[Mechanism and fluorescence spectra of 5,6,11,12-tetraphenyl-tetracene doped 8-hydroxyquinoline system].

The PL and EL spectra of 5,6,11,12-tetraphenyl-tetracene doped 8-hydroxyquinoline are measured. It is found that Alq is host emitter when dopant concentration is low, and a discrete level is introduced by doping Rubrene (guest emitter) in Alq energy gap. As increasing Rubrene concentration, Rubrene is host emitter but Alq becomes guest emitter. Because overlap between absorption spectrum of Rubrene and emission spectrum of Alq is greater, the energy transfer and charge transfer between host emitter and guest emitter are occurred in PL of doping Alq thin film. As conductive band (LUMO) of Rubrene is much lower than that of Alq, and their valence bands (HOMO) are about the same, and electron concentration of conductive band of Rubrene is much greater than that of Alq, the rate of recombination between the electrons in conductive band and holes in valence band of Rubrene is much greater than in Alq, so EL is mainly emission of Rubrene.