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

The way interchain interactions affect the absorption and luminescence properties 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 interacting units. The consideration of α-oligothiophenes in their crystalline structure allows us to shed light into the chain-length evolution of the optical splitting of the lowest optically-allowed excited state and to validate the theoretical approach by confronting the theoretical predictions to experimental results. Various strategies are proposed to prevent luminescence quenching when going from solutions to films or crystals.