The Role of Intermolecular Interactions on the Optical and Charge-Transfer Properties of Conjugated Polymers

We investigate by means of quantum-chemical calculations the influence of intermolecular interactions on the properties of conjugated chains. We first focus on the optical absorption and emission of clusters formed by identical poly(paraphenylene vinylene), PPV, oligomers; we address the role played by the relaxation effects in the lowest excited state as well as the number and relative orientations of the interacting units. Several strategies are suggested that can be developed to avoid a substantial decrease in luminescence quantum yield in the solid state. In a second part, we illustrate by means of a simple theoretical model that charge or energy transfer can take place at the interface between two different PPV derivatives, depending on the nature of the substituents grafted on the PPV backbone,