• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.291-294
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• 2010

In this study, we demonstrated high-efficiency blue organic light-emitting diodes (OLEDs) employing BCzVBi as a blue fluorescent dye doped into blue host material, DPVBi with various concentration. The optimized blue OLED device having high-efficiency was constructed with structure of NPB (500 ${\AA}$) / DPVBi:BCzVBi-6% (150 ${\AA}$)/$Alq_3$(300 ${\AA}$) / Liq (20 ${\AA}$) / Al (1000 ${\AA}$). The maximum luminescence of blue OLED was 13200 cd/$m^2$ at 13.8 V and current density and maximum efficiency were 26.4 mA/$cm^2$ at 1000 cd/$m^2$ and 4.24 cd/A at 3.9 V, respectively. Luminous efficiency shows two times higher than comparing with non-doped BCzVBi blue OLED whereas $CIE_{x,y}$ coordinate was similar with bare DPVBi blue OLED such as (0.16, 0.19). Electroluminescence of BCzVBi-6% doped blue OLED has two major peaks at 445 nm and 470 nm whereas pure DPVBi's blue peak appears at 456 nm and it is happened through endothermic Forster energy transfer by molecule's vibration between LUMO of DPVBi as host material and LUMO of BCzVBi as dopant in device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.156-156
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• 2010

We have developed highly efficient blue phosphorescent organic light-emitting devices (OLED) with simplified architectures using blue phosphorescent material. The basis device structure of the blue PHOLED was anode / emitting layer (EML) / electron transport layer (ETL) / cathode. The dopant was partially doped into the host layer for investigating recombination zone, current efficiency, and emission characteristics of the blue PHOLEDs.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.486-488
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• 2009

High efficiency deep blue and pure white phosphorescent organic light emitting diodes were developed using a new deep blue phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium (FCNIr). A high quantum efficiency of 9.1 % with a color coordinate of (0.15, 0.16) at 1,000 cd/$m^2$ was obtained in the deep blue device and a high quantum efficiency of 15.2 % with a color coordinate (0.30, 0.32) was obtained in the pure white organic light-emitting diodes. The quantum efficiency of the pure white device is the best quantum efficiency value reported in the pure white device up to now.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.921-924
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• 2008

We investigated new deep blue emitting materials including a novel side group such as CB-203. CB-203 shows relatively 40% increased PL quantum efficiency and higher Tg of $30^{\circ}C$ compared to MADN. It exhibits high External Quantum Efficiency (EQE) of 7.18% that is two times bigger than MADN's, which is the best efficiency in case of non-doped blue fluorescence OLED device to our knowledge. And deep blue emitting materials with a new core structure (CB-301) have been synthesized. CB-301 exhibit excellent blue fluorescence properties. Undoped OLED devices using CB-301 as blue emitters was found to deep blue CIE value (0.154, 0.078) and exhibit high luminance efficiencies of 2.01cd/A at $10\;mA/cm^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1419-1421
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• 2007

Color conversion technology using unique color conversion film for OLED back light was developed to achieve renovative performance for high- end display. It can reduce the production cost more than 20% due to cheaper cost for blue OLED and conversion film and also has a free chromaticity control capability for 10% raising color gamut with respect to LCD color filter. The OLED BLU by color conversion technology also shows excellent performances such as chromaticity stability. White efficiency using PLF + Blue OLED is 17cd/A@4.4V, CIExy(0.29, 0.31).

• Journal of the Korean institute of surface engineering
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• v.48 no.3
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• pp.121-125
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• 2015

We studied the blue fluorescent OLED with Mg:Ag, Al, Ni as anode materials. Blue fluorescent OLEDs were fabricated using Anode / $MoO_3$ (3 nm) / 2-TNATA (60 nm) / NPB (30 nm) / SH-1 : BD-2 (5 vol.%, 30 nm) / Bphen (40 nm) / Liq (1 nm) / Al (150 nm). Current density of OLED with Mg:Ag was not measured due to too low work function, and that of OLED with Al showed $45.2mA/cm^2$ at 12 V. Luminance and Current efficiency of OLED with Al showed $385.1cd/m^2$ and 0.9 cd/A. Current density of OLED with Ni of 8, 10, 12 nm thickness showed 10, 12.9, $37.2mA/cm^2$, respectively. Luminance and Current efficiency of OLED with Ni of 8, 10, 12 nm thickness showed 670.9, 991.2, $1,320cd/m^2$ and 6.7, 7.7, 3.6 cd/A, respectively. Transmittance of Al was 52.2% at 476 nm wavelength and that of Ni of 8, 10, 12 nm thickness was 79, 77, 74 %, respectively. In spite of best current density, OLED with Al showed the lowest luminance and current efficiency because of low work function and poor transmittance. When thickness of Ni was increased to 12nm, current efficiency was sharply lower owing to bad transmittance and unbalance of holes and electrons. Finally, OLED with Ni of 10 nm thicknes showed the highest current efficiency.

• Journal of Information Display
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• v.8 no.1
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• pp.10-13
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• 2007

We synthesized new blue and bluish green emitting materials by using fully substituted ethylene moieties. Multi-layered EL devices were fabricated with synthesized materials and evaluated in terms of emission color and luminescence efficiency. TBBPE[EML 2] device showed bluish-green CIE value of (0.236, 0.412) and 5.02cd/A at $10mA/cm^2$. BPBBPE[EML 3] device also showed sky-blue CIE value of(0.218, 0.355) and 2.31cd/A at $l0mA/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.121-122
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• 2008

Blue emitting materials have been explored by various researchers. However, blue-emitting materials with high luminous efficiency, good color purity, and thermal stability are still much desired. In this study, we synthesized a new blue luminescent material, $SnDP(HPB)_2$ which is low molecular compound and thermal stability. The PL spectrum of $SnDP(HPB)_2$ was observed blue at the wavelength of 447nm. The ionization potential(IP) and the electron affinity(EA) of $SnDP(HPB)_2$ was measured to be 6.7 eV and 3.0 eV, respectively. The fundamental structure of the OLED was ITO/NPB/$SnDP(HPB)_2/Alq_3$/LiF/Al. As a Result, we obtained to enhance the performance of blue OLED.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.281-281
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• 2009

Electrical analysis of red, green and blue (RGB) organic light emitting diode (OLED), which were measured at various temperatures from 230K to 370K by steps of 20K, were investigated using current-voltage(I-V) characteristics. Ideality factor and series resistance were obtained from the thermionic emission theory. Experimental results showed that the ideality factors were 2.12 for red, 3.80 for green, and 6.03 for blue OLED at 290K, respectively. The series resistance were 1960, 2190, 2630$\Omega$ for red, green and blue OLED at the same temperature. It was found that the OLED ideality factors were much higher than near unity for well-behaved silicon diodes, because of the organic material and multi-layer fabrication diode. In addition, the series resistance was near 2k$\Omega$ range. More researches are required to reduce both ideality factors and series resistance to increase the efficiency of OLEDs.

• 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.