Problems in the study of electro-luminescence devices based on phosphorescent dyes

From the photo-physical and photochemical points of view, the basic problems of phosphorescent emission elect ro-luminescence devices have been discussed briefly in this review. A series of problems such as the emission layer material selection, the exciton formation and its migration within different transportation layer, the energy transfer between host and guest molecules and the condition of phosphorescence emission are involved. Key points concerned with the device design and preparation are also discussed concisely.