| Research Abstract |
White light-emitting organic electroluminescent devices were developed by using dye-dispered polymer emitter layrs and by using a multilayr device structure. In case of the polymer emitter layr, in order to achieve bipolarity in the single polymer emitter layr, hole-transporting poly (N-vinylcarbazole) (PVK) was molecularly dispersed with electron-transporting additives such as 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole. In addition, several fluorescent dyes, having different emission colors, were dispersed aa emitting centers. By adjusting the concentration of the fluorescent dyes, white light with a maximum luminance of 4100 cd/m^2 was obtained, which is the brightest white light ever observed for organic electroluminescent devices. In case of the multilayr trpe, three emitter layrs with different carrier transport properties, each emitting blue, green or red light, are used to generate white light. Bright white light, over 2000 cd/m^2, was successfully obtained. We have also synthesized hole-transporting polymers containing triphenylamine moieties and blue-emitting fluorescent dyes for EL application.
|
