• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.542-545
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• 2002

High performance organic electroluminescnet(EL) devices which are composed of organic thin multilayer films are fabricated. The basic structure is ITO/Emitting layer/LiF/Al in which have a blended emitting layer. The emitting layer is consisted of a host material(N,N' diphenyl-N,N' (3-methyl phenyl)-l,l'-biphenyl-4,4'diamine)(TPD)) and a guest emitting material(poly(3-hexylthiophehe)(P3HT)). We think that the energy transfer in blending layer occurred from TPD to P3HT. Red emitting multilayer EL devices were fabricated using tris(8-hydroxyqunolinate) aluminum$(Alq_3)$ as electron transport material. The device structure of ITO/blending layer(TPD+P3HT)$/Alq_3$/LiF/Al was employed. In the Voltage-current-luminance characteristics of multilayer device, the device tum on at the 2V and the luminance of $10{\mu}W/cm^2$ obtain at l0V. Red emission peak at 640nm was observed with this device structure. We have presented evidence that the excitation energy migration between a polymeric host and guest has to be explained. And by using multilayer, the red light emitting EL device enhances not only Voltage-current-luminance characteristic but also stability of device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1018-1021
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• 2003

We have synthesized poly(3-hexylthiophene) and studied the optical properties of P3HT for applying to the red emitting materials of organic electroluminescent device. Usually, an organic EL device is composed of single layer like anode/emitting layer/cathode, but additional layer such as hole transport, electron transport and buffer layer is deposited to improve device efficiency. In this study, Multilayer EL devices were fabricated using tris(8-hydroxyquinolinate) aluminum($Alq_3$) as electron transport material, (N,N'-diphenyl-N,,N'(3-methylphenyl)-1,1'-biphenyl-4,4'diamine))(TPD) as hole transport/electron blocking materials and LiF as buffer layer. That is, a device structure of ITO/blending layer(TPD+P3HT)/$Alq_3$/LiF/Al was employed. In the Multilayer device, the luminance of $10{\mu}W/cm^2$ obtained at 10V. And, we present the experimental evidence of the enhancement of the Foster energy transfer interaction in emitting layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.249-252
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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 display-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 light-emitting multilayer organic electroluminescence devices were fabricated vsing Poly (9-vinylcarbaEole) (PVK) and 2- (4-tert-butylphenyl)-5-(4$^{#}$-bis-phenyl) 1,3,4-oxadiazole (PBO) as hole trasport and electron transport material, respectively, where trim(8-hyd roxyquinolinate) aluminum (Al $q_3$) was used as a luminescenct material. A cell structure of glass sub- strate/indume-tin-oxide(ITO)/PCK/Al $q_3$/PBD/Mg:In was employed. Blue emission peak at 510nm was observed with this cell structure.e.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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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

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 센서 박막재료
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• pp.27-31
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• 2001

We fabricated organic electroluminescent(EL) devices with mixed emitting layer of poly(N-vinylcarbazole)(PVK), 2,5-bis(5'-tert-butyl-2-benzoxazoly)thiophene(BBOT), N,N'-diphenyl-N,N'-(3-methyphenyl)-1,1'-biphenyl-4, 4'-diarnine(TPD) and poly(3-hexylthiophene)(P3HT). To improve the external quantum efficiency of EL devices, we added the functional layer to the devices such as LiF insulating layer, carrier confinement layer(BBOT) and hole injection layer(CuPc). In the ITO/emitting layer/Al device, the maximum quantum efficiency at 15V was $1.88{\times}10^{-5}%$. And then, it is increased by a factor of 27 to $5.2{\times}10^{-3}%$ in ITO/CuPc/emitting layer/BBOT/LiF/Al device at 15V.

• 한국응용과학기술학회지
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• 제16권1호
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• pp.41-44
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• 1999

Recently, high luminance and efficiency were realize in organic thin film electroluminescence (EL) cells with multilayer structures including an emitting layer (EML), hole transporting layer (HTL), and an electron transporting layer (ETL). In this study, Bis(10-hydroxybenzo[h]quinolinato)beryllium (Bebq2) was synthesized. PL and EL characteristics of their thin film were investigated by fabricating the devices having a structure of ITO/PVK/Bebq2/Al, ITO/PVK dispersed with TPD/Bebq2/Al. The EL color of these device was greenish and the wavelength of their EL peaks was located, respectly, at 495nm, and 492.5nm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.437-439
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• 2000

The internal quantum efficiency of EL devices using fluorescent organic materials is limited within 25% because of the triplet excitons which can hardly emit light. So there has been considerable interest in finding ways to obtain light emission from triplet excitons. One approach has been to add phosphorescent compounds to one of the layers in an EL device. Then triplet excitons can transfer to these phosphorescent molecules and emit light. In this study, multilayer organic light-emitting devices with phosphorescent emitter, tris (2-phenylpyridine)iridium ($Ir(ppy)_3$) were prepared. The device exhibited power luminous efficiency of 1.07 1m/W at the luminance of $61.6\;cd/m^2$ diriven at the voltage of 9 V and current density of $1.9mA/cm^2$. At the luminance of $100\;cd/m^2$, the luminous efficiency was obtained 1.05 lm/W with the voltage of 9.5 V and the corrent density of $2.8\;mA/cm^2$.