• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1366-1370
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• 2013

A series of phosphorescent iridium(III) complexes 1-4 based on phenylpyrazole were synthesized and their photophysical properties were investigated. To evaluate their electroluminescent properties, OLED devices with the structure of ITO/NPB/mCP: 8% Iridium complexes (1-4)/TPBi/Liq/Al were fabricated. Among those, the device with 3 showed the most efficient white emission with maximum luminance of 100.6 $cd/m^2$ at 15 V, maximum luminous efficiency of 1.52 cd/A, power efficiency of 0.71 lm/W, external quantum efficiency of 0.59%, and CIE coordinates of (0.35, 0.40) at 15.0 V, respectively.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1361-1362
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• 2006

In this research We investigated the effect of UV/O3, $O_3$ treatments of Indium-tin oxide(ITO) surface on the performance of organic light emitting devices(OLEDs). The fundamental structure of OLEDs was ITO(anode) / TPD(Hole Transport Layer) / $Alq_3$ / Al(cathode). We performed UV/O3, $O_3$ treatments and found that both treatments enhanced the performance of OLEDs. Current-Voltage, Luminance-Voltage characteristics were measured at room temperature.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1876-1877
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• 2005

유기 전기 발광 소자(Organic Light-emitting Devices, OLEDs)의 발광 효율과 안정성을 향상시키고자 플라즈마 중합 장비를 이용해서 소자에 버퍼층(buffer layer)을 도입하였다. 플라즈마 중합 방법을 이용해서 성막된 PPMMA를 ITO와 정공 수송층 사이에 버퍼층으로 삽입하여 유기 전기 발광 소자를 제작하였고, 그 특성에 대하여 연구하였다. 기존에 사용되고 있는 버퍼층 공정에 비하여 공정의 단순화 및 비용절감의 효과를 기대할 수 있고, 전기-광학적 특성도 확인할 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.497-499
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• 2005

A portable terminal assistant market grows rapidly every year and it requires many change in research on display devices. Among many newly developing methods, OLED(Organic Light Emitting Diode) is considered an advanced flat display device because its excellent characteristics, including high speed response, full color performance, low power consumption and flux of panel. However changes in the market of display shows that the market will require 3-dimensional images, but it is hard for existing 2-dimensional displays to make 3-dimensional images. Therefore we will try to find various methods such as holograms. In this paper, we will show existing flat displays can make 3-dimensional images by applying Lenticular Screen printing techniques on the organic semiconductor display device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.412-413
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• 2006

The electrical conduction mechanism of ITO / Terbium tris - (1 - phenyl - 3 - methyl - 4 - (tertiarybutyryl) - pyrazol - 5 - one) triphenylphosphine oxide [$(tb-PMP)_3Tb-(Ph_3PO)$]/Mg/Al devices has been investigated. The calculation of electric field in single layer organic layer between cathode and anode shows the uniform distribution for the electron injection barrier of over 1.4 eV. The measured current-voltage curve shows well matching with the calculated curve based on the tunneling injection of electron under the uniform distribution of electric field.

• Prospectives of Industrial Chemistry
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• v.22 no.3
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• pp.1-5
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• 2019

차세대 디스플레이 소자로서 상용화된 유기발광소자(OLED)는 현재 진공기반의 증착공정을 통해서 제작되므로 제조공정 비용이 높다. 진공 증착공정을 용액공정으로 교체하면 공정 비용을 크게 절감할 수 있지만, 용액공정으로 다층 박막 구조를 형성하기 어렵다는 문제점이 있다. 다층 구조를 제작할 때 이미 형성된 하부 박막 위에 새로 형성되는 박막이 하부 박막에 영향을 주기 때문이다. 이를 해결하기 위한 방법으로서 용액 공정용 잉크 용매의 내용제성을 증가시켜 상부 박막을 코팅할 때 하부 박막이 용해되거나 손상을 입지 않도록 하는 가교형 소재를 이용한 방법이 있다. 본 원고에서는 OLED 소자를 용액공정으로 제작하기 위한 가교형 정공 수송 재료의 특징과 개발 현황에 대해 소개하고자 한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.313-313
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• 2009

OLED 소자는 직접발광, 광시야각, 그리고 빠른 응답속도 때문에 동영상에 적합하여 최근 각광받고 있는 디스플레이장치 중의 하나이다. OLED 소자의 양극재료로는 높은 광투과율과 $\sim10^{-4}{\Omega}\;cm$ 수준의 낮은 전기 비저항을 갖는 ITO (Sn-doped $In_2O_3$)가 널리 사용되고 있다. 하지만 원료 물질인 인듐의 수급량 부족으로 인한 문제점과 독성, 저온증착의 어려움, 스퍼터링시 음이온 충격에 의한 막 손상으로 저항의 증가의 문제점이 있고, 또한 액정디스플레이의 투명전극으로 사용될 경우 $400\;^{\circ}C$정도의 높은 온도와 수소 플라즈마 분위기에서 장시간 노출 시 열화로 인한 광학적 특성변화가 문제가 된다. 반면에 Al이 도핑 된 ZnO (AZO)박막은 넓은 밴드갭 (3.37eV)와 400nm에서 700nm 사이의 가시광 영역에서 80% 이상의 우수한 투과성을 지니고 있다. 특히 Al이 도핑된 ZnO는 박막의 전기적 특성이 크게 향상되어 디스플레이나 태양전지로의 응용이 가능하다. 또한 비교적 낮은 비용과 플라즈마에서의 안정성, 무독성, 그리고 전기전도성과 같은 많은 이점이 있다. 그 결과 AZO 박막은 ITO기판을 대안하는 지원물질로 활발히 연구가 진행되고 있다. 본 연구에서는 TCO 박막의 면 저항과 표면 거칠기에 따른 OLED 소자의 특성을 분석하였다. ITO와 AZO 박막은 챔버 내 다양한 가스 분위기(Ar, Ar+$O_2$ and Ar+$H_2$)에서 R.F Magnetron Sputtering방법으로 증착하였다. TCO 박막의 구조적인 이해를 돕기 위해서 X-ray diffraction 과 FESEM으로 분석하였다. 광학적 투과도와 박막의 두께는 ultraviolet spectrophotometer (Varian, cary-500)와 surface profile measurement system으로 각각 측정하였다. 면저항 charge carrier 농도, 그리고 TCO 박막의 이동도와 같은 전기적특성은 four-point probe와 hall effect measurement(HMS-3000)로 각각 측정하였다. TCO 박막의 표면 거칠기 조절을 위해 photo lithography 공정을 사용하여 TCO 박막을 화학에칭 하였다. 미세사이즈 패턴 마스크가 사용되었으며 에칭의 깊이는 에칭시간에 따라 조절하였다. TCO 박막의 표면 형태는 FESEM과 AFM으로 관찰하였다. 투명전극으로 사용되는 ITO 및 AZO 기판 상용화를 위해 ITO 및 AZO 기판 위에 ${\alpha}$-NPB, Alq3, LiF, Al 의 순서로 증착 및 패터닝함으로써 OLED 소자를 제작하였다. 전류밀도와 전압 그리고 발광휘도와 전압과 같은 전기적 특성은 spectrometer(minolta CS-1000A)를 이용하여 측정하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.380-380
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• 2010

Currently, organic light-emitting diodes (OLEDs) have been proven of their readiness for commercialization in terms of lifetime and efficiency. In accordance with emerging new technologies, enhancement of light efficiency and extension of application fields are required. Particularly inverted structures, in which electron injection occurs at bottom and hole injection on top, show crucial advantages due to their easy integration with Si-based driving circuits for active matrix OLED as well as large open area for brighter illumination. In order to get better performance and process reliability, usually a proper buffer layer for carrier injection is needed. In inverted top emission OLED, the buffer layer should protect underlying organic materials against destructive particles during the electrode deposition, in addition to increasing their efficiency by reducing carrier injection barrier. For hole injection layers, there are several requirements for the buffer layer, such as high transparency, high work function, and reasonable electrical conductivity. As a buffer material, a few kinds of transition metal oxides for inverted OLED applications have been successfully utilized aiming at efficient hole injection properties. Among them, we chose 2 nm of $WO_3$ between NPB [N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] and Au (or Al) films. The interfacial energy-level alignment and chemical reaction as a function of film coverage have been measured by using in-situ ultraviolet and X-ray photoelectron spectroscopy. It turned out that the $WO_3$ interlayer substantially reduces the hole injection barrier irrespective of the kind of electrode metals. It also avoids direct chemical interaction between NPB and metal atoms. This observation clearly validates the use of $WO_3$ interlayer as hole injection for inverted OLED applications.

• Fashion & Textile Research Journal
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• v.23 no.6
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• pp.860-868
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• 2021

Clothing has a very important role in human life, and it is the most human-friendly platform because humans wear it in almost all the time. In the recent years, smart clothing integrated with various functions is solidifying its position as the core of next-generation Information and Communications Technology(ICT). With this global trend, the smart textiles, textiles embedded with electronic devices that are capable of performing various functions, have been attracting a lot of attention. Therefore, various research activities on the smart textiles are in progress, and the global market outlook for the smart textiles is also showing rapid growth. Among the various smart textile technologies, the textile/fiber-based wearable display has been attracting more attention because it is an essential element for wearers to intuitively control the functions integrated in the smart textiles. This paper provides insightful information and the technological elements of organic light emitting diodes(OLEDs) display, which have been evaluated as the most ideal device for luminescent clothing. Since, OLEDs have many advantages such as light weight, extremely thin thickness and great flexibility, the textile/fiber-based wearable OLEDs can be worn without any inconvenience. In addition, by introducing previous studies on the textile/fiber-based OLED displays, we intend to consider the commercial potential of the textile/fiber-based smart luminescent clothing using the OLED technologies.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.10-17
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• 2024

This paper discusses Chip On Film (COF) technology, one of the key technologies in flexible packaging to enable miniaturization and flexibility of electronic devices. COF attaches Display Driver IC (DDI) directly to a flexible polyimide substrate, enabling lightweight and reduced thickness for high-resolution displays. COF technology is primarily used in high-performance display panels, such as organic light emitting diode (OLED) displays, and plays a key role in portable electronic devices, such as smartphones and wearable devices. This study analyzes the key components of COF and advances in bonding technology. In particular, the introduction of modern bonding techniques, such as thermo-compression bonding and thermo-sonic bonding, has led to significant improvements in bonding reliability and electrical performance. These bonding techniques enhance the mechanical stability of COF packages while maintaining high electrical connectivity in fine-pitch structures. This paper will discuss the future development of COF bonding technology and its challenges and explore its potential as a next-generation display and advanced packaging technology.