Organic Electroluminescence Devices Based on Mixture of Aluminum–Hydroxyquinoline Complex and Compound with Low Dielectric Constant

Abstract

The quantum efficiency and lifetime of fluorescence of an aluminum–hydroxyquinoline (Alq3) complex in solution increased with decreasing polarity of the solvent. Similarly, the fluorescence quantum efficiency and lifetime of Alq3 films were increased by mixing the complex with a compound with a low dielectric constant. These results suggested that the nonradiative decay process of Alq3 is retarded in less polar media. The quantum efficiency and lifetime of fluorescence of Alq3 films were 20±2% and 17 ns, respectively. When Alq3 was mixed with a less polar substance in the film state, the quantum efficiency and lifetime were increased to 25±2% and 20 ns, respectively. These results indicate that the nonradiative decay process in the film state is also retarded as the polarity decreases. Using a film consisting of Alq3 and a compound with a low dielectric constant as the light emitting layer of organic electroluminescence devices, the luminance efficiency was increased by about 20%.