• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.316-316
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• 2011

유기발광소자는 빠른 응답속도, 고휘도 및 면발광의 장점을 가지고 있어서 차세대 디스플레이와 조명시장에서 주목을 받고 있다. 그 중 백색유기발광소자는 차세대 조명과 디스플레이의 백라이트로서 많은 연구가 진행되고 있으며, 다른 디스플레이에 비해서 많은 장점을 가지고 있다. 그러나 백색유기발광소자의 경우 복잡한 구조에 의한 공정비용의 증가, 낮은 효율 및 색안정성과 같은 문제점이 있다. 본 연구에서는 청색 인광 물질을 사용하여 고효율의 청색 유기발광소자를 제작하였으며, 졸-겔 방법으로 제작된 Mn 도핑된 $Zn_2SiO_4$ 녹색 무기물 형광체와 Mn 도핑된 $CaAl_{12}O_{19}$ 적색 무기물 형광체를 제작된 청색 유기발광소자에 도포하여 백색 발광소자를 제작하였다. Mn 도핑된 $Zn_2SiO_4$와 Mn 도핑된 $CaAl_{12}O_{19}$ 무기물 형광체층은 청색 유기발광소자에서 발생하는 빛을 흡수하여 적색과 녹색의 빛으로 변환하기 때문에 백색 구현에 필요한 청색, 녹색, 적색의 빛을 모두 얻을 수 있다. 녹색과 적색의 무기물 형광체의 두께와 결정크기에 따른 광학적 특성 변화를 조사하여 최적의 백색 발광소자를 제작하였다. 주사전자현미경을 통해 무기물 형광체의 결정크기를 조사하였으며, 전압-휘도 특성으로 광학적 특성을 조사한 결과 제작한 백색 발광소자의 색좌표가 순백색에 가까운 값을 나타내었다. 색변환층으로 사용한 무기물 형광체의 구조적 및 광학적 성질에 대한 결과를 바탕으로 백색 유기발광소자의 발광메커니즘을 설명하였다.

• Journal of the Korean Applied Science and Technology
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• v.18 no.3
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• pp.186-190
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• 2001

By fabricating the organic light-emitting devices (OLEDs) based on 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 $Ir(ppy)_{3}$, we fabricated several devices and investigated the device characteristics. OLEDs doped into BCP by 10% showed the best characteristics. For 10% doped OLEDs, the maximum luminance of was over 10000 $cd/m^{2}$, and the maximum power efficiency was 7.14 lm/W.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.781-785
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• 2009

We have fabricated simple triple-layer blue-emitting phosphorescent organic light emitting diodes (OLEDs) using different thicknesses (25 and 55 nm) of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) electron transport layers. 1,1-bis[4-bis (4-methylphenyl)- aminophenyllcyclohexane (TAPC), bis[(4,6-di-fluorophenyl)-pyridinate-$N,C^{2'}$]picolinate (FIrpic) and N,N' -dicarbazolyl-3,5-benzene (mCP) were used as hole transport, blue guest and host materials, respectively. The driving voltage, electroluminescence (EL) efficiency and emission characteristics of devices were investigated. The maximum EL efficiency was 20 cd/A in the device with 55 nm BCP layer, which efficiency was about 33% higher than the device with 25 nm BCP layer. The higher efficiency in the 55 nm BCP device resulted from the enhanced electron-hole balance. In the EL spectrum of blue phosphorescent OLED with BCP layer, the relative intensity between 470 and 500 nm peaks was related to the location of emission zone.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.427-428
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• 2008

New high efficiency green light emitting phosphorescent devices with emission layers of [TCTA/TCTA:TAZ/TAZ]:Ir$(ppy)_3$ have been fabricated and evaluated in this paper. Among the devices having different thicknesses of TCTA:TAZ mixed layer in the total 300$\AA$-thick host of TCTA(80$\AA$)/TCTA:TAZ (50~100$\AA$)/TAZ, the device with host of TCTA(80$\AA$)/TCTA:TAZ(90$\AA$)/TAZ(130$\AA$) showed the best electroluminescent characteristics with the current density of 95 mA/$cm^2$ and luminance of 25,000 cd/$m^2$ at an applied voltage of 10V. The maximum current efficiency was 52 cd/A under the luminance of 400 cd/$m^2$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.188-192
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• 2015

Gemological and spectroscopic properties of HPHT synthetic diamonds from New Diamond Technology (NDT) company in St. Petersburg (Russia) were examined. Their color (colorless, near-colorless with some boron and Fancy blue with high boron content) and clarity ($VVS-SI_1$) grades were comparable to those of top natural diamonds. NDT synthetic diamonds fluoresced and phosphoresced blue or orange under SWUV light. Photoluminescence spectra revealed H3 center with very small intensity and NV centers. The intensity of H3 in NDT synthetic diamond has very weak in comparison with natural one. Using a combination of gemological and spectroscopic tests, gem-quality synthetic diamonds from NDT can be distinguished from natural diamonds of similar quality.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.60-61
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• 2007

IAZO (indium aluminium zinc oxide) anode films were co-sputtered on glass substrate using a dual target DC magnetron sputtering system. For preparation of IATO films, at constant DC power of IZO (indium zinc oxide) target of 100 W, the DC power of AZO (Aluminum zinc oxide) target was varied from 0 to 100 W. To analyze electrical and optical properties of IAZO anode, Hall measurement examination and UV/V is spectrometer were performed, respectively. In addition, structure of IAZO anode film was examined by X-ray diffraction (XRD) method. Surface smoothness was investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). From co-sputtered IAZO anode, good conductivity($2.32{\times}10^{-4}{\Omega}.cm$) and high transparency(approximately 80%) in the visible range were obtained even at low temperature deposition. Finally, J-V-L characteristics of phosphorescent OLED with IAZO anode were studied by Keithley 2400 and compared with phosphorescent OLED with conventional ITO anode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.64-65
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• 2007

High-efficiency white organic light-emitting diodes (WOLEDs) were fabricated with two emissive layers and exciton blocking layer was sandwiched between two phosphorescent dyes which were, bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (Flrpic) as blue emission and a newly synthesized red phosphorescent material guest, Bis(5-benzoyl-2-phenylpyridinato-C,N)iridium(III) (acetylacetonate) ((Bzppy)2Ir(III)acac). This exciton blocking layer prevents a triple-triple energy transfer between the two phosphorescent emissive layers with balanced emission of blue and red. The white device showed the Commission Internationale d'Eclairage (CIEx,y) coordinates of (0.34, 0.40) at the maximum luminance of $24100\;cd/m^2$ and maximum luminous efficiency of 22.4 cd/A, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.428-429
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• 2006

In this thesis, verifies electrical-optical characteristics of phosphorescent materials. basic structure of fabricating devices is glass/ITO/$\alpha$-NPD($300{\AA}$)/CBP:Guest($300{\AA}$)/BCP($80{\AA}$)/$Alq_3(100{\AA})$/Al($1000{\AA}$). In efficiency, fabrication of organic light emitting diodes using $Ir(btp)_2acac$ phosphorescent material is external quantum efficiency 0.268% as doping concentration 3%. At CIE coordinates, phosphorescent material $Ir(btp)_2acac$ following materials moves high purity red color(x=0.6686, y=0.3243). The brightness shows $285cd/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.399-400
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• 2007

In this work, we have investigated the characteristics of the phosphorescent OLED and flexible OLED fabricated on IZTO/glass and IZTO/PET anode film grown by magnetron sputtering, respectively. Electrical and optical characteristics of amorphous IZTO/glass anode exhibited similar to commercial ITO anode even though it was deposited at room temperature. In addition, the amorphous IZTO anode showed higher work function than that of the commercial ITO anode after ozone treatment for 10 minutes. Furthermore, a phosphorescent OLED fabricated on amorphous IZTO anode film showed improved current-voltage-luminance characteristics, external quantum efficiency and power efficiency in contrast with phosphorescent OLED fabricated on commercial ITO anode film. This indicates that IZTO anode is promising alternative anode materials for anode in OLEDs and flexible OLEDs.

• Journal of the Korean Applied Science and Technology
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• v.19 no.2
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• pp.97-102
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• 2002

Recently, the phosphorescent organic light-emitting devices (OLEDs) have been extensively studied for their high internal quantum efficiency. In this study, we synthesised several phosphorescent metal complexes, and certified their composition using NMR. We also investigated the characteristics of the phosphorescent OLEDs with the green emitting phosphor, $Ir(ppy)_{3}$. The devices with a structure of indium-tin-oxide(ITO)/N,N'-diphenyl-N,N'-(3-methylphenyI}-1,1'-biphenyl-4,4'-diamine (TPD)/metal complex doped in host materials/2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline(BCP)/tris (8-hydroxyquinolinato) Aluminum($Alq_{3}$)/Li:Al/Al was fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of tris(2-phenylpyridine)iridium ($Ir(ppy)_{3}$), we fabricated several devices and investigated their characteristics.