• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.477-480
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• 2008

A highly efficient white phosphorescent OLED with a "tetra-chromatic" emission was fabricated by using an external color tuning layer (ECTL) which is composed of a layer of greenish yellow organic dye dispersed in PMMA on the outside of the glass. The ECTL combining with a lower red dopant concentration in the device has been found to improve the efficiency of a conventional WOLED by more than 27%.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1067-1070
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• 2006

We have demonstrated highly efficient WOLED with two separated emissive layers using a blue fluorescent dye and a red phosphorescent dye. The maximum luminous efficiency of the device was 11.2 cd/A at $20\;mA/cm^2$ and $CIE_{x,y}$ coordinates varied from (x = 0.33, y = 0.37) at 6V to (x = 0.25, y = 0.33) at 14V.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1002-1005
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• 2006

In this study, we fabricated white organic light emitting devices (WOLEDs) to use single emission layer, DPVBi with partially doped Rubrene. To realize white color, rubrene with 3.6% was partially doped with the gap from interface between DPVBi and hole transport layer NPD in a definite DPVBi layer. As the gap was increased, the intensity of orange peak grows less and less. The WOLED with gap of $5\;{\AA}$ has the best color stability and its color coordination is (0.345, 0.321) at 6V.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.820-822
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• 2009

Tandem white organic light emitting diodes (WOLEDs) are fabricated by using a transparent interconnecting layer of Al:LiF composite/molybdenum oxides ($MoO_3$). We demonstrate two types of tandem WOLEDs consisting of two color emissions (red and blue emission) and three color emissions (red, green and blue emission). Tandem WOLED consisting of three color emission shows higher external quantum efficiency and current efficiency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.124-127
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• 2010

We have fabricated organic white light emitting device by two colors from yellow fluorescence material (5,6,11,12)-Tetraphenylnaphthacene(Rubrene) and blue phosphorescent material (iridum-bis(4,6-difluorophenylpyridinato-N,C2)-picolinate(FIrpic). The threshold voltage is 5.3 V, and the brightness reaches 1000 cd/$m^2$ at 11 V, 14.5 mA/$m^2$. The color of the light corresponds to a CIE coordinate of (0.30, 0.38). The highest efficiency of the device can reach 9.5 cd/A or 5.5 lm/W at 6 V, 0.1 mA/$m^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.493-494
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• 2006

We have demonstrated highly efficient WOLED with two separated emissive layers using a blue fluorescent dye and a red phosphorescent dye. we also obtain stable $CIE_{x,y}$ coordinates with two-layered WOLEDs. The device structure was ITO/2-TNATA/NPB/two separated emissive layers/Bphen/Liq/Al. The maximum luminous efficiency of the device was 11.6 cd/A at $20\;mA/cm^2$ and $CIE_{x,y}$ coordinates varied from (x = 0.33, y = 0.37) at 6V to (x = 0.28, y = 0.35) at 14V.

• Journal of Information Display
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• v.9 no.3
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• pp.23-27
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• 2008

This paper reports that well-balanced white emission with three primary colors can be achieved with a simple white organic light-emitting diode (WOLED) structure of ITO / $\alpha$-NPD (50 nm) / $\alpha$-NPD: Btp2Ir(acac) (8 wt%, 6 nm) / $\alpha$-NPD (5 nm) / BCP (3 nm) / $Alq_3$: C545T (0.5 wt%, 10 nm) / $Alq_3$ (40 nm) / LiF (0.5 nm) / Al (100 nm). The external quantum efficiency of the device reached 3.8% at a current density (luminance) of 4.6 mA/$cm^2$ (310 cd/$m^2$), and the maximal luminance of the device reached 19,000 cd/$m^2$ at 11.5 V. The insignificant blue shift of the emitting color with an increasing current density can be attributed to the narrowing of the exciton formation zone width.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.185-190
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• 1988

The study was designed to establish quantitative method for assessing the marginal leakage of dental restorations. 18 Class V cavities with $45^{\circ}$ bevel joint were prepared and replicas of these teeth were made with polyethylene wax. and classified with three groups. First group was filled with Scotch bond and silux. Second group was filled with glass ionomer cement:scotchbond/silux. Third group was filled with Dentin-Adhesit/Heliosit. After finishing, all specimens were subjected manually to 100 thermal cycles at $0^{\circ}C$ and $100^{\circ}C$ Samarium nitrate solution, irradiated with flux of $6{\times}12^{12}$ neutrons/$cm^2$/sec for 11 hours, woled for 200 hours, counted with the HpGe detector and the tracer uptake was determined by comparison with a standard of samarium ($10{\mu}g$). The following results were obtained. 1) The group filled with glass ionomer cement base showed least marginal leakage. 2) The group filled with Dentin-Adhesit/Heliosit showed less marginal leakage than the group filled with scotchbond/silux.

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

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1437-1439
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• 2007

We fabricated white organic light emitting device (WOLED) with the layered fluorescent blue material and phosphorescent green/red dye-doped materials. Addition of the non-doped phosphorescent host material between the fluorescent and phosphorescent light emitting layers provided the result of broadband white spectrum, with improved balance, higher efficiency, and lower power consumption. In our devices, there was no need of exciton-blocking layer between the each emission layer for the further confinement of the diffusion of excitons.