• Environmental Analysis Health and Toxicology
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• 제11권1_2호
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• pp.49-57
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• 1996

The production of reactive oxygen species on addition of hexavalent chromium (potassium dichromate, $K_2Cr_2O_7$ ) to lung cells in culture was studied using flow cytometer analysis. A Coulter Epics Profile flow cytometer was used to detect the formation of reactive oxygen species after $K_2Cr_2O_7$ was added to A549 cells grown to confluence. The cells were loaded with the dye, 2',7'-dichlorofluorescein diacetate, after which cellular esterases removed the acetate groups and the dye was trapped intracellularly. Reactive oxygen species oxidized the dye, with resultant fluorescence. Increased doses of Cr(VI) caused increasing fluorescence (10-fold higher than background at 200 gM). Addition of Cr(III) compounds, as the picolinate or chloride, caused no increased fluorescence. Electron paramagnetic resonance (EPR) spectroscopic studies indicated that three (as yet unidentified) spectral "signals" of the free radical type were formed on addition of 20, 50, 100 and 200 gM Cr(VI) to the A549 cells in suspension. Two other EPR 'signals" with the characteristics of Cr(V) entities were seen at field values lower than the standard free radical value. radical value.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.415-417
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• 2009

Color stable and efficient two wavelength white organic light emitting diodes (OLEDs) were fabricated using a iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,$C^2$'] picolinate (FIrpic) as a blue phosphorescent emitter and a bis(1-phenylisoquinolinato-$C^2$,N)iridium (acetylacetonate) ((piq)$_2$Ir(acac)) as a red phosphorescent emitter. The emitting layers consist of two blue emitting layers and one red emitting layer which is between the two blue layers. The device reaches the peak efficiencies of 7.84 % and 10.3 cd/A at 0.6 mA/$cm^2$. Furthermore, there was little change of EL spectra according to current density change in the device.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.184-187
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• 2009

In this paper, we study effect of charge balance on performance of blue phosphorescent organic light emitting diodes (OLEDs). Charge balance determines the location of recombination zone in the OLEDs. By tuning the charge balance in iridium (III) bis[(4,6-difluorophenyl)-pyridinate-N,C2']picolinate (FIrpic) based blue phosphorescent organic light-emitting devices (PHOLEDs) with a high mobility and high triplet energy electron transporting material, we were able to achieve a high current efficiency of 60 cd/A which is a 3X improvement over previous devices with 3,5'-N,N'-dicarbazole-benzene (mCP) host.

• 한국전기전자재료학회논문지
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• 제23권2호
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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/$m^2$.

• 한국전기전자재료학회논문지
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• 제22권6호
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• pp.512-515
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• 2009

We have fabricated blue phosphorescent organic light emitting diodes (PHOLEDs) using a 3,5'-N,N'-dicarbazole-benzene (mCP) host and iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,$C^{2'}$] picolinate (Flrpic) guest materials, The Flrpic was partially doped into the mCP host layer, for investigating recombination zone, current efficiency, and emission characteristics of the blue PHOLEDs. The recombination of electrons and holes takes place inside the mCP layer adjacent to the mCP/hole blocking layer interface. The best current efficiency was obtained in a device with an emission layer structure of mCP (10 nm)/mCP:Flrpic (20 nm, 10%). The high current efficiency in this device was attributed to the confinement of Ffrpic triplet excitons by the undoped mCP layer with high triplet energy, which blocks diffusion of Ffrpic excitons to the adjacent hole transport layer with a lower triplet energy.

• Journal of Animal Science and Technology
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• 제44권4호
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• pp.419-426
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• 2002

본 시험은 성장단계별로 서로 다른 수준의 CrP를 첨가하여 성장성적, 혈액성상 및 도체품질에 미치는 영향을 규명하고자 실시하였다. 시험Ⅰ에서 일당증체, 일당건물섭취량 및 사료효율에는 유의적인 차이가 없었다(p>0.05). 혈액성상에서 혈장 Glucose와 PUN의 농도에는 영향이 없었지만 혈중 인슐린의 농도는 0.05% CrP첨가구가 대조구의 2배되는 1.47ng/ml 인데 반하여 혈중 NEFA의 농도는 59.00 mEq/dl 로 유의적으로 낮게 나타났다(p<0.05). 이는 인슐린의 농도의 증가 및 인슐린의 활성의 증가로 인하여 지방합성대사가 활발히 진행된 결과로 사료된다. 이러한 결과를 도체분석결과가 뒤받침 해주고 있는데 비록 통계적인 유의차는 없지만 0.05% CrP 첨가구의 등지방두께가 대조구에 비해 22.33% 높은 3.67cm로 나타났다. 시험Ⅱ에서 비록 일당증체, 일당건물섭취량 및 사료효율에는 유의적인 차이가 없었지만(p>0.05), 첨가초기 즉 0.05% CrP 첨가구에서는 첫 60일간, 0.025% CrP 첨가구에서는 첫 120일간 대조구보다 우수한 성적을 나타냈다. 혈장 Glucose와 PUN의 농도에는 영향이 없었다. 통계적인 유의차는 없었지만 혈 중 인슐린의 농도는 0.025% CrP 첨가구는 대조구보다 8.88% 높은 1.35ng/ml로 나타났고 0.05% CrP 첨가구는 오히려 1.13ng/ml로 대조구보다 낮게 나타났다. NEFA의 농도는 시험Ⅰ에서와 같은 차이는 없었지만 CrP 첨가수준이 증가할수록 감소하는 추세를 나타냈고 등지방두께는 일정한 변화추세를 보이지 않았다.

• Transactions on Electrical and Electronic Materials
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• 제12권2호
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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.

• 한국전기전자재료학회논문지
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• 제27권4호
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• pp.232-237
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• 2014

We have fabricated white organic light-emitting diodes (OLEDs) by co-doping of red and blue phosphorescent guest emitters into the single host layer. Tris(2-phenyl-1-quinoline) iridium(III) [$Ir(phq)_3$] and iridium(III)bis[(4,6-di-fluorophenyl)-pyridinato-$N,C^{2^{\prime}}$]picolinate (FIrpic) were used as red and blue dopants, respectively. The effects of dopant concentration on the emission, carrier conduction and external quantum efficiency characteristics of the devices were investigated. The emissions on the guest emitters were attributed to the energy transfer to the guest emitters and direct excitation by trapping of the carriers on the guest molecules. The white OLED with 5% FIrpic and 2% $Ir(phq)_3$ exhibited a maximum external quantum efficiency of 19.9% and a maximum current efficiency of 45.2 cd/A.

• 한국전기전자재료학회논문지
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• 제27권6호
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• pp.377-382
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• 2014

We have investigated the effects of spacer layer inserted between blue and red doped emission layers on the emission and efficiency characteristics of phosphorescent OLEDs. N,N'-di-carbazolyl-3,5-benzene (mCP) was used as a host layer. Iridium(III)bis[(4,6-di-fluorophenyl)- pyridinato-N,$C^2$']picolinate (FIrpic) and tris(1-phenyl-isoquinolinato-$C^2$,N)iridium(III) [Ir(piq)3] were used as blue and red dopants, respectively. The emission layer structure was mCP (1-x) nm/mCP:$Ir(piq)_3$ (5 nm, 10%)/mCP (x nm)/mCP:FIrpic (5 nm, 10%). The thickness of mCP spacer layer was varied from 0 to 15 nm. The emission from $Ir(piq)_3$ and the efficiency of the device were dominated by energy transfer from mCP host and FIrpic molecules, and by diffusion of mCP host triplet excitons.

• ETRI Journal
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• 제38권2호
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• pp.260-264
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• 2016

We report on highly efficient blue, orange, and white phosphorescent organic light-emitting diodes consisting only two organic layers. Hole transporting 4, 4,' 4"-tris (N-carbazolyl)triphenylamine (TcTa) and electron transporting 2-(diphenylphosphoryl) spirofluorene (SPPO1) are used as an emitting host for orange light-emitting bis(3-benzothiazol-2-yl-9-ethyl-9H-carbazolato) (acetoacetonate) iridium ((btc)2(acac)Ir) and blue light-emitting iridium(III)bis(4,6-difluorophenyl-pyridinato-N,C2') picolinate (FIrpic) dopant, respectively. Combining these two orange and blue light-emitting layers, we successfully demonstrate highly efficient white PHOLEDs while maintaining Commission internationale de l'eclairage coordinates of (x = 0.373, y = 0.443). Accordingly, we achieve a maximum external quantum, current, and power efficiencies of 12.9%, 30.3 cd/A, and 30.0 lm/W without out-coupling enhancement.