• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.1
• /
• pp.15-21
• /
• 2012

In this study, the characteristics of the 2-wavelength white organic light-emitting diod (WOLED) with two colors of yellow and blue were compared and analyzed with 3-wavelength WOLED with three colors of red, green, and blue. The results indicated that the power efficiency of the 2-wavelength WOLED was 1.6 times higher than 3-wavelength WOLED. In addition, the colot coordinate of the 2-wavelenth WOLED which was (0.34, 0.39) was found closer to the optimal color coordinate for the white-lighting application when compared with that of the 3-wavelength WOLED.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.10
• /
• pp.2299-2302
• /
• 2009

By controlling the number of electrons transferred to the emitting layer, highly efficient three-wavelength WOLEDs were fabricated. Such WOLEDs are different from those made using simple stacking of RGB emitting layers in that the movement distribution of electrons transferred to emitting layer could be adjusted using the difference in LUMO energy level and that lights of all 3 wavelengths could be emitted through appropriate arrangement of RGB emitting layers. WOLED device with the structure of m-MTDTA (40 nm)/NPB (10 nm)/ Coumarin6 doped $Alq_3$ (3%) (8 nm)/ Rubrene doped NPB (5%) (15 nm)/NPB (2 nm)/ DPVBi (20 nm)/$Alq_3$ (20 nm)/LiF (1 nm)/Al (200 nm) showed high luminance efficiency of 8.9 cd/A and color purity of (0.31, 0.40). In addition, WOLED device with the thickness of non-doped NPB layer increased from 2 nm to 3 nm to increase blue light emission showed a luminance efficiency of 7.6 cd/A and color purity of (0.28, 0.36).

• Journal of the Semiconductor & Display Technology
• /
• v.10 no.1
• /
• pp.23-26
• /
• 2011

New organic light-emitting diodes with structure of ITO/DNTPD/TAPC/$Bebq_2/Bebq_2$:RP-411/ET-137/LiF/Al using the selective doping of 5% RP-411 in a single $Bebq_2$ host in the two wavelength(green, red) emitter formation were proposed and characterized. In the experiments, with a 300${\AA}$-thick undoped emitter of $Bebq_2$, three kinds of devices with different thicknesses of 30${\AA}$, 40${\AA}$ and 50${\AA}$ in the doped emitter of $Bebq_2$:RP-411 were fabricated. The electroluminescent spectra showed two peak emissions at the same wavelengths of 511 nm and 622 nm for the fabricated devices. When the device with a 30${\AA}$-thick doped emitter is referred as "D-1", the device with a 40${\AA}$-thick doped emitter is referred as "D-2" and the device with a 50${\AA}$-thick doped emitter is referred as "D-3", the relative intensity of 622 nm to 511 nm at two wavelength peaks was higher in the D-2 and the D-3 than in the D-1. The devices of D-1, D-2 and D-3 showed the color coordinates of (0.43, 0.46), (0.46, 0.44) and (0.48, 0.43) on the CIE chart, respectively.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.2
• /
• pp.80-83
• /
• 2011

We have fabricated phosphorescent white organic light-emitting devices (WOLEDs) with a spin-coated poly(Nvinylcarbazole) [PVK] host layer. Iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,$C^{2'}$]picolinate (FIrpic), tris(2-phenylpyridine)iridium(III) [$Ir(ppy)_3$], and tris(2-phenyl-1-quinoline)iridium(III) [$Ir(phq)_3$], were used as the blue, green, and red guest materials, respectively. The PVK was mixed with FIrpic, $Ir(ppy)_3$, and $Ir(phq)_3$ molecules in a chlorobenzene solution and spin-coated in order to prepare the emission layer; 3-(4-biphenylyl)-4-phenyl-5-(4-tertbutylphenyl)-1,2,4-triazole (TAZ) was used as an electron transport material. The resultant device structure was ITO/PVK:FIrpic:$Ir(ppy)_3:Ir(phq)_3$/TAZ/LiF/Al. The electroluminescence, efficiency, and electrical conduction characteristics of the WOLEDs based on the doped PVK host layer were investigated. The maximum current efficiency of the three wavelength WOLED with the doped PVK host was 19.2 cd/A.