Two-photon excited fluorescence of donor-acceptor conjugated organic materials in crystalline form

摘要

Several organic materials were found to possess high efficiency two-photon excited fluorescence in crystalline form. They do not display considerable molecular two-photon absorption (TPA) resonance that is due to intramolecular charge transfer. The crystal structures of the compound were investigated. It was determined that tight stacking packing of molecules in all crystals with short distances between stacking planes results in high degree of pi-orbital overlap between molecules. These pi-systems interactions lead to new electronic states and, we believe, responsible for the fluorescent properties in the crystals.