A theoretical insight into the solid-state optical properties of luminescent materials: the supermolecular approach

The way interchain interactions affect the absorption and luminescence prop erties of organic conjugated materials is addressed by means of correlated quantum-chemical calculations on molecular aggregates. Special emphasis is given to the influence of chain length and relative positions of the intera cting units. The consideration of alpha -oligothiophenes in their crystalli ne structure allows us to shed light into the chain-length evolution of the optical splitting of the lowest optically-allowed excited state and to val idate the theoretical approach by confronting the theoretical predictions t o experimental results. Various strategies are proposed to prevent luminesc ence quenching when going from solutions to films or crystals. (C) 2000 Aca demie des sciences/Editions scientifiques et medicales Elsevier SAS.