• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.214-217
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• 2002

The internal quantum efficiency of organic light emitting devices(OLEDs) 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 OLEDs. Then triplet excitons can transfer to these phosphorescent molecules and emit light. In this study, multilayer OLEDs with phosphorescent emitter, Iridium complexes were prepared. The devices with a structure of ITO/TPD/Ir complex doped in the host material/Alq3/Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. Using various Ir complexes and the host materials, we fabricated several devices and investigated the device characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1341-1346
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• 2004

The OLED research is gone for two directions. One is material development research, and another one is structural improvement part. All two are thing to heighten luminescence efficiency of OLED. n other to improve luminescence efficiency of OLED Electron - hole pairs must consist much more in the device Their profiles are sensitive to mobility velocity of electrons and holes. In this paper, we demonstrate the difference of velocity between hole and electron by experiments, and compare with a data of simulation and experiment changing hole carrier transport layer thickness, so we get the optimal we improve luminescence efficiency. We suggest improving the efficiency of OLEDS would be to balance the injection of electrons and holes into light emission layer of the device. And, we improve understanding of the various luminescence efficiency through experiments and numerical analysis of luminescence efficiency in variable hole carrier transport layer's thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.543-546
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• 2004

Bias and frequency-dependent impedance is a technique for the investigation of complex conductivity. At low frequency, complex impedance is dominated by resistive component, and at high frequency by capacitive component. We are going to present the results of the bias and frequency-dependent complex impedance in the device structure of $ITO/Alq_3/Al$ in the temperature range between 10K and 300k. And we will show to change radius of Cole-Cole plot. It will be decrease resistance by temperature. Also equivalent electrical circuit and dielectric relaxation can be accomplished by using the complex impedance analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1007-1010
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• 2003

We made use of $Alq_3$ which is the representative light-emitting material. Electric conduction mechanism and luminance characteristics were analyzed in this paper. We have also measured current density-thickness-voltage characteristics with thickness variation from 60 to 400nm. we analyzed the low electric and the high electric field in theoretically. Also, maximum luminous efficiency is the thickness 200 nm of $Alq_3$ in luminous-thickness characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1014-1017
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• 2003

열증착법을 이용하여 copper(II) phthalocyane (CuPc)의 박막을 제작하였다. 기판의 예열 온도를 달리하여 제작된 CuPc의 박막은 ${\alpha}-phase$와 ${\beta}-phase$로 구분할 수 있으며 phase에 따른 결정 구조를 관찰하기 위해 x-ray diffraction을 사용하고 peak의 위치를 관찰하였다. 또한 SEM, UV visible absorption spectra의 변화를 통해 온도에 따라 상전이가 이행해 가는 모습을 구체적으로 관측하였다. 이러한 결정 구조의 변화는 CuPc 박막의 전기전도 특성에 영향을 달리하여 유기발광 소자에 응용이 가능할 것으로 예상된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.351-352
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• 2008

A new high efficient red PhOLED using a host of $Bebq_2$ and double dopants of $(pq)_2$Ir(acac) and SEC-R411 have been fabricated and evaluated. The device doubly doped with $(pq)_2$Ir(acac) and SFC-R411 showed the current efficiency improvement of 22% under a luminance of 10000 cd/$m^2$ in comparision with the device singly doped with SFC-R411. The luminance, current efficiency and central wavelength of the doubly doped device were 9300 cd/$m^2$ at 7V, 11.1 cd/A under a luminance of 10000 cd/$m^2$ and 625 nm, respectively.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.25-28
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• 2000

In this paper, three types of organic electroluminescent devices(OELD) were fabricated on mechanically flexible plastic substrate by using vacuum deposition method. The devices consist of a hole transporting material such as TPD, a light-emitting material such as Alq$\sub$3/ and an electron transporting material, blocking material such as PBD. Electrical and optical properties of these OELDs were measured. This paper shows that organic small molecules based on OELD can be successfully deposited on a flexible plastic substrate. This points open the potential for low cost mass production of flexib]e displays, including roll to roll processing.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.999-1002
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• 2003

In this study, the white organic light emitting device was fabricated using ITO/a-NPD:DCM/a-NPD/BCP/Alq3/Al structure. Blue emission by a-NPD and orange emission by energy transfer between a-NPD and DCM embodied the white emission. The optimal structure of the white OLED is ITO/a-NPD:DCM(50$\square$)/a-NPD(150$\AA$)/BCP(100$\square$)/Alq$_3$(200$\square$)/Al. We varied the doping concentration of DCM properly and obtained high purity white emitting light. The CIE coordinate and maximum luminance of the devices was obtained (0.310, 0.333) and 400cd/$m^2$ at 11Volt.