Optical properties and photoexcitations of an organic blue emitter embedded in a polymeric active matrix

The doping of a widely used active polymeric matrix, the polyvinyl carbazole (PVK) with a novel organic blue emitter has been studied by both continuous wave and time resolved photoluminescence spectroscopy. It is found that the overall emission efficiency of the blend is controlled by two processes, the resonant transfer from the donor to the acceptor and the hopping between the donor sites. Because of the observed spectral variations of the emission spectrum of PVK (donor) with the temperature, both processes exhibit a strong, albeit opposite temperature dependence. The existence of the hopping process accounts for the sharp increase of the transfer efficiency with the concentration, not predicted by the Foerster theory.