CHARGE-TRANSPORT POLYMERS FOR ORGANIC ELECTROLUMINESCENT DEVICES

Triple-layer-type organic electroluminescent devices were fabricated u sing charge-transporting poly(N-vinylcarbazole) (PVK) as a hole-transp orting emitter layer. Electron-transporting layers consisting of a tri azole derivative (TAZ) and an aluminum complex (Alq) layer were used t o maximize the carrier recombination efficiency. The EL device with a structure of glass substrate/indium-tin-oxide/PVK/TAZ/Alq/Mg:Ag showed bright blue emission from the PVK layer with a luminance of over 700 cd/m2. The emission color was tuned to a desirable color in the visibl e region through doping the PVK layer with fluorescent dyes. Bright wh ite emission, in particular, was obtained for the first time at a high luminance level of over 3000 cd/m2 by using three kinds of fluorescen t dyes each emitting red, green or blue.