use Raman scattering spectroscopy to probe the fundamental modes of vibrations of two α-linked oligothiophenes having a quinonoid structure in the electronic ground state, in order to get useful information on the charge carriers in doped polythiophene. The electronic absorption spectra of these materials show a very large red-shift of the π-π* electronic transition relative to the aromatic end-capped oligothiophenes of the same number of rings. This observation could be explained by the existence of an intramolecular charge transfer.