• Title/Summary/Keyword: organic light emitting device

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Electroluminescent Properties of Anthracene Chromophore with Naphthylethenyl Substituents

  • Kim, Hong-Soo;Jeong, Noh-Hee
    • Journal of the Korean Applied Science and Technology
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    • v.21 no.1
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    • pp.24-30
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    • 2004
  • New electroluminescent materials based on anthracene chromophore with naphthylethenyl substituent, 9,10-bis($\alpha$-naphthylethenyl)anthracene (a-BNA), as well as four kinds of its derivatives were synthesized, and luminescent properties of these materials were investigated. Electrolumineecent(EL) emission band was discussed based on their substituent structure differences. It was found that the emission band strongly depends on the molecular structure of introduced substituent. It can be tuned from 557 nm to 591 nm by changing the substituent structures. On the other hand, the anthracene chromophore with bulky substituent possessed high melting point and they gave stable films through vacuum-sublimation. The double layer EL device of ITO/TPD/emission layer/Mg:Ag was employed, and exhibited efficient orange light originating from emitting materials. EL emission with a maximum luminance was observed in the b-BNA emitting material, : maximum luminance was about 8,060 cd $m^{-2}$ at an applied voltage of 10 V and current density of 680 $mA/cm^2$. In conclusion, the electroluminescent properties also showed good difference with their substituent structure.

Significant Improvements in White OLED Color Purity by Doping Ratio of $(POB)_{2}Ir(pic)$ ($(POB)_{2}Ir(pic)$의 doping 비율에 따른 White OLED의 색순도 향상에 관한 연구)

  • Kim, Dong-Eun;Kim, Byoung-Sang;Park, Jae-Chu;Chang, Jeong-Soo;Kwon, Young-Soo
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1373-1374
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    • 2007
  • We has been synthesized $(POB)_{2}Ir(pic)$ as a red emitting materials and evaluated in the organic light emitting diodes (OLED). The layer of $Alq_3$ doped with $(POB)_{2}Ir(pic)$ as emitters has been demonstrated. The structure of the device is ITO/ NPB (40 nm) / $Zn(HPB)_2$ (40 nm)/ $Alq_3$ : $(POB)_{2}Ir(pic)$ (30 nm) / LiF / Al. We varied the doped rate of $(POB)_{2}Ir(pic)$. The doped rate is 0.4 %, 0.6%, 0.8 and 1.2%, respectively. When the doped rate of the $Alq_3$:$ Ir(POB)_{2}(pic)$ was 0.6%, white emission is achieved. The Commission Internationale de l'Eclairage (CIE) coordinates of the white emission are (0.316, 0.331) at an applied voltage of 10.75V.

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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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Application of OLED as the Integrated Light source for the Portable Lab-On-a-Chip (휴대형 랩온어칩을 위한 집적화 광원으로의 OLED 적용)

  • Kim, Ju-Hwan;Shin, Kyeong-Sik;Kim, Young-Min;Kim, Yong-Kook;Yang, Yeun-Kyeong;Kim, Tae-Song;Kang, Ji-Yoon;Kim, Sang-Sig;Ju, Byeong-Kwon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.05a
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    • pp.193-197
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    • 2004
  • The organic light emitting diode (OLED) is proposed as the novel source in the microchip because it has ideal merits (various wavelengths, thin-film structure and overall emitting) for the integration. In this paper, we fabricated the finger-type pin photodiodes for fluorescence detection and the advanced microchip with OLED integrated pn the microchannel. The finger-type in the diode design extended the depletion region and reduced the internal resistance about 31.2% than rectangular-type. The photodiodes had a 100pA leakage current and a 8720 sensitivity $(I_{Light}/I_{Dark})$ at -1 V bias. The interference filter with 32 layers ($SiO_2$, $TiO_2$) was directly deposited on the photodiode. The OLED was fabricated on the ITO coated glass and was bonded with LOC. The application of thin-film OLED increased the excitation efficiency and simplified the integration process extremely. The prototype device of this application had a superior sensitivity of 100nM-LOD in the fluorescence detection.

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Temperature Analysis for the Point-Cell Source in the Vapor Deposition Process

  • Park, Jong-Wook;Kim, Sung-Cho;Hun Jung
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1680-1688
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    • 2004
  • The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

Characteristics of organic electroluminescent devices having buffer layers (Buffer층을 가진 유기 전기 발광 소자의 특성)

  • 이호식;고삼일;정택균;이원재;김태완;강도열
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.06a
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    • pp.399-402
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    • 1998
  • Electroluminescent(EL) devices based on organic thin films have attracted lots of interests in large-area light-emitting display. One of the problems of such device is a lifetime, where a degradation of the cell is possibly due to an organic layers thickness, morphology and interface with electrode. In this study, light-omitting organic electroluminescent devices were fabricated using Alq$_3$(8-hydroxyquinolinate aluminum) and TPD(N,N'-diphenyl-N,N'-bis(3-methylphenyl(1-1\`-biphenyl]-4,4'-diamine). Where Alq$_3$ is an electron-transport and emissive layer, TPD is a hole-transport layer. The cell structure is ITO/TPD/Alq$_3$/Al and the cell is fabricated by vacuum evaporation method. In a measurement of current-voltage characteristics, we obtained a turn-on voltage at about 9 V. We also investigated stability of the devices using buffer layer with blend of PEI (Poly ether imide) and TPD by varying mot ratios between ITO and Alq$_3$. In current-voltage characteristics measurement, we obtained the turn-on voltage at about 6 V and observed an anomalous behavior at 3∼4 V. And we used other buffer layer of PEDT(3,4-pyrazino-3',4'-ethylenedithio-2,2',5,5'-tetrathiafulvalenium) with ITO/PEDT/TPD/Alq$_3$Al structure. We observed a surface morphology by AFM(Atomic Force Microscopy), UV/visible absorption spectrum, and PL(Photoluminescence) spectrum. We obtained the UV/visible absorption peak at 358nm in TPD and at 359nm in Alq$_3$, and the PL peaks at 410nm in TPD and at 510nm in Alq$_3$. We also studied EL spectrum in the cell structure of ITO/(TPD+PEI)/Alq$_3$/Al.

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Ar/$O_3$ PLASMA TREATMENT OF ITO SUBSTRATES FOR IMPROVEMENT OF OLED DEVICE PERFORMANCE (OLED 소자로의 응용을 위한 ITO 전극의 Ar/$O_3$ 플라즈마 표면개질)

  • Lem, J.S.;Kim, H.G.;Kim, Y.W.;Kang, D.H.;Jung, M.Y.;Kim, B.S.;Shin, P.K.;Lee, D.C
    • Proceedings of the KIEE Conference
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    • 2004.07c
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    • pp.1570-1572
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    • 2004
  • OLED(organic light-emitting diode)소자에 사용되는 ITO(Indium-tin oxide)전극에 Ar/$O_3$ 플라즈마 표면처리 함으로써 ITO전극에 표면상태의 개선에 좋은 영향을 미치는 것으로 나타났다. 13.56MHZ RF 플라즈마 장치를 이용하여 Ar/$O_3$ 플라즈마 처리한 후 AFM(atomic force microscopy)측정을 통해 표면 morphologyjroughless를 분석하고, XPS(X-Ray Photoelectron Spectroscopy)분석을 통해 표면의 화학적 조성비 분석을 수행 하였다.

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Electroluminescent Properties of Organic Light-emitting Diodes Depending on the Thickness of CuPc Hole-injection Layer (정공 주입층 CuPc 두께 변화에 따른 유기 발광 소자의 발광 특성)

  • Lee, Jung-Bok;Kim, Kyung-Hwan;Kim, Tae-Wan;Lee, Won-Jae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.12
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    • pp.899-903
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    • 2013
  • We investigated the luminescence properties of $Alq_3$ in the device structure of ITO/CuPc/TPD/$Alq_3$/Al. The CuPc as a hole-injection material and TPD as hole-transport material. Emission properties were measured by varying a layer thickness of CuPc (0 nm to 50 nm), which is the hole-injection layer. As a result, it was found that the hole injection occurs smoothly when the layer thickness was 20 nm among the thicknesses from 0 nm to 50 nm.

Synthesis of Phenanthridine-Containing Conjugated Copolymer and OLED Device Properties

  • Park, Lee-Soon;Jeong, Young-Chul;Han, Yoon-Soo;Kim, Sang-Dae;Kwon, Young-Hwan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.588-591
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    • 2004
  • Polyazomethine type conjugated copolymers containing phenanthridine units, poly(PZ-PTI), were synthesized by Schiff-base reaction. This new conjugated copolymer exhibited improved solubility in common organic solvents due to the presence of alkyl side chains as well as phenanthridine groups. Double layer (ITO/poly(PZ-PTI)/$Alq_3$/Mg) light emitting diode (LED) exhibited enhanced EL emission and efficiency compared to that of single layer (ITO/poly(PZ-PTI)/Mg) LED. With increasing the thickness of $Alq_3$ layer in double layer (ITO/poly(PZ-PTI)/$Alq_3$/Mg) LED the emission peak gradually shifted to the single layer (ITO/$Alq_3$/Mg) LED, confirming good hole transporting behaviour of the synthesized conjugated copolymer.

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Study on recombination zone of blue phosphorescent OLED (청색인광 OLED의 재결합 영역에 관한 연구)

  • Kim, Tae-Yong;Moon, Dae-Gyu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.305-306
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    • 2009
  • In this study, we have invastigated the recombination zone in the blue phosphorescent organic light-emitting devices with various partially doped structures. The basic device structure of the blue PHOLED was anode / hole injection layer (HIL) / hole transport layer (HTL) / emittingvastigated the recombination zone in the blue layer (EML) / hole blocking layer (HBL) / electron transport layer (ETL) / electron injection layer (EIL) / cathode. After the preparation of the blue PHOLED, the current density (J) - voltage (V) - luminance (L) and current efficiency characteristics were measured.

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