• Title/Summary/Keyword: Alq$_3$

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Self-developed Efficiency Measurement System of Organic Light-Emitting Diodes (자체 개발한 유기 발광 소자의 효율 측정 시스템)

  • Han, Wone-Keun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.537-538
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    • 2005
  • A way of measuring an efficiency of organic light-emitting diodes are studied. The efficiency is obtained from the current-voltage-luminance characteristics of the devices. Basically, number of charge carriers are obtained from the current-voltage characteristics, and the number of photons are obtained from the current of Si-photodetector. The organic light-emitting diodes are assumed as a lambertian light source and a program is made for calculating the efficiency. A device structure of ITO/TPD/$Alq_3$/Al is manufactured using thermal-vapor evaporation. This device is set into a measuring system and measured the efficiency. The efficiencies are measured using the lab-made program and commercially available equipments. The obtained values are similar to each other within 10% uncertainty.

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A Study on the Characteristics of OLEDS Using a New Hole Injection Layer (새로운 정공주입층을 이용한 OLEDs의 특성에 관한 연구)

  • Shim, Hye-Yeon;Jeong, Ji-Hoon;Kim, Jun-Ho;Kim, Young-Kwan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.1046-1049
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    • 2004
  • The improvement in OLEDS performance is correlated with the surface chemical composition, hole injection and electron injection. In this study, a new hole injection material, HIL202(NPB derivatives), was synthesized and the devices with the structure of ITO/HIL202/NPB/$Alq_3$/Liq/Al were fabricated. The devices with a new hole injection material showed the improved current density, luminance and life time then the NPB or conventional hole injection material based OLEDs, due to the improved adhesion morphology between ITO surface and hole injection material.

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Energy Band Schemes of Organic Electroluminescence Devices Using Lanthanide Metal Complexes (란탄계 금속 착화합물을 이용한 유기 전기 발광 소자의 에너지 밴드 구조의 연구)

  • Pyo, S.W.;Lee, J.H.;Lee, H.S.;Lee, S.H.;Kim, Y.K.;Kim, J.S.
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1735-1737
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    • 1999
  • In this study, several lanthanide complexes such as Eu$(TTA)_3$(Phen). Tb$(ACAC)_3$(Cl-Phen) were synthesized and the white-light electroluminescence (EL) characteristics of their thin films were investigated. where the devices having structures of anode/TPD/Tb$(ACAC)_3$(Cl-Phen)/Eu$(TTA)_3$(Phen)/$Alq_3$ or $Bebq_2$/ cathode and the low work function metal alloy such as Li:Al was used as the electron injecting electrode (cathode). Details on the white-light-emitting characteristics of these device structures were explained by the energy band diagrams of various materials used in these structures, where the energy levels of new materials such as ionization potential (IP) and electron affinity (EA) were measured by cyclic voltametric method.

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Bright and Efficient Electrophosphorescence from Polymer Based LED

  • Xie, Zhiliang;Qiu, Chengfeng;Peng, Huajun;Chen, Haiying;Wong, Man;Tang, Ben Zhong;Kwok, Hoi Sing
    • 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 $cd/m^{2}$.

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Organic LED Current Driving ability Analysis of Pentacene TFT's (펜타센TFT의 유기 LED 구동 능력 분석)

  • Ryu, Gi-Seong;Byun, Hyun-Sook;Choe, Ki-Beom;Kim, Yong-Kyu;Song, Chung-Kum
    • Proceedings of the IEEK Conference
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    • 2004.06b
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    • pp.379-382
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    • 2004
  • In this paper we fabricated a test panel for AMOLED on glass and PET substrate. The test panel consisted of the various size of OTFTs and OLEDs and the current driving capability of OTFTs for OLEDs has been investigated. OTFTs were made of the inverted staggered structure and employed polyvinylphenol (PVP) as the gate insulator and pentacene thin film as the active layer. The OTFTs produced the filed effect mobility of $0.3 cm^2/V.sec$ and on/off current ratio of $10^5$. OLEDs consisted of TPD for HTL and Alq3 for EML with 35nm thick, generating green monochrome light. We found that OTFT with channel length of 70${\mu}m$ and channel width of over 3.5mm provided the sufficient current to OLED to generate the luminescence of $0.3Cd/m^2$.

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Fabrication of Test Panel for AMOLED driven by Pentacene TFTs

  • Ryu, Gi-Seong;Byun, Hyun-Sook;Xu, Yong-Xian;Choe, Ki-Beom;Song, Chung-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.1034-1037
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    • 2004
  • In this paper we fabricated a test panel for AMOLED on glass and PET substrate. The test panel consisted of the various size of OTFTs and OLEDs and the current driving capability of OTFTs for OLEDs has been investigated. OTFTs were made of the inverted staggered structure and employed polyvinylphenol (PVP) as the gate insulator and pentacene thin film as the active layer. The OTFTs produced the filed effect mobility of 0.3$cm^2$/V.sec and on/off current ratio of $10^5$. OLEDs consisted of TPD for HTL and Alq3 for EML with 35nm thick, generating green monochrome light. We found that OTFT with channel length of 70${\mu}m$and channel width of over 3.5mm provided the sufficient current to OLED to generate the luminescence of 0.3Cd/$m^2$.

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Photoluminescent and Electroluminescent Characteristics of Thin Films of Terbium Complex with Various Ligand Prepared by Vacuum Evaporation Method (진공 증착법에 의한 다양한 Terbium Complexes 박막의 광학적 및 전기적 특성 연구)

  • 표상우;이명호;이한성;김영관;김정수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.11a
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    • pp.315-318
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    • 1998
  • Organic light-emitting diodes(OLEDs) or electroluminescent devices have attracted much attention because of their possible application as large-area light-emitting displays. Their structure was based on employing a multilayer device structure containing an emitting layer and a carrier transporting layer of suitable organic materials. In this study, several Tb complexes such as Tb(ACAC)$_3$(Phen), Tb(ACAC)$_3$(Phen-Cl) and Tb(TPB)$_3$(Phen) were synthesized and the photoluminescence(PL) and electroluminescence (EL) characteristics of their thin films were investigated by fabricating the devices having a structure of anode/HTL/terbium-oomplex/ETL/cathode, where TPD was used as an hole transporting and Alq$_3$ and TAZ-Si were used as an electron transporting materials. It was found that the photoluminescence(PL) and electroluminescence(EL) characteristics of these terbium complexes were dependent upon the ligands coordinated to terbium metal. Details on the explanation of electrical transport phenomena of the structure with I-V characteristics of the OLEDs using the trapped-charge-limited current(TCLC) model will be discussed.

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Low-Molecular-Weight White Organic-Light-Emitting-Devices using Direct Color Mixing Method

  • Lee, Sung-Soo;Song, Tae-Joon;Ko, Myung-Soo;Cho, Sung-Min
    • Journal of Information Display
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    • v.3 no.2
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    • pp.6-12
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    • 2002
  • In order to achieve white emission from organic light emitting devices (OLEDs), five distinct structures were fabricated and tested. The white emission was obtained using two different color-emitting materials (yellow from rubrene-doped $Alq_3$ and blue from DPVBi) with or without a carrier-blocking layer. For enhancing the red emission, two types of devices with three-color emitting materials were fabricated. The white emission, close to the CIE coordinate of (0.3,0.3), was achieved by using two blocking layers as well that as without a blocking layer. This paper covers the subject of controlling the location of exciton recombination zone. It has been found that there is a trade-off in that the devices with three color emitting layers do not show as much luminescence efficiency compared to those with two color emitting layers, but rather, show distinct red emission in the resultant emission spectra. The highest power efficiency was measured to be 1.15lm/W at 2,000 $cd/m^2$ for a structure with two color-emitting layers.

Characteristics of OLED Lifetime by ITO/glass Substrate Pre-treatment and Cathode Deposition Methods (ITO/glass 기판 전처리와 음극 전극 증착방법에 따른 OLED 수명 특성)

  • Shin, Se-Jin;Jang, Ji-Geun;Kim, Min-Young
    • Journal of the Semiconductor & Display Technology
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    • v.7 no.2
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    • pp.59-62
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    • 2008
  • The Lifetime of OLEDs by ITO/glass substrates cleaning method and cathode deposition method were investigated in the fabrication of green light emitting OLEDs with $Alq_3$-C545T fluorescent system. In our experiments, the optimum cleaning method was obtained at last processing of boiling IPA(isopropyl alcohol). And the optimum deposition methode was obtained at 3 steps deposition rate of Al. The deposition rate of 3 steps progressed changing from $0.5\AA$/sec to $3\AA$/ sec. The green light emitting OLED with plasma treatment at 150W for 2 minutes showed the highest luminance and efficiency of 20000 cd/$m^2$ and 16 lm/W. On the contrary, the OLED device without plasma treatment showed much lower performance with the luminance and efficiency of 3500 cd/$m^2$ and 2 lm/W.

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OLEDs's Voltage-Current Characteristics with a Thickness Variation of Hole Transport Layer and Emission Layer (OLEDs의 정공 수송층 및 발광층의 두께 변화에 따른 전압-전류 특성)

  • Yang, Jae-Hoon;Lee, Young-Hwan;Kim, Weong-Jong;Kim, Tae-Wan;Hong, Jin-Woong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.74-75
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    • 2005
  • Organic Light Emitting Diodes are attractive as alternative display components because of their relative merits of being self-emitting, having large intrinsic viewing angle and fast switching speed. But because of their relatively short history of development, much remains to be studied in terms of their basic device physics and design, manufacturing techniques, stability and so on. We invested electrical properties of N, N-diphenyl-N, N bis (3-methyphenyl)-1, 1'-biphenyl-4, 4'-diamine and tris-8-hydroxyquinoline aluminum when their thickness were changed variedly from 3:7 to 7:3 of their thickness ratios. And we also studied their optimal thickness respectively.

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