• Title/Summary/Keyword: phosphorescence

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Characteristics of blue phosphorescent OLED with PVK host layer. (PVK Host를 이용한 청색인광 OLED의 특성)

  • Lee, Sun-Hee;Jo, Min-Ji;Moon, Dae-Gyu
    • 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.

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Effects of Electron Transport Layers on Electrical and Optical Characteristics of Blue Phosphorescent Organic Light Emitting Diodes (전자수송층이 청색 인광 OLED의 전기 및 광학적 특성에 미치는 영향)

  • Suh, Won-Gyu;Moon, Dae-Gyu
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.4
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    • pp.323-326
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    • 2009
  • We have developed blue-emitting phosphorescent organic light emitting diodes (OLEDs) using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tris (8-quinolinolato)aluminum ($Alq_3$) electron transport layers. As blue dopant and host materials, bis[(4,6-di-fluorophenyl)-pyridinate-N,C2']picolinate (FIrpic) and N,N'-dicarbazolyl-3,5-benzene (mCP) were used, respectively. The driving voltage, current efficiency and emission characteristics of devices were investigated. While the driving voltage was about $1{\sim}2$ V lower in the device with an $Alq_3$ layer, the current efficiency was about 66 % higher in the device with BCP electron transport layer. the blue phosphorescent OLED with BCP layer exhibited higher purity of color, resulting from a relatively weak electroluminescence intensity at 500 nm.

SiO2/ZnS:Cu/ZnS Triplex Layer Coatings for Phosphorescence Enhancement

  • Zhang, Wen-Tao;Lee, Hong-Ro
    • Journal of the Korean institute of surface engineering
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    • v.41 no.4
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    • pp.169-173
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    • 2008
  • The objective of this study is to coat the $SiO_2$ layer uniformly on the ZnS:Cu phosphors by using Sol-Gel method. From results of SEM micrographs observation, XRD and XPS analysis, it could be confirmed that $SiO_2$ layer was relatively well coated on ZnS:Cu particles. $Ag_2S$ was used as a decoding chemical to analyze the dense and uniform coating performance of $SiO_2$ layer on phosphor particles. It could be concluded that phosphors synthesized from our two step replacement method showed strong blue peak comparing to other method and rather weak green peak also. Obtained particle size of phosphors were about 20m diameter. Luminescence properties of the phosphors were examined by photoluminescence spectra at the excitation wavelength of 270 nm.

Eu Doping Effect on $CaAl_2O_4:Eu^{2+}$ Phosphor Material

  • Bartwal, Kunwar Singh;Ryu, Ho-Jin
    • Journal of the Semiconductor & Display Technology
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    • v.6 no.2 s.19
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    • pp.65-68
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    • 2007
  • High brightness and long persistent luminescence phosphor $CaAl_2O_4:Eu^{2+}$ was prepared with varying $Eu^{2+}$ concentration by solid state reaction technique. Synthesized materials were investigated by powder X-ray diffractometer (XRD), SEM, TEM, photoluminescence excitation and emission spectra. Broad band UV excited luminescence of the $CaAl_2O_4:Eu^{2+}$ was observed in the blue region (${\lambda}_{max}\;=\;440\;nm$) due to transitions from the $4f^65d^1$ to the $4f^7$ configuration of the $Eu^{2+}$ ion. The decay time of the persistence indicated that the persistent luminescence phosphor has bright phosphorescence and maintains a long duration. These materials have great potential for outdoor night time displays.

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Novel Small Molecular Materials For Solution Green Phosphorescent OLEDs

  • Lee, Ho-Jae;Yu, Eun-Sun;Jung, Sung-Hyun;Kim, Hyung-Sun;Kang, Eui-Su;Chae, Mi-Young;Chang, Tu-Won
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.791-793
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    • 2009
  • We have developed novel small molecular materials for solution phosphorescent OLEDs having multilayered device structures. These novel materials are applied as an interlayer which is between a buffer layer (or hole injection layer) and an emitting layer to improve the luminance efficiency of solution green phosphorescent OLEDs. In order to form stable double layers by spincoating process, we take the advantage of solubility differences of interlayer materials and emitting materials. Using CIM3 as an interlayer, we have attained the best luminance efficiency, 36 cd/A at a given constant of 2000cd/$m^2$ in the structure of ITO/PEDOT:PSS/CIM3/CIM6:Ir(mppy)$_3$/BAlq/Alq$_3$/LiF/Al.

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A Simple Structural Red Phosphorescent Organic Light-Emitting diodes with high-efficiency and low-voltage

  • Seo, Ji-Hyun;Jin, You-Young;Kim, Hoe-Min;Choi, Eun-Young;Kim, Jun-Ho;Lee, Kum-Hee;Yoon, Seung-Soo;Kim, Young-Kwan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.46-48
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    • 2009
  • We demonstrated that the simple layered red phosphorescent organic light-emitting diodes are possible to have high efficiency and low driving voltage without hole injection and transport layers. The simplified OLED shows the max. current efficiency, power efficiency and quantum efficiency of 26.3 cd/A, 20.7 lm/W and 16.7 %, respectively.

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Novel Bipolar Host Materials for Phosphorescent OLEDs

  • Yu, Eun-Sun;Kim, Nam-Soo;Kim, Young-Hoon;Chae, Mi-Young;Chang, Tu-Won
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.636-639
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    • 2007
  • We have developed novel bipolar host materials, designed to have both electron transporting and hole transporting abilities, which show significant increase in luminance efficiency and decrease in driving voltage of green phosphorescent OLEDs. In case of the best host material, CheilGH-3, the driving voltage was decreased 27 % at a given constant luminance of $1000cd/m^2$. Also the luminance efficiency was enhanced 44 % and the power efficiency was almost doubled compared to the reference device using CBP as a host.

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Highly Efficient Red Phosphorescent OLEDs Employing a Multifunctional Oligofluorene Host

  • Tsai, Ming-Han;Su, Hai-Ching;Wu, Chung-Chih;Wong, Ken-Tsung;Li, Wen-Ren
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.663-666
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    • 2007
  • High-efficiency red phosphorescent OLEDs employing a novel red emitter and a multifunctional oligofluorene host are reported. With qazIr(acac) as the red phosphorescent dopant, a maximum external quantum efficiency of 19% and maximum power efficiency of 11 lm/W are achieved. In addition, single layer devices using such host and dopant materials have efficiencies up to 13%.

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Analysis of Low Power Consumption AMOLED Displays on Flexible Stainless Steel Substrates

  • Hack, Mike;Hewitt, Richard;Ma, Ray;Brown, Julie J.;Choi, Jae-Won;Cheon, Jun-Hyuk;Kim, Se-Hwan;Jang, Jin
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.58-61
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    • 2007
  • We present simulations and results to demonstrate the viability of stainless steel foil as a substrate for low power consumption, flexible AMOLED displays. Using organic planarization layers, we achieve very smooth surface properties, resulting in excellent TFT performance, that can be repetitively flexed without significantly affecting device performance. The use of phosphorescent OLEDs enables the design of low power consumption 40" AMOLED displays.

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Phosphorescent Iridium Complexes for OLEDs Based on 1-Phenylpyrazole Ligands with Fluorine and Methyl Moieties

  • Yoon, Seung Soo;Song, Ji Young;Na, Eun Jae;Lee, Kum Hee;Kim, Seong Kyu;Lim, Dong Whan;Lee, Seok Jae;Kim, Young Kwan
    • Bulletin of the Korean Chemical Society
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    • v.34 no.5
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    • pp.1366-1370
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    • 2013
  • A series of phosphorescent iridium(III) complexes 1-4 based on phenylpyrazole were synthesized and their photophysical properties were investigated. To evaluate their electroluminescent properties, OLED devices with the structure of ITO/NPB/mCP: 8% Iridium complexes (1-4)/TPBi/Liq/Al were fabricated. Among those, the device with 3 showed the most efficient white emission with maximum luminance of 100.6 $cd/m^2$ at 15 V, maximum luminous efficiency of 1.52 cd/A, power efficiency of 0.71 lm/W, external quantum efficiency of 0.59%, and CIE coordinates of (0.35, 0.40) at 15.0 V, respectively.