• Title/Summary/Keyword: Organic EL

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Electroluminescence Properties from Blend films of poly(3-hexylthiophene) and poly(N-vinylcarvazole) (P3HT와 PVK 블렌드 막에서의 전계 발광 특성)

  • Kim, Dae-Jung;Kim, Shang-Gi;Gu, Hal-Bon;Jung, Un-Jo;Park, Ge-Chun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.972-975
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    • 2002
  • Electroluminescence(EL) devices based on organic thin layers have attracted lot of interests because of their application as display. One of the problems is red material. It offered a short life and poor emission efficiency to boot. In this study, this problem can be solved by using a multi-layer device structure. Organic electroluminescent devices which are composed of organic thin multi-layer films are fabricated. The basic structure is ITO / Emitting layer / LiP / Al EL device in which Hole transport/Electron blocking PVK layer was blending. We demonstrate the enhancement of eletroluminescence (EL) from blends of poly(3-hexylthiophene) in poly(N-vinylcarvazole). The emitting layer is consisted of a host material(PVK) and a guest emitting material(P3HT). It was showed higher EL intensity and their electro-optical properties were investigated.

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Emission Properties of White Light Emission Organic Electroluminescent Device using Exciplex Emission (Exciplex를 이용한 백색 유기 전계발광소자의 발광특성)

  • 김주승;김종욱;구할본
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.9
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    • pp.762-767
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    • 2001
  • We report the white light emission from the multilayer organic electroluminescent(EL) device using exciplex emission. The exciplex at 500nm originated between poly(N-vinylcarvazole)(PVK) and 2,5-bis(5'-tert-butyl-2-benzoxazoly)thiophene(BBOT) and exciplex of 50nm originated from N,N'-diphenyl-N,N'-(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD) and BBOT were observed. Also, the energy transfer from PVK to BBOT and poly(3-hexylthiophene)(P3HT) in mixed emitting materials was occurred. The electroluminescence(EL) spectra of organic EL device which have a device structure of ITO/CuPc(5nm)/emitting layer(100nm)/BBOT(30nm)/LiF(1.4nm)/Al(200nm) were slightly changed as a function of the applied voltage. The luminance fo 12.3 ${\mu}$W/$\textrm{cm}^2$ was achieved at 20V and EL spectrum measured at 20V corresponds to Commission Internationale de L\`Eclairage(CIE) coordinates of x=0.29 and y=0.353.

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A Study on the Enhancement of Emission Efficiency of an Organic EL Devices Using the RF Plasma (RF 플라즈마를 이용한 유기 EL소자의 발광 효율에 관한 연구)

  • 박상무;김형권;신백균;임경범;이덕출
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.9
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    • pp.400-406
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    • 2003
  • Efficient electrodes are devised for organic luminescent device(OLED). ITO electrode is treated with $O_2$ plasma. In order to inject hole efficiently, there is proposed the shape of anode that inserted plasma polymerized films as buffer layer between anode and organic layer using thiophene monomer. In the case of device inserted the buffer layer by using the plasma polymerization after $O_2$ plasma processing for ITO transparent electrode, since it forms the stable interface and reduce the moving speed of hole, the recombination of hole and electronic are made in the emitting layer. Therefore it realized the device capability of two times in the aspect of luminous efficiency than the device which do not be inserted the buffer layer. Experiments are limited to the device that has the structure of TPD/$AIq_3$, however, the aforementioned electrodes can similarly applied to the organic luminous device and the Polymer luminous device.

A Study on Organic Multithin Layer EL Devices (다층 유기 초박막 EL소자에 관한 연구)

  • Cho, S.R.;Kim, J.J.;Park, J.E.;Son, W.K.;Lim, K.J.;Park, S.G.;Lee, J.S.
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1516-1518
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    • 1997
  • Recently lots of study on EL have been performed by other researcher. Organic multilayer system of TPD/$Alq3$ and Rhodamine 101 perchrolate/Alq3/ was constructed on ITO and finally Al as cathodic electrode. The thickness of emitting layer was $150{\AA}$ and device was fabricated by changing amount of dopant. AFM image for each surface morphology and EL spectra using fluoromax-2 was investigated. Electrical and emission properties of EL device was dependent on deposition method and condition.

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Luminance Characteristics of a Novel Red-Light-Emitting Device Based on Znq2 and Dye

  • Cho, min-Jeong;Park, Wan-Ji;Lee, Jeong-Gu;Lim, In-Su;Lim, Kee-Joe;Kim, Hyun-Hoo
    • Transactions on Electrical and Electronic Materials
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    • v.3 no.2
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    • pp.16-19
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    • 2002
  • In this study, a novel red emitting organic electroluminescent (EL) device was fabricated with the bis(8-oxyquinolino)zinc II (Znq2) doped dye as an emitting layer. The Znq2 was synthesized successfully from zinc chloride (ZnC1$_2$) as an initial material. Then, we fabricated the red organic EL device with a dye (DCJTB) doped and inserted Znq2 between emission layer and cathode for increasing EL efficiency. The hole transporting layer is a N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-1,1'-diphenyl-4,4-diamine (TPD), and the host material of emission layer is Znq2. And the electrical and luminance characteristics of the device were measured. We found that the EL device with Znq2 inserting layer results in the increasing luminance efficiency.

Light Emitting Characteristics of Multi-layer OLEO Fabricated with DCM (DCM 계열을 이용한 OLED의 전기적인 발광 특성에 관한 연구)

  • Chun, Min-Ho;Yun, Suk-Won;Lim, Sung-Tack;Shin, Dong-Myung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.04b
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    • pp.57-60
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    • 2002
  • In generally, the guest-emitter doped system has been reported to give a bright electroluminescence(EL). The purpose of using doped system is to improve for increasing lifetime and efficiency, and tuning multicolor light. This indicates an enhanced electron-hole recombination rate in emitting layer. The purpose of this study is to obtain the high performance EL devices for flat panel display with red emission. We fabricated EL devices using the guest-host system. where DCM derivatives were taken as a dopant. The devices are fabricated in multilayer system with various concentration of the dopant (red light emitting dye). We measured the I-V characteristics and EL spectra from these devices. and we compared with photoluminescence(PL) quantum yield among the DCM derivatives. The emission mechanism of devices is participated in energy transfer. The energy transfer from these hosts to DCM generates luminescence spectra that vary from yellow red to red, depending on DCM derivatives. Absorption and emission spectra of organic materials composing the devices depend on the emission materials doped with the DCM derivatives. We demonstrated that the high EL efficiency can be achieved by doping host material with DCM derivatives and molecular steric structures

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Energy Transfer Phenomenon in Organic EL Devices Having Single Emitting Layer (단층형 유기 EL 소자의 에너지 전달 특성에 관한 연구)

  • Kim, Ju-Seung;Seo, Bu-Wan;Gu, Hal-Bon;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.331-334
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    • 2000
  • The organic electroluminescent(EL) device has gathered much interest because of its large potential in materials and simple device fabrication. We fabricated EL devices which have a blended single emitting layer containg poly(Nvinylcarbazole)[PVK] and poly(3-dodecylthiophene)[P3DoDT]. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer between polymer emitting layer and AI electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. Within the molar ratio 1:0, 2:1 and 1:1, the energy transfer was not saturated, which results in the not appearance of PVK emission in the blue region. In the voltage-current and voltage-light power characteristics of devices applied LiF layer, current and light power drastically increased with increasing with applied voltage. In the consequence of the result, the light power of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V.

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Organic Electroluminescence using Hyperbranched Poly(Phenylene Vinylene) (하이퍼브랜치 PPV를 이용한 유기 EL 소자의 제작)

  • In, In-Sik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.2
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    • pp.163-168
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    • 2009
  • Hyperbranched conjugated polymers (p-HPPV and m-HPPV) with para and meta linkages were synthesized from $A_2$ and $B_4$ type monomers through Wittig polycondensation. The synthesized p-HPPV and m-HPPV were completely soluble in common organic solvents such as chloroform, tetrahydrofuran, 1,2-dichloroethane, etc. and thermal gravimetric analyses showed that p-HPPV and m-HPPV are stable up to $350^{\circ}C$. The molecular weights (from GPC), UV-visible, and photoluminescence maximum peaks of p-HPPV and m-HPPV are characterized in detail. The fabricated EL devices using the synthesized hyperbranched polymers, (ITO/(p-HPPV or m-HPPV)/Al), showed EL emission at about 507 nm and 481 nm (681 nm), respectively. Especially, EL device from m-HPPV were found to exhibit nearly white emission with approximate CIE coordinates of (0.31, 0.34) compared with (0.310, 0.316) of NTSC white color at $100\;cd/m^2$. The good photophysical properties combine with good film-form ability could make these hyperbranched polymers to be a potential candidate for the EL materials.

Characteristics of LB Layer for White Light Organic Electroluminescent Device (백색 유기 EL 소자의 발광층용 LB막 특성)

  • Kim, Ju-Seung;Gu, Hal-Bon;Lee, Kyung-Sup;Song, Min-Jong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.05b
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    • pp.90-93
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    • 2002
  • In the surface pressure-area isotherms of mixed monolayers, mixtures containing as much as 30 mol% of AA form stable condensed monolayer while the monolayer without AA is in the expanded state because PVK take on 3D collapsed. All of the mixed monolayers with 0, 10, 20 and 30 mol% of AA could be readily transferred onto ITO substrate at 16, 17, 24 and 26 mN/m, respectively. The monolayer containing 30 mol% of AA, however, showed a roughness value of 28A and became homogeneous decreasing with the phase separation. We fabricated organic EL device of ITO/CuPc/MEL/BBOT/iLiF/Al using mixed monolayer of 13, 19 and 25 layer deposited by LB method as a emitting layer. In the voltage-current characteristics of EL device, current density was much smaller than that of the spin-coated devices. It may due to the large contact resistance existed at the interface of LB layer/organic layer inhibit carrier injection to the emitting layer. EL spectra of device showed peaks at 450. 470, 505, 555 and 650 nm and the white light emission indicate the CIE coordinate x=0.306, y=0.353.

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Light-Emitting Properties of Organic Electroluminescent Devices using Zinc Complexes (아연 착체를 이용한 유기 EL 소자의 전계발광 특성)

  • Kim, Hong-Soo;Jeong, Noh-Hee
    • Journal of the Korean Applied Science and Technology
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    • v.20 no.4
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    • pp.316-323
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    • 2003
  • Zinc complexes with bis[2-(o-hydroxyphenyl) naphtol [1,2] oxazolato ligands (ZnPBO-4) and its derivatives (ZnPBO-S) were synthesized, and luminescent properties of these materials were investigated. Both the fluorescent emission band and electroluminescent emission band were discussed based on their ligand structure differences. The emission band found that it strongly depends on the molecular structure of introduced ligand. It was tuned from 446 nm to 491 nm by changing the ligand structures. Spreading of the ${\pi}$-conjugation in 2-(o-hydroxyphenyl) group gives rise to a blue shift. The EL properties also showed good consistency with their differences of ligand structure. Bright-blue EL emission with a maximum luminance of 3,100 $cd/m^2$ at 12V, current density, 575 $mA/m^2$ was obtained from the organic light-emitting diodes (OLEDs) using ZnPBO-4 as emitting layer. It was also found that the newly synthesized materials were suitable to be used as emitting materials in organic EL device.