• The Optical Journal
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• s.99
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• pp.69-74
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• 2005

LCD를 극복할 수 있는 유일한 대안이 AM OLED라는 판단에 따라 일본업체들은 소형 AM OLED의 초기 생산체제에 돌입했다. 이에 비해 국내에서는 AM OLED 사업화의 필요성은 인정하고 있으나, 여전히 시장 지배력을 확보하고 있는 TFT LCD에 무게 중심을 두고 있어 AM OLED는 일본보다 사업화가 늦어질 것으로 보인다. 현재 세계 OLED 시장은 2006년에는 10억 달러, 2009년에는 20억 달러로 성장할 것으로 예상되는 등 2011년까지 연평균 30% 이상의 안정적인 성장세를 보일 것으로 전망된다. 이들 대부분은 중소형 모바일 제품에 탑재되는 것이다.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1785-1788
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• 2007

We investigated the effect on light extraction in OLED by introducing aluminum micro bump light scattering reflector. By attaching the micro bump reflector to a both side emission OLED, we found that the light extraction was 1.7 times larger than a simple flat reflector. We fabricated a 20.8” inch WXGA full color AM-OLED by integrating the micro bump scattering reflector.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.837-840
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• 2007

We propose a novel digital driving method for AM-OLED (Active Matrix-Organic Light Emitting Diode) display. Proposed method modulates $V_{DD}$ so that luminance may be weighted in accordance with the bit significance. We can increase the minimum emission time or slower scan circuits are applicable by using proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.43-46
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• 2007

Though bottom emission AM-OLED has advantages in respect of mass production, the bottom emission type is underrated due to its low aperture ratio and low color gamut, compared with top emission type. In this paper, we demonstrate that the color gamut up to 89 % can be simply achieved by depositing dielectric multilayers, whose thicknesses are determined using an optical simulation program, prior to formation of Si layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.239-244
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• 2007

Highly efficient and stable white PIN OLED structures have been developed with a focus on possible AM display applications. Due to the use of the novel air-stable Novaled n-dopant material NDN26, the mass production compatibility of the PIN approach is improved. With both a conventional n-dopant, NDN1, and a novel air-stable n-dopant, NDN26, similar performance in efficiency and lifetime are reached. Based on highly a stable red fluorescent emitter system, the Novaled PIN approach allows for reaching ultra-long lifetimes of 1,000,000 hours at a brightness of $1,000\;cd/m^2$, both for top and for bottom emission layouts. Furthermore, inverted PIN structures for a possible use in a-Si backplane applications for AM displays are shown. With a phosphorescent green emitter system it could be demonstrated that for bottom and inverted as well as non-inverted top emission, a brightness of $1,000\;cd/m^2$ can be reached at below 3 V. In addition to low operating voltages and long lifetimes, PIN OLEDs also enable for device structures with extremely low operating voltage drifts, a feature of increasing importance for future AM display developments.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.330-332
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• 2009

Highly stable bottom gate thin film transistors(TFTs) with a zinc indium tin oxide(Zn-In-Sn-O:ZITO) channel layer have been fabricated by rf-magnetron co-sputtering using a indium tin oxide(ITO:90/10), a tin oxide and a zinc oxide targets. The ZITO TFT (W/L=$40{\mu}m/20{\mu}m$) has a mobility of 24.6 $cm^2$/V.s, a subthreshold swing of 0.12V/dec., a turn-on voltage of -0.4V and an on/off ratio of >$10^9$. When gate field of $1.8{\times}10^5$ V/cm was applied with source-drain current of $3{\mu}A$ at $60^{\circ}C$, the threshold voltage shift was ~0.18 V after 135 hours. We fabricated AM-OLED driven by highly stable bottom gate Zn-In-Sn-O TFT array.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.269-274
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• 2004

Current delivery system, in which the analog current produced by a unique DAC circuit is stored into a current-memory circuit and delivered in a time-divided sequence, shows variation of output current as low as 4% in a current source data-driver IC for AM-OLED driven by a current-programmed method without any fuse repairing after fabrication. This driver IC has 54 outputs and can sink constant current as low as 3 ${\mu}A$ with 6-bit analog levels. Such a low current level without variation can hardly be obtained by an ordinary MOS transistor because the current level is in the sub-threshold region and changes exponentially with threshold voltage variation. Thus we adopted a current mirror circuit composed of bipolar transistors to supply well-controlled current within a nano-ampere range.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.441-445
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• 2007

In this paper we demonstrated the applications of OTFTs (organic thin film transistors) to flexible displays such as AM-EPD (active matrix electrophoretic display) and AM-OLED (active matrix organic light emitting diode), and also to integrated circuits. The OTFTs using pentacene semiconductor layer and PVP gate dielectric and Au S/D electrodes exhibited good performance for AM-EPD with the mobility of $0.59\;cm^{2}/V.sec,$ and with also good uniformity over 2.5" diagonal area. However, it is nor enough for AM-OLED requiring the mobility larger than $1\;cm^{2}/V.sec$ for large area displays. The integrated circuits also worked, producing the operating frequency of 1MHz. We need to develop a fabrication process to reduce parasitic capacitance for high frequency operation.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1206-1209
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• 2007

Both PM-OLEDs and AM-OLEDs are now in production. However, manufacturers are still concerned about life-time, voltage drift, operating voltage and efficiency in order to develop larger displays. Most material suppliers seem to be focussing on emitters and the benefits of introducing suitable charge transporters have been largely unexplored. OLED-T has developed a novel organic electron injector (Trade Name: EI-101) which evaporates at a very low temperature of $300^{\circ}C$ as opposed to the conventional LiF which requires $580^{\circ}C$. EI-101 has been found to increase the lifetime by up to 12%, reduce the voltage drift by up to 61% and increase the efficiency by up to 15%. The material can be handled in air and in situ Q-mass spectroscopy on extended thermal evaporation has confirmed its high stability for use in mass production.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1163-1167
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• 2008

Since Samsung SDI and Sony started mass production of AM-OLED display for mobile/TV applications, OLED technology has emerged as leading candidate among the many technologies under development for next generation Flat panel displays. P-OLED (Polymer Organic Lighting Emitting Diode) technology, a class of OLED, is gathering momentum towards commercialization. P-OLED technology has made tremendous progress in terms of display performance (including life time, efficiency and color gamut) and in the maturity of ink jet printing process and equipment. In order to get into the mobile/TV application market successfully, P-OLED display technology must meet the following display makers' requirements: (1) P-OLED Display Performance in terms of lifetime, efficiency, and color coordinates, (2) Low Cost Manufacturing Technology such as "Solution Processable Printing Technology". P-OLED technology has already overcome many of the hurdles to mass manufacturing. In this paper, the latest developments in ink jet printing technology, including P-OLED material performance, is discussed.