| Recently organic materials have sparked a great deal of interest for their potential use in electroluminescent (EL) displays and thin film light emmiting diodes (LED's). Light emitted from these organic materials is produced by the radiative decay of singlet excitons formed by way of charge carrier injection or photoexcitation. Any reactions which cause these excitons to decay nonradiatively will reduce the luminescence quantum efficiency of the material and hence, the optimum performance of electroluminescent devices. Therefore, an understanding of exciton interactions directly associated with luminescence quenching is vital before we can effectively exploit these devices for technological applications.;In this thesis we have examined the underlying mechanisms of various reactions which can produce a low luminescence quantum efficiency in tris(8-hydroxyquinoline) aluminum (Alq;Our experimental results are summarized as follows: (i) We have examined exciton-exciton interactions due to the formation of a high concentration of singlet excitons. Measurements show that such reactions reduce the photoluminescence (PL), radiative excited state lifetime and PL quantum efficiency in Alq... |
