Charge-transfer exciton state, ionic energy levels, and delayed fluorescence in anthracene

Abstract

Abstract Our work on the delayed electroluminescence of anthracene crystal has shown that the recombination of holes and electrons produces the normal fluorescence of anthracene, and that time dependence of the fluorescence can be modified by an external electric field. We have also shown that the recombination of holes and electrons produces what appears to be an ion-pair or charge-transfer (CT) exciton, that this CT exciton diffuses through the anthracene crystal, and can form a dimer with another CT-exciton; the decay of the dimer produces one photon, at most. The normal decay of the nearest neighbor CT exciton, and the CT-exciton dimer produces a tail that extends into the microsecond region. Some estimates are given for the lifetime of the CT exciton; ionic energy levels for anthracene crystal are also given.