Blue light-emitting organic electroluminescent devices

Organic electroluminescent (EL) devices with multilayered thin-film structures which emitted bright blue light were constructed. Two empirical guides for the selection of blue-emitting materials were established. The keys to obtain the EL cells with high EL efficiency were excellent film-forming capability of an emitter layer and the appropriate combinations of emitter and carrier transport materials for avoiding the formation of exciplexes. In one of our organic electroluminescent devices, blue emission with a luminance of 700 cd/m² was achieved at a current density of 100 mA/cm² and a dc drive voltage of 10 V.