• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.702-705
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• 2007

New heteroleptic tris-cyclometalated iridium complex, $Ir(ppy)_2(dpq-5CH_3)$, was prepared, where ppy and $dpq-5CH_3$ represent phenylpyridine and 2(5'-methyl)- 4-diphenylquinoline, respectively. The heteroleptic iridium complex shows high luminescence efficiency by the intramolecular energy transfer from the energy absorbing ppy ligands to the luminescent $dpq-5CH_3$ ligand leading to a decrease on quenching or energy deactivation.

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.984-987
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• 2003

The electrophosphorescent emission properties were investigated in polymer light-emitting diodes (PLEDs) based on a poly(9-vinylcarbazole) (PVK) doped with a green phosphorescent dye of fac-tris(2-phenylpyridine) iridium (III) [$Ir(ppy)_3$]. A green light peaked at 516 nm was emitted from devices with a configuration of ITO/PEDOT:PSS/PVK:$Ir(ppy)_{3}$/BCP/$Alq_{3}$/LiF/Al. The optimal doping concentration of $Ir(ppy)_{3}$ in PVK was found at 2% by weight, under which maximum current efficiency of 24.3 cd/A and peak external quantum efficiency of 6.8% were achieved at the high luminance of 4240 $cd/m^{2}$. The external quantum efficiency of 5% and current efficiency of 18 cd/A can be sustained even at the very high luminance of 35000 $cd/m^{2}$.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.473-473
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• 2012

유기발광소자는 낮은 구동전압, 빠른 응답속도, 넓은 시야각 등의 장점으로 소형 디스플레이에 사용되며 차세대 조명으로 관심을 받고 있다. 고효율의 유기발광소자를 제작하기 위해서 다양한 유기 인광물질 합성 및 연구가 진행되고 있으며, 다양한 호스트 물질을 사용하여 전자와 정공의 주입을 향상하여 고효율의 인광 유기발광소자를 제작하였다. 본 논문에서는 발광층에 N,N'-dicarbazolyl-3,5-benzene (mCP)와 1,3,5-tri(phenyl-2-benzimidazole)-benzene (TPBi)를 혼합 호스트로 사용하였으며 tris(2-phenylpyridine)iridium ($Ir(ppy)_3$)청색 인광물질을 도핑하여 고효율의 인광 유기발광소자를 제작하였다. 유기발광소자의 발광층에 단일 호스트와 혼합 호스트의 전기적 및 광학적 특성을 비교 분석하여 전자 및 정공 수송 메커니즘을 규명하였다. 혼합 호스트 TPBi의 lowest unoccupied molecular orbital (LUMO) 준위와 엑시톤 저지층 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)의 LUMO 준위와 비슷하여 전자의 주입을 향상시키는 역할을 하며, 다른 혼합 호스트 mCP는 highest occupied molecular orbital (HOMO)와 정공수송층 N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB)의 HOMO와 비슷하여 정공의 주입을 향상시키는 역할을 하여, $Ir(ppy)_3$에 전자와 정공의 주입이 향상되어 고 효율의 인광 유기발광소자를 제작할 수 있었다. 이와 같은 실험결과는 인광 유기발광소자의 호스트 물질에 따른 전하주입 메커니즘을 설명 하였으며 고효율의 인광 유기발광소자 제작에 도움을 줄 것이다.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.437-439
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• 2000

The internal quantum efficiency of EL devices using fluorescent organic materials is limited within 25% because of the triplet excitons which can hardly emit light. So there has been considerable interest in finding ways to obtain light emission from triplet excitons. One approach has been to add phosphorescent compounds to one of the layers in an EL device. Then triplet excitons can transfer to these phosphorescent molecules and emit light. In this study, multilayer organic light-emitting devices with phosphorescent emitter, tris (2-phenylpyridine)iridium ($Ir(ppy)_3$) were prepared. The device exhibited power luminous efficiency of 1.07 1m/W at the luminance of $61.6\;cd/m^2$ diriven at the voltage of 9 V and current density of $1.9mA/cm^2$. At the luminance of $100\;cd/m^2$, the luminous efficiency was obtained 1.05 lm/W with the voltage of 9.5 V and the corrent density of $2.8\;mA/cm^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.469-472
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• 2008

New iridium complexes with 2-(3',5'-bis-trifluoromethylphenyl)-4-metoxypyridine [$(CF_3)_2ppyOMe$] were synthesized and characterized for blue phosphorescent materials. It was found that $Ir[(CF_3)_2ppyOMe]_2$(acac) gives blue emission at 471 nm with strong luminescence efficiency. We discuss the role played by electron withdrawing substituents and also how the ancillary ligand influences the emission peak.

• Textile Coloration and Finishing
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• v.2 no.2
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• pp.7-13
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• 1990

The polyacrylonitrile (PAN)/polypyrrole (PPy) composite films have been prepaxed by exposing the PAN films containing oxidizing agent such as ferric chloride or cupric chloride to pyrrole vapor. The formation of PPy in PAN was confirmed by means of IR spectroscopy and scanning electron microscopy and the X-ray differaction study showed the amorphous structure of PPy. The breaking strength of PAN/PPy composite films was 3-5 times lower but the breaking elongation of them was 4-5 times higher than that of PAN film.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.465-468
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• 2008

New green light emitting phosphorescent devices with host structure of TCTA[4,4',4"-tris(N-carbazolyl)-triphenylamine]/$TCTA_{0.5}TPBi_{0.5}$/TPBI[1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene] were proposed and investigated according to the thickness combination of host layers and the doping level of $Ir(ppy)_3$[tris(2-phenylpyridine) iridium(III)].

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1042-1045
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• 2006

The electrical and optical properties of electrophosphorescent organic light-emitting diodes (OLEDs) with modified hole blocking layer (HBL) were investigated. Well-known 2,9-dimethyl-4,7- diphenyl-1,10-phenanthroline (BCP) HBL is mixed with electrophosphorescent host material (4,4'-N,N'- dicarbazole-biphenyl: CBP) or electrophosphorescent dopant material (fac-tris(2-phenylpyridine) iridium: $Ir(ppy)_3$) or both. The highest external quantum efficiency was obtained in the device with $BCP-CBP-Ir(ppy)_3$ mixed HBL and we attribute this result to the additional charge recombination in mixed-HBL.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.240-244
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• 2009

Simple and high efficiency green phosphorescent devices using an intermixed double host of 4, 4', 4"-tris(N-carbazolyl) triphenylamine [TCTA], 1, 3, 5-tris (N-phenylbenzimiazole-2-yl) benzene [TPBI], phosphorescent dye of tris(2-phenylpyridine)iridium(III) [$Ir(ppy)_3$], and selective doping in the TPBI region were fabricated, and their electro luminescent characteristics were evaluated. In the device fabrication, layers of $70{\AA}$-TCTA/$90{\AA}$-$TCTA_[0.5}TPBI_{0.5}$/$90{\AA}$-TPBI doped with $Ir(ppy)_3$ of 8% and an undoped layer of $50{\AA}$-TPBI were successively deposited to form an emission region, and SFC137 [proprietary electron transporting material] with three different thicknesses of $300{\AA}$, $500{\AA}$, and $700{\AA}$ were used as an electron transport layer. The device with $500{\AA}$-SFC137 showed the luminance of $48,300\;cd/m^2$ at an applied voltage of 10 V, and a maximum current efficiency of 57 cd/A under a luminance of $230\;cd/m^2$. The peak wavelength in the electroluminescent spectral and color coordinates on the Commission Internationale de I'Eclairage [CIE] chart were 512 nm and (0.31, 0.62), respectively.