ELECTROLUMINESCENCE IN SEMICONDUCTING CONJUGATED POLYMERS AND OLIGOMERS - A QUANTUM-CHEMICAL APPROACH

We discuss in this contribution the ability of quantum-chemical calcul ations in describing essential aspects of one of the most promising ap plications of semiconducting conjugated polymers, i.e. their use as ac tive layers in light-emitting diodes. We present an overview of the re sults of recent theoretical studies that we have performed on oligomer s representative of polyparaphenylene vinylene and polythiophene. We m ostly deal with: (i) the modelling of the linear optical properties of the conjugated polymers involved in the emitting layer, taking into a ccount the vibronic structure; (ii) the investigation of the relative locations of, and relaxation phenomena taking place in, the lowest sin glet and triplet excited states; and (iii) a general discussion of the various terms contributing to the polaron-exciton binding energy.