A field-dependent organic LED consisting of two new high Tg blue light emitting organic layers:: a possibility of attainment of a white light source

Two new blue light emitting trimeric compounds of the Y-shape type having high glass transition temperatures were synthesized and EL behavior of LED devices consisting of bilayers of the two compounds was studied. One of the compounds is of hole-transporting type containing carbazole moieties, whereas the other is of electron-transporting type bearing phenyloxadiazole moieties. The bilayer LED devices exhibit a strong field-dependence and emit white light (simultaneous light-emittance in blue, green and red regions), at high applied electric fields. Increased interfacial formation of exciplexes at stronger external fields appears to be responsible for this field-dependence.