• Title/Summary/Keyword: Alq3

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Organic Light-Emitting Diodes Fabricated from $Alq_3$ in Different Crystalline Polymorphs

  • Kaji, Hironori;Fukushima, Tatsuya
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.185-188
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    • 2008
  • We have analyzed the structures of $Alq_3$ in different polymorphs by solid-state NMR. On the basis of the results, OLEDs were fabricated from different polymorphs of $Alq_3$. The current efficiency of the device fabricated from the mixture of $\alpha$-, $\gamma$-, and $\delta-Alq_3$ powders was higher than that from $\alpha-Alq_3$.

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Electroluminescence of a red fluorescent dye doped in an $Alq_{3}$:rubrene Mixed Host

  • Kang, Hee-Young;kang, Gi-Wook;Lee, Chang-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.948-951
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    • 2003
  • The electroluminescence (EL) properties were studied in organic light-emitting diodes with a red fluorescent dye, 4- (dicyanomethylene)- 2- tert-butyl-6 (1,1,7,7-tetramethyljulolidyl-9-enyl)- 4H- pyran (DCJTB) doped into tris-(8-hydroxyquinoline)aluminum ($Alq_{3}$), rubrene and the mixed matrix of $Alq_3$ and rubrene. The device with DCJTB doped into the $Alq_{3}$:rubrene mixed host shows an efficient red emission from DCJTB with a negligible EL emission from $Alq_{3}$ and a lower EL onset voltage compared to the device with DCJTB doped into the $Alq_{3}$ only host. The quantum efficiency is almost temperature-independent for the device with the $Alq_3:rubrene$ mixed host. The results indicate that recombination of injected electrons and holes occurs on rubrene and subsequent energy transfer to DCJTB dominates in the device with the $Alq_{3}$:rubrene mixed host.

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Comparative Investigation on the Light Emitting Characteristics of OLED Devices with a Single Layer of Alq3 and a Double Layer of Rubrene/Alq3

  • Jeong, Geon-Su;Lee, Bung-Ju;Kim, Hui-Seong;;Sin, Baek-Gyun
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.246.2-246.2
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    • 2014
  • Green-light emitting OLED with single layer of Alq3 and orange-light emitting OLED with double layer of rubrene/Alq3 as EML were fabricated and characterized comparatively. The two OLED devices were based on an anode of ITO, HTL of TPD, and cathode of Al, respectively. The green light emitting OLED was then prepared with Alq3 as both ETL and EML, while the orange-light emitting OLED was prepared with rubrene deposited on Alq3. All the component layers of the OLED devices were deposited by a thermal evaporation technique in vacuum. Photoluminescence characteristics of the EML layers were investigated. Electrolumiscence characteristics of the OLED devices were comparatively investigated.

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Optical Characteristics and Electric Field Dependency of $Alq_3$ Thin Film (Alq3박막의 광학특성과 전계 의존성)

  • Lee, Cheong-Hak;Park, Dae-Hee
    • Proceedings of the KIEE Conference
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    • pp.1358-1360
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    • 1998
  • In this paper, organic thin film LED(light emitting diode) having ITO glass/$Alq_3$/Al structure using an $Alq_3$ was fabricated by the vacuum evaporation and the absorbance, wave length, 1-V characteristics were investigated. Electroluminescence of green and wavelength of 510[nm] were observed in this device. We observed absorbance form 320[nm] to 430[nm] and knew unstability of $Alq_3$ material as light emitting device.

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Light-emitting devices with polymer-organic heterostructure

  • Do, Lee-Mi;Hwang, Do-Hoon;Choi, Kang-Hoon;Lee, Hyang-Mok;Jung, Sang-Don;Zyung, Taehyoung
    • Journal of the Optical Society of Korea
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    • v.1 no.2
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    • pp.116-119
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    • 1997
  • Highly quantum efficient and multi-color emissible polymer light emitting devices have been realized utilizing poly (1-dodecyloxy-4-methyl-1, 3-phenylene)(2, 5"-terthienylene)(hereafter, mPTTh polymer) as an emitting layer and tris(8-hydroxyquinoline) aluminum (Alq3) as an electron transport layer. A single layer EL device of mPTTh polymer emits orange-colored light. EL efficiency increases as the thickness of Alq3 layer increases, but the emission color becomes visually broad when the Alq3 layer thickness is greater than 30nm since the relative peak intensity of green EL from Alq3 layer grows. EL color is changed from orange to greenish orange as the thickness of Alq3 layer grows. EL color is changed from orange to greenish orange as the thickness of Alq3 layer increases. EL efficiency of the double layer device was greatly enhanced by 3000 times compared with that of a single layer device. Alq3 layer in device acts as a hole blocking electron transporting layer and an emitting layer as a function of the thickness of Alq3 layer.ayer.

Sequential Formation of Multiple Gap States by Interfacial Reaction between Alq3 and Alkaline-earth Metal

  • Kim, Tae Gun;Kim, Jeong Won
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.129.2-129.2
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    • 2013
  • Electron injection enhancement at OLED (organic light-emitting diodes) cathode side has mostly been achieved by insertion of a low work function layer between metal electrode and emissive layer. We investigated the interfacial chemical reactions and electronic structures of alkaline-earth metal (Ca, Ba)/Alq3 [tris(8-hydroxyquinolinato)aluminium] and Ca/BaF2/Alq3 using in-situ X-ray & ultraviolet photoelectron spectroscopy. The alkaline-earth metal deposited on Alq3 generates two energetically separated gap states in sequential manner. This phenomenon is explained by step-by-step charge transfer from alkali-earth metal to the lowest unoccupied molecular orbital (LUMO) states of Alq3, forming new occupied states below Fermi level. The BaF2 interlayer initially prevents from direct contact between Alq3 and reactive Ca metal, but it is dissociated into Ba and CaF2. However, as the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with underlying Alq3. The influence of the multiple gap state formation by the interfacial chemical reaction on the OLED performance will be discussed.

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Impedance characteristics with various $Alq_3$ thickness in ITO/$Alq_3$/Al organic light-emitting diodes (ITO/$Alq_3$/Al의 유기 발광 소자에서 $Alq_3$의 두께 변화에 따른 임피던스 특성)

  • Gong, Doo-Won;Koo, Ja-Ryong;Kim, Young-Kwan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.477-478
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    • 2005
  • The devices with a structure of ITO/$Alq_3$/Al were fabricated and their impedance properties were analyzed. It is obtained that an effect of resistance $R_p$ of the device was dominant at the low frequency and the high voltage region, emitting region, and it is ignored at the high frequency region. Capacitance $C_p$ appears intensely in a range of all frequencies of non-emitting region, below turn on voltage.

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A Study on the Dielectric Polarization of $ITO/Alq_3/Al$ Structure Organic Light-emitting Diodes ($ITO/Alq_3/Al$ 구조 유기 발광 소자의 유전분극 현상의 연구)

  • Oh, Yong-Cheul;Shin, Cheol-Gi;Kim, Chung-Hyeak
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.1
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    • pp.73-77
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    • 2008
  • We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric polarization of organic light-emitting diodes using characteristics of impedance and equivalent circuit of $ITO/Alq_3/Al$. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of $1{\times}40Hz\;to\;1{\times}10^8Hz$. We obtained complex electrical conductivity, dielectric constant, and loss tangent(tan${\delta}$) of the device at room temperature. And, we obtained the equivalent circuit of $ITO/Alq_3/Al$ through analyzing dielectric constant and dielectric loss tangent. From these analyses, we could interpret a conduction mechanism and dielectric polarization.

Electronic Charge Transfer at the $Alq_3/Ba$ and $Alq_3/Au$ Interfaces by NEXAFS Spectroscopy

  • Lim, Jong-Tae;Yeom, Geun-Young
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1457-1460
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    • 2007
  • To understand the electronic charge transfer from cathode to an ETL in the TEOLED, the pristine $Alq_3$ thin film and the interfaces of both $Alq_3/Ba$ and $Alq_3/Au$ were investigated by using the NEXAFS spectroscopy. The unoccupied energy state of each interface using the NEXAFS Analyses at the C and OK-edges was assigned and charge transfer from Ba to ${\pi}^{\ast}$ of $Alq_3$ was investigated in detail.

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Impedance properties with thickness variation of $Alq_3$ in organic light-emitting diodes of ITO/$Alq_3$/Al (ITO/$Alq_3$/Al의 유기 발광 소자에서 $Alq_3$의 두께 변화에 따른 임피던스 특성)

  • Chung, Dong-Hoe;Kim, Sang-Keol;Chung, Taek-Gyun;Hur, Sung-Woo;Lee, Ho-Sik;Song, Min-Jong;Kim, Tae-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.1098-1101
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    • 2003
  • Complex impedances with frequency and voltage variation were analyzed in ITO/$Alq_3$/Al device structure at thickness 100 nm and 200 nm of $Alq_3$, respectively. At low frequency, complex impedance is mostly expressed by resistive component, and at the high frequency by capacitive component. Also, we have evaluated resistance, capacitance and permittivity.

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