Excited-state electronic structure of conjugated oligomers and polymers:: A quantum-chemical approach to optical phenomena

In this Account, we have conveyed that quantum-chemical calculations can now address in a realistic way the nature of the lowest-lying excited states and the optical properties of conjugated polymer and oligomer chains of large size. Moreover, it has become possible to investigate in depth the impact of interchain interactions, well beyond the approximation of the point-dipole approach and Kasha's model. We are confident that these advances will open the way to the calculation of other important materials properties. For instance, the quantum-chemical investigation of the interactions taking place between chains of different chemical nature should allow one to define the basic features leading to electron - hole separation in the lowest-lying excited state(s) and the design of photovoltaic devices. The better grasp on interchain interactions should also result in the quantum-chemical determination of electron and hole mobilities within well-ordered structures (at least on a semiquantitative basis), thereby providing an access to transport properties.