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We demonstrated hybrid white organic light-emitting diodes (HWOLEDs) using 1,4-bis{2-[7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl)]vinyl} benzene as the fluorescent blue emitter and iridium(III) bis(2-phenylquinoline) acetylacetonate as the phosphorescent red emitter. We also investigated the codoped spacer ratio (CSR) effects of 4,4',4''-tris(N-carbazolyl)-triphenylamine (TCTA) and 2,2',2''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBI) on the electroluminescence characteristics of HWOLEDs. The optimized HWOLED with a CSR of 1:3 (TCTA:TPBI) exhibited a lower efficiency roll-off of 32% than the control device (67%) with a CSR of 1:1 (TCTA:TPBI). The HWOLED also showed a current efficiency of 12.76 cd/A, an external quantum efficiency of 6.95%, and Commission Internationale de I'Eclairage coordinates of (0.38,0.39) at 1000 cd/m2.

The authors have demonstrated hybrid white organic light-emitting diodes (HWOLEDs) with reduced efficiency roll-off. It was shown that HWOLEDs fabricated with {9,9-dimethyl-7-[10-(naphthalen-2-yl)anthracen-9-yl]-9H-fluoren-2-yl} triphenylsilane (ANFTPS) as the blue host have the maximum external quantum efficiency of 9.92%, power efficiency of 14.51 lm/W, and reduced efficiency roll-off 2.0 times that of the control white device. The deep highest occupied molecular orbital of ANFTPS of the optimized white device adequately brocks holes and confines excitons in emitting layers. The white device also exhibited a more stable color shift from low to high current density than did the control white device.

We have demonstrated high-efficiency phosphorescent white organic light-emitting diodes (PHWOLEDs) using iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C 2] picolinate and iridium(III) bis[1-phenyl(quinolinato-N,C 2')]acetylacetonate doped in N,N '-dicarbazolyl-3,5-benzene as a single-host system. As the position of the doped red emitter changed from near the anode to the cathode, the PHWOLED exhibited reduced exciton loss and greater color stability. The optimized PHWOLED exhibited a peak external quantum efficiency of 13.49%, a power efficiency of 20.59 lm/W, a current efficiency of 26.20 cd/A, and Commission Internationale de l'Eclairage coordinates of (0.37, 0.35). The red emitter near the cathode includes efficient triplet energy confinement in the emitting layers.

The authors have demonstrated hybrid white organic light-emitting diodes (WOLEDs) using 1,4-bis[2-(7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl))vinyl] benzene as a fluorescent blue emitter and iridium(III) bis(2-phenylquinoline) acetylacetonate as a phosphorescent red emitter. As the spacer ratio of 4,4',4''-tris-(N-carbazolyl) triphenylamine to 4,7-diphenyl-1,10-phenanthroline changed from 1:1 to 1:3, WOLEDs showed changes from cold to warm electroluminescent characteristics. The optimized WOLEDs of 1:3 spacer ratio showed an external quantum efficiency of 7.40%, a luminous efficiency of 14.79 cd/A, and Commission Internationale de I'Eclairage coordinates of (0.43, 0.39) at 1000 cd/m2.

We have demonstrated high-efficiency white organic light-emitting diodes (WOLEDs) using codoped blue-emitting layers with three light emitters, 4''-(2,2-diphenylvinyl)-1-[4-(N,N-diphenylamino)-styryl]-terphenyl, fac-tris(2-phenypyridine) iridium(III), and bis(5-benzoyl-2-phenylpyridinato-C,N)iridium(III) (acetylacetonate). Blue-emitting layers (BEMLs) were codoped with the different functional materials, N,N'-bis(1-naphyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine and 4,7-diphenyl-1,10-phenanthroline, which are used as charge-transporting materials in OLEDs. An optimized device with centralized carriers in emitting layers showed a maximum luminance of 19 710 cd/m2 at 12 V, a maximum luminous efficiency of 23.20 cd/A at 0.14 mA/cm2, and an external quantum efficiency of 10.20% at 32.19 cd/m2.