• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.817-819
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• 2009

We have developed highly efficient blue phosphorescent organic light-emitting devices (PHOLEDs) with simplified architectures using new host materials. The Blue PHOLED with new host:FIrpic emitting layer exhibits a maximum luminance efficiency of 34 cd/A and a low operating voltage 5 V at a high luminance of 1212 cd/$m^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.1019-1022
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• 2007

High efficiency in Phosphorescent Organic lightemitting diodes using carbazole type exciton blocking layer were investigated and detailed mechanism for light emission process was studied. Efficiency of green PHOLEDs was enhanced by a factor 3.7.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.427-430
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• 2007

Phosphorescent OLED technology is a core technology driver for OLED display and lighting products due to the inherent and demonstrated efficiency advantages. Here we present recent results in our continued advancements of PHOLED power efficiency and operational stability with focus on narrowing emission line-width, reducing voltage, and overall design for maximizing device lifetime.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.157-164
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• 2008

The optical characteristcs and visibility of emergence esit signs made with phosphorescent materials have been studied and compared with conventional signs. The phosphorescence of the materials meets standards as defineds by JIS, and achieved a level of brightness recognizable by the human eye. The visibility in the dard of the signs using the phosphorescent materials was shown to be higher than that of currently employed materials. It was confirmed that phosphorescent materials show excellent promise to improve the visibility of emergency exit signs.

• Journal of Information Display
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• v.12 no.3
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• pp.141-144
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• 2011

To improve the performance of blue fluorescent and green phosphorescent organic light-emitting diode devices, Merck developed novel green phosphorescent host and electron-transporting materials. The newly developed electron-transporting material improves the external quantum efficiency of blue fluorescent devices up to 8.7%, with an excellent lifetime. In combination with the newly developed host materials, the efficiency of green phosphorescent devices can be improved by a factor of 1.7, and the lifetime by a factor of 7.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.178-181
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• 2001

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiencies due to the requirement of spin-symmetry conservation. By using the phosphorescent material, the internal quantum efficiency can reach 100 %, compared to 25 % in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, Ir(ppy)$_3$ (tris(2-phenylpyridine)iridium). The devices with a structure of ITO/TPD/Ir(PPy)$_3$ doped in the host material/BCP/Alq$_3$/Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of Ir(PPy)$_3$ and the host materials, we fabricated several devices and investigated the device characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.153-153
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• 2010

We have developed blue phosphorescent organic light emitting diode using spin-coated poly(9-vinylcarbazole) (PVK) host layer doped with blue phosphorescent material, Iridium(III) bis(4,6-difluorophenyl)-pyridinato-N,C2) picolinate (FIrpic). the concentration of FIrpic dopants was varied from 2% to 10%. The electrical and optical characteristics of the blue phosphorescent OLED with PVK:FIrpic layer were investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.94-97
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• 2002

We report highly efficient phosphorescent-dye-doped polymeric light-emitting devices. The devices consist of a polymeric light-emitting layer comprising the phosphorescent dye, host, and matrix polymers. We patterned the phosphorescent-dye-doped polymeric layer with the LITI technique. The devices showed high efficiencies and good pattern quality to adapt to the development of full-color electroluminescent (EL) devices.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.196-199
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• 2009

We report the multiple quantum well (MQW) structure for highly efficient red phosphorescent OLEDs. Various triplet quantum well devices from a single well to five quantum wells are realized using a wide band-gap hole and electron transporting layers, narrow band-gap host and dopant material, and charge control layers (CCL). The maximum external quantum efficiency of 14.8 % with a two quantum well device structure is obtained, which is the highest value among the red phosphorescent OLEDs using same dopant.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.188-191
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• 2009

A high efficiency deep blue phosphorescent organic light-emitting diode (PHOLED) was developed using a new wide triplet bandgap host material (PPO1) with a phenylcarbazole and a phosphine oxide unit. The wide triplet bandgap host material was synthesized by a phosphornation reaction of 2-bromo-Nphenylcarbazole with chlorodiphenylphosphine. A deep blue emitting phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine)iridium (FCNIr), was doped into the PPO1 host and a high quantum efficiency of 17.1 % and a current efficiency of 19.5 cd/A with a color coordinate of (0.14,0.15) were achieved in the blue PHOLED. The quantum efficiency of the deep blue PHOLED was better than any other quantum efficiency value reported up to now.