• Title/Summary/Keyword: Alq$_3$

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Electrical Conduction Properties of OLED Device with Varying Temperature (온도 변화에 따른 OLED 소자의 전기전도 특성)

  • Lee, Ho-Shik;Kim, Gwi-Yeol;Park, Yong-Pil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.12
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    • pp.2361-2365
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    • 2007
  • Temperature-dependent current-voltage characteristics of Organic Light-Emitting Diodes(OLEDs) were studied. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3- methylrhenyi)-1,1'-diphenyl-4,4'-diamine (TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum(Alq3) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs was interpreted in terms of tunneling and trap-filled limited current.

The Microscopic Surface Properties of Rhodamine Derivatives in EL System (EL시스템의 Rhodamine 유도체화합물의 표면특성)

  • 박수길;조성렬;손원근;조병호;임기조;이주성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.04a
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    • pp.265-268
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    • 1997
  • Electroluminescent(EL) devices are constructed using multilayer organic thin film. A cell structure of glass substrate/Indium-Tinoxide/TPD as a hole transporting layer/Alq3+Rhodamine 101 perchrolate(Red3) as an emitting layer/Alq3 as an electrron transporting layer/Al as an electrode was employed. Optimal thickness of emitting layer in EL cell was performed from the viewpoint of the electronics properties of emitting layers. The general vapor-deposition method was used to control the thickness of omitting layer in EL devices and electro-optical characteristics were measured. It is clarified that controlling thickness of emitting layer in vapor-deposition film had an effect on the change of carrier injection and EL spectrum. The intensity of red omission with luminance of 81cd/$m^2$ was achived at 11V driving voltage. The surface morphology of emitting layer in EL devices was investigated.

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Enhanced efficiency of organic light-emitting diodes by doping the electrontransport layer

  • Lee, Hyun-Koo;Kwon, Do-Sung;Lee, Chang-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1410-1412
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    • 2005
  • We present that the electroluminescence (EL) efficiency can be improved by doping an electron transport layer (ETL) with organic materials which can make electron current increase. The electron transport layer of aluminum tris(8 -hydroxyquinoline) (Alq3) is doped with 2-(4-Biphenylyl)-5-(4-tertbutylphenyl)- 1,3,4-oxadiazole) (butyl-PBD) to enhance the electron mobility of the ETL. The higher quantum efficiency of device having ETL using Alq3 doped with butyl-PBD can be attributed to the improved electron and hole balance.

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Synthesis and Electroluminescent Properties of Diphenyl Benzeneamine Derivatives as Dopant Material

  • Seo, H.J.;Park, H.C.;Chung, T.G.;Lee, S.E.;Park, J.W.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.955-958
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    • 2003
  • We report the photo-(PL) and electroluminescence (EL) properties of new conjugated compounds based on diphenyl benzeneamine moiety, 4,4'-(1,4-phenylenedi-(1E)-2,1-ethenediyl]bis(N,N-diphenyl-benzenamine](PEDB) and 4,4'-([1,1 -biphenyl]-4,4'-diyldi-2,1-ethenediyl)bis[N,N-diphenyl-benzenamine)(BPEDB), as emitting materials and dopant materials. The ITO/m-MTDATA/NPB/DPVBi + BPEDB(1%) /Alq3/LiF/Al device shows blue EL spectrum at 458nm and high efficiency(5.3 cd/A). PEDB as dopant shows also blue EL spectrum around ${\lambda}$ max=463nm and 4.1 cd/A high efficiency in ITO/m-MTDATA/NPB/DPVBi + PEDB(1%)/Alq3/LiF/Al device.

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Synthesis and Electroluminescent Properties of Imidazole Derivatives (Imidazole 유도체들의 합성과 유기 발광 특성 연구)

  • 박종욱;서현진
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.12
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    • pp.1121-1124
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    • 2003
  • We report the photo (PL) and electro luminescence (EL) properties of new conjugated compounds based on imidazole moiety, 4,4' -di(4,5 diphenyl-N-imidazolyl)stilbene(DDPIS) and 4,4'-di(2,4,5-triphenyl-N-imidazolyl)stilbene(DTPIS), as emitting materials. ITO/m-MTDATA/NPB/DDPIS/Alq3/LiF/AI device shows blue EL spectrum at 456 ㎚ and 0.3 cd/ A and turn on voltage at 7 ∼ 8 V. DTPIS shows blue EL spectrum at around λmax=453㎚ and 0.5 cd/A efficiency in ITO/m-MTDATA/NPB/DTPIS/Alq3/LiF/Al device.

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.

Effects of PEDOT:PSS Buffer Layer in a Device Structure of ITO/PEDOT:PSS/TPD/Alq3/Cathode

  • Ahn, Joon-Ho;Lee, Joon-Ung
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.1
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    • pp.25-28
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    • 2005
  • We have investigated the effects of hole-injection buffer layer in organic light-emitting diodes using poly(3,4-ethylenedioxythiophene):poly(stylenesulfonate)(PEDOT:PSS) in a device structure of $ITO/PEDOT:PSS/TPD/Alq_{3}/cathode$. Polymer PEDOT:PSS buffer layer was made by spin casting method. Current-voltage, luminance-voltage characteristics and efficiency of device were measured at room temperature with a variation of cathode materials; Al, LiF/Al, LiAl, and Ca/Al. The device with LiF/Al cathode shows an improvement of external quantum efficiency approximately by a factor of ten compared to that of Al cathode only device. Our observation shows that cathode is important in improving the efficiency of the organic light-emitting diodes.

Preparation and Characteristics of Organic Electroluminescence Devices using Multilayer Structure with Carrier Transport Materials (다층막 구조를 이용한 유기 EL소자의 제작과 특성에 관한 연구)

  • Lee, Sang-Youn;Kim, Young-Kwan;Kim, Jung-Soo
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1563-1565
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    • 1997
  • Electroluminescence(EL)devices based on organic thin layers have attracted lot of interests because of their possible application as large-area light-emitting display. One of the problems of such devices is lifetime of the cell, where the degradation of the cell is partially due to the crystalliyzation of organic layers. In large part, this problem can be solved by using a multilayer device structure prepared by vapor deposition technique. In this study, blue lightemitting multilayer organic electroluminescence devices were fabricated using Poly (9-vinyl-carbazole) (PVK) and 2-(4'-tert-butylpheny])-5-(4"-bis-phenyl)1,3,4-oxadiazole (PBD) as hole trasport and electron transport material, respectively, where tris(8-hydroxyquinolinate) aluminum (Alq3) was used as a luminescenct material. A cell structure of glass substrate/indume-tin-oxide(ITO)/PVK/$Alq_3$/PBD/Mg:In was employed.

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Efficiency Improvement of the Organic Light-Emitting Diodes depending on Thickness Variation of Hole-Infection Materials (정공 주입 물질 두께 변화에 따른 유기 발광 다이오우드 효율 향상)

  • Kim, Weon-Jong;Lee, Young-Hwan;Cha, Ki-Ho;Lee, Sang-Kyo;Kim, Tae-Wan;Hong, Jin-Woong
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1291-1292
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    • 2006
  • In the structure of ITO/HIL/$Alq_3$/Al device, we investigated an efficiency improvement of the Organic Light-Emitting Diodes depending on thickness variation of hole-injection layer. Using the thermal evaporation in a base vacuum $5{\times}10^{-5}$[Torr], we have measured efficiency after the $Alq_3$ was evaporated to 100 [nm] as a deposition rate $1.5[{\AA}/s]$. In optimal condition, when PTFE thickness increased from 0 to 3.0 [nm], we have obtained that an optimal thickness of PTFE was 2.5 [nm]. And using the PTFE, luminance efficiency and external quantum efficiency of the device were improved by 12.8 times and 11.1 times, respectively.

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The Luminescent Properties of Red OLED Devices Doped with Two Dopants (2원 첨가 적색 OLED 소자의 발광특성)

  • Kim, Kyong-Min;Ju, Sung-Hoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.6
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    • pp.531-535
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    • 2007
  • To invest the luminescent characteristics of red light emitting OLED device, a dual dopant system was incorporated into the emitting layer. The multiple layer OLED device structure was $ITO(1500\;{\AA})/HIL(200\;{\AA})/a-NPD(600\;{\AA})/EML(300\;{\AA})/Alq_3(200\;{\AA})/LiF(7\;{\AA})/Al(1800\;{\AA})$. The concentrations of the rubrene dopant were tested at 0 vol.%, 3 vol.%, 6 vol.% and 9 vol.%. The maximum device efficiency and life time were obtained at the rubrene dopant concentration of 6 vol.%. Emission spectrum and color coordinate of devices showed no relationship with rubrene dopant concentration. Experiment results show that rubrene dopant absorbs energy from $Alq_3$ host and transfer it to RD1 dopant acting as an energy intermediate and influencing the device efficiency, finally the red light is emitted from the RD1 dopant.