• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1355-1360
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• 2005

We report the development frontiers that are dictating the speed of adoption of polymer organic light emitting diode (P-OLED) technology in market applications. Our presentation includes both the developments taking place in materials and the rapid advances in the manufacturing processes used for solution processable P-OLEDs. On the manufacturing side, the latest progress in ink jet printing process is discussed. On the materials side, we look at both fluorescent and phosphorescent material performance including the CDT development roadmap.

• Proceedings of the KAIS Fall Conference
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• 2004.11a
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• pp.154-156
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• 2004

고도의 정보가 집약되고 응용되기 시작하면서 정보를 표현하고자 하는 방법에 대한 연구는 더욱 절실히 요구되고 있다. 자연색에 가까운 고품질의 색상의 화면을 제공하기 위해 디스플레이의 무게와 크기, 전력소모 등의 많은 부분에 대해 연구가 진행되고 있다. 본 논문에서는 이러한 모든 기능을 충족시켜주는 차세대 디스플레이인 OLED(Organic Light-Emitting Diode)에 대한 구동 드라이브를 디지털 회로에 응용하고자 정확한 동작에 필요한 방법에 대해 소개하고 개선점에 대한 연구를 하였다.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.7-10
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• 2022

A functional polyethylene terephthalate substrate to increase light extraction efficiency of organic light-emitting diodes is studied. We formed nano-structured PET surfaces by controlling the power, gas, and exposure time of the linear ion-beam. The haze of the polyethylene terephthalate can be controlled from 0.2% to 76.0% by changing the peak-to-valley roughness of nano structure by adjusting the exposure cycle. The treated polyethylene terephthalate shows average haze of 76.0%, average total transmittance of 86.6%. The functional PET increases the current efficiency of organic light-emitting diodes by 47% compared to that of organic light-emitting diode on bare polyethylene terephthalate. In addition to polyethylene terephthalate with light extraction performance, by conducting additional research on the development of functional PET with anti-reflection and barrier performance, it will be possible to develop flexible substrates suitable for organic light-emitting diodes lighting and transparent flexible displays.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.260-264
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• 2007

We have studied stability in organic light-emitting diode depending on buffer layer and cathode. A transparent electrode of indium-tin-oxide(ITO) was used as an anode. An electron injection energy barrier into organic material is different depending on a work function of cathodes. Theoretically, the energy barriers for the electron injection are 1.2 eV, -0.1 eV, and 0.0 eV for Al, LiAl, and LiF/Al at 300 K, respectively. We considered the cases that holes are injected to organic light-emitting diode. The hole injection energy barrier is about 0.7 eV between ITO and TPD without buffer layer. For hole-injection buffer layers of CuPc and PEDOT:PSS, the hole injection energy barriers are 0.4 eV and 0.5 eV, respectively. When the buffer layer of CuPc and PEDOT:PSS is existed, we observed the effects of hole injection energy barrier, and a reduction of operating-voltage. However, in case of PVK buffer layer, the hole injection energy barrier becomes high(1.0 eV). Even though the operating voltage becomes high, the efficiency is improved. A device structure for optimal lifetime condition is ITO/PEDOT:PSS/TPD/$Alq_3$/LiAl at an initial luminance of $300cd/m^2$.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.455-466
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• 2016

Organic light-emitting diode (OLED) has drawn a lot of attention in academic and industrial fields, which has been successfully commercialized in mobile phones and TV's. In the field of lighting, unlike the existing incandescent or fluorescent lighting, OLED has distinctive qualities such as surface lighting-emission, large-area, lightweight, ultrathin, flexibility in addition to low energy use. This article introduces prominent fluorescent, phosphorescent, and luminescent materials applied to white OLED (WOLED). The understanding and systematic classification of previously studied substances are expected to be greatly helpful for the development of new luminous materials in future.

• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.131-134
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• 2007

An $ITO/Alq_3/Al$ structure was used to study complex impedance of $Alq_3$ based organic light-emitting diodes. Equivalent circuit was analyzed in a device structure of $ITO/Alq_3/Al$ with a thickness layer of $Alq_3$ of 100 nm. The obtained impedance was able to be fitted using equivalent circuit model of parallel combination of resistance $R_p$ and capacitance $C_p$ with a small series resistance of $R_s$.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1448-1449
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• 2008

Inkjet printing is commonly used in depositing the solution of functional materials on the specific locations of a substrate, and also it can provide easy and fast patterning of polymer films over a large area. Inkjet printing is applicable to fabricating an organic light emitting diode (OLED), since conducting materials used as emissive electroluminescent layers can be manufactured into inks for ink jetting. By using the inkjet technology, we have succeeded in patterning a poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) layer and a poly[2-Methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) layer on the Indume tin oxide (ITO) patterned substrates, and fabricating organic light emitting diodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.492-493
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• 2007

We have investigated Electrical Properties of Organic Light-Emitting Diode depending on Varied Temperature using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the electrical properties of organic light emitting diodes by impedance characteristics of ITO/$Alq_3$/Al. Impedance characteristics was measured complex impedance Z and phase e in the frequency range of 40 Hz to $10^7\;Hz$. From these analyses, we are able to interpret electrical Properties of OLED depending on temperature.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.9
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• pp.1-10
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• 2002

We have done various treatments of indium tin oxide (ITO) surface for organic light-emitting diodes (OLEDs), and investigated the surface states by different surface treatments using atomic force microscopy (AFM) and Auger electron spectroscopy (AES). We have fabricated OLEDs deposited by ultra-high vacuum molecular beam deposition system and studied the characteristics of the OLEDs. We have observed the dramatical improvement of the performance of OLEDs fabricated on ITO substrates treated by $O_2$ plasma treatment reduces the carbon comtamination of ITO surfaces and increases the work function of ITO.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.193-194
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• 2009

This report makes an important correction to estimating angular dependent emission pattern of Organic Light-Emitting Diodes (OLEDs). Today, experiments on measuring angular light intensity of OLEDs are conducted without considering the difference between the view angle identified by photodiode and the actual angle being measured. ITO-TPD-$Alq_3$-LiF-Al Organic Light-Emitting Diode was used to find out the degree of the error. In this case, the difference in average was about $1^*$, which is highly significant. Since the difference varies from case to case, the need for adjustment must be evaluated for each case.