High brightness OLED with dual emitting layers

The bright white organic light-emitting diode can be obtained by using two major organic layers which emit blue and orange-yellow light, respectively. The two emitting organic materials 4,4-Bis(2,2-diphenyl-ethen-1-yl)-biphenyl (DPVBi) and 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminost-yry)-4H-pyran (DCM) doped into Tris(8-quin olinolato) aluminum (DCM:Alq3) are used as a blue emitting and a orange-yellow emitting layer, respectively. The ratios of co-evaporated rate for DCM and Alq3 could be controlled and the thickness of DPVBi was changed to get optimum result for white light. We got the maximum luminance 12,000 cd/m2 at 15 V. The CIE coordinates were (0.3520, 0.2956) operated at 12 V entirely within the white light region in CIE coordinates. The current efficiency at 15 V was 6.7 cd/A. The optimum co-evaporated rate for DCM relative to Alq3 to get orange-yellow emission in co-evaporation was 0.01:1 and the thickness of DPVBi was 35 Å.