• 한국전기전자재료학회논문지
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• 제21권2호
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• pp.173-177
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• 2008

We have developed the transparent passivation layer for top emission organic light emitting diodes using CsCl thin film by the thermal evaporation method. The CsCl film was deposited on the Ca/Ag semitransparent cathode. The optical transmittance of Ca/ Ag/CsCl triple layer is higher than that of Ca/Ag double layer in the visible range. The device with a structure of glass/Ni/2-TNATA/a-NPD/Alq3:C545T/BCP/Alq3/Ca/Ag/CsCl results in higher efficiency than the device without CsCl passivation layer. The device without CsCl thin film shows a current efficiency of 7 cd/A, whereas the device passivated with CsCl layer shows an efficiency of 10 cd/A. This increase of efficiency isresulted from the increased optical extraction by the CsCl passivation layer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.180-180
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• 2016

최근 디스플레이 시장의 주요 키워드는 flexible organic light emitting diode (OLED) 이다. OLED 소자의 수명을 결정하는 가장 큰 요인 중의 하나는 공기 중의 O2와 H2O에 의한 유기물의 열화이다. 따라서 공기 중의 O2나 H2O가 유기물에 쉽게 침투하는 것을 막는 것은 소자의 수명 향상을 위하여 필수적이라 할 수 있다[1-3]. SiNx 박막은 경질로 투과성이 우수하며, 화학적 불활성인 특성으로 이러한 Barrier 역할로 연구되어 산업분야에 다양하게 응용되고 있다[4]. SiNx 박막은 일반적으로 plasma enhanced chemical vapor deposition (PECVD) 기술을 이용하여 증착되는데 기존의 PECVD 기술을 이용한 SiNx 박막은 낮은 water vapor transmission rate (WVTR) 등의 문제점들로 인해 한계점이 들어났다. 본 연구에서는, flexible display의 thin film encapsulation (TFE) 공정에서의 적용을 알아보기 위해 $370{\times}470$ size를 증착할 수 있는 In-line 장비를 이용하였으며, 기존의 PECVD 기술의 문제점으로 지적되고 있는 낮은 WVTR을 해결하기 위하여 저온 (<$100^{\circ}C$) 선형 PECVD 기술을 이용하여 WVTR을 개선하고자 하였다. 공정가스로는 SiH4와 NH3를 사용하였으며, SiH4 Carrier 가스로 He을 추가적으로 사용하였다. 또한 공정 압력은 100mTorr를 유지하였다. 증착된 SiNx 박막의 물리적, 화학적 특성 분석을 위해 분광엘립소메타, field emission electron microscopy (FESEM), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) 등을 이용하여 측정하였으며, 박막에 투습되는 수분의 양은 MOCON사의 AQUATRAN 2(W)로 측정하였다. OLED 소자를 구현하기 위해서는 기본적으로 봉지층에 투습되는 양을 $10-6g/m2{\cdot}day$ 이하로 막아줘야 한다고 알려져 있으나, 기존의 PECVD 기술을 이용하여 제작된 SiNx 박막의 WVTR은 $10-2{\sim}10-3g/m2{\cdot}day$ 레벨의 WVTR 결과를 보이고 있다. 본 연구에서 사용된 저온 선형 PECVD 기술을 이용하여 제작된 SiNx 박막의 WVTR은 $5.0{\times}10-5g/m2{\cdot}day$ 이하의 개선된 결과를 확인 할 수 있었다. 또한 flexible display에 적용하기 위해 SiNx 박막의 두께를 최소화한 100nm의 두께에서도 WVTR은 $5.0{\times}10-5g/m2{\cdot}day$ 이하의 결과가 유지됨을 알 수 있었다.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.82-86
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• 2024

With the growing field and growing interest in transparent organic light-emitting diodes (TOLED) in the industry, various attempts are being made to improve the transmittance and performance of TOLED. TOLEDs are expected to be used in next-generation displays such as mixture reality (MR) displays, displayable windows, televisions, etc. This study presents a mesh TOLED with better transmittance and luminescence characteristics than existing TOLEDs through an in-situ vacuum deposition method that does not require additional processes such as photolithography and etching. In this study the mesh TOLED's cathode consists of Mg: Ag 1:9 electrode. Mesh patterns are interconnected with a 6 nm layer of interlayer. We approached transmittance improvement up to 30% at 555 nm at the cathode electrode with similar current injection character, also we improved lumination characteristics up to 23% at 7 V driving condition.

• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.348-352
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• 2008

Deformation of the shadow mask is one of the problems encountered during the deposition of organic materials for manufacturing large size organic light emitting diode (OLED). The larger the glass substrate, the larger the shadow mask becomes. As the size of the shadow mask increases, its deformation becomes more severe, thereby making it difficult to deposit organic materials in a precise pattern on a substrate. In this paper, a new method for reducing drooping of the shadow mask for large size OLED vapor depositions is proposed. The proposed shadow mask with cross stripe wires has higher stiffness than the pure shadow mask, which results in reducing drooping of the shadow mask. A commercial FEM program, ANSYS, is used for the evaluation of the proposed shadow mask. The analysis showed that the shadow mask with cross stripe wires have an effect on reducing drooping about 18.6% or more.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.569-573
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• 2014

We demonstrate a low-cost, superbly efficient way of etching for the nano-, and micro-sized pyramid patterns on (100)-oriented Si wafer surfaces for use as a patterned master. We show a way of producing functional optical films for the viewing angle direction brightness-enhancement of Lambertian LED (light emitting diode)/OLED (organic light emitting diode) planar lighting applications. An optimally formulated KOH (Potassium hydroxide) wet etching process enabled random-positioned, and random size-distributed (within a certain size range) pyramid patterns to be developed over the entire (100) silicon wafer substrates up to 8" and a simple replication process of master patterns onto the PC (poly-carbonate) and PMMA (poly-methyl methacrylate) films were performed. Haze ratio values were measured for several film samples exhibiting excellent values over 90% suitable for LED/OLED lighting purposes. Brightness was also improved by 13~14% toward the viewing angle direction. Computational simulations using LightTools$^{TM}$ were also carried out and turned out to be in strong agreement with experimental data. Finally, we could check the feasibility of fabricating low-cost, large area, high performance optical films for commercialization.

• 한국응용과학기술학회지
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• 제21권4호
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• pp.274-278
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• 2004

In this study, hetero-electrode structures have been fabricated to increase luminescence efficiency. The presence of a thin layer of Sn or Ag at the organic-aluminum interface enhanced both electron injection efficiency and electroluminescence when compared to OLEDs using homogeneous electrode. In this paper, the effect of the cathode using Sn/Al hetero electrode structure is observed. Electric properties of the OLED using Sn/Al hetero cathode are improved in comparison of only Al cathode. The hetero-electrode existing different energy level induces the advanced structure of OLED can accumulate electron density. The luminescence efficiency of OLED with Sn/Al of Ag/Al cathode is higher because of their higher electron injection efficiency. And, the turn on voltage of the OLED device using Sn thin layer is lowest as about 10 V.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.449-449
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• 2007

OLED has many advantages of low voltage operation, self radiation, light weight, thin thickness, wide view angle and fast response time to overcome existing liquid crystal display (LCD)'s weakness. Therefore, It draws attention as promising display and has already developed for manufactured goods. Also, OLED is regarded as a only substitute of flexible display with a thin display. A considerable portion of the light originating film emissive centers buried in a solid film never escapes due to internal reflection at the air-film interface and is scattered as edge emission or dissipated within the solid film This is one of the major reasons why the luminous power efficiency of OLED remains low, in spite of research progress in OLED. Although several ways of overcoming this difficulty have been reported, no comprehensive method has been proposed yet. In this paper, we propose that use of anti-reflective coating layers.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.1-6
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• 2008

고효율 녹색 인광 유기발광다이오드를 개발하기 위해 소자 구조를 ITO/2-TNATA/NPB/TCTA/CBP:$7%Ir(ppy)_3$/BCP/SFC-137/LiF/Al로 설계 제작하고 그 전계발광 특성을 평가하였다. 소자 제작에서 발광 호스트의 두께를 $150{\AA}{\sim}350{\AA}$ 범위로 변화시켜, 전계발광 특성을 비교해 본 결과, CBP두께가 약 $300{\AA}$ 부근일 때 가장 우수한 휘도 특성이 얻어졌다 전류 효율은 CBP두께가 $300{\AA}{\sim}350{\AA}$범위일 때 거의 포화되어 최대로 나타났다. $CBP(300{\AA}):7%Ir(ppy)_3-EML$ 층을 갖는 PhOLED(phosphorescent organic light emitting diode)의 전류 밀도, 휘도, 그리고 전류 효율은 10V의 인가전압에서 각각 $40mA/cm^2,\;10000cd/m^2$, 25cd/A로 나타났다. 또한 이 소자의 최대 전류효율은 $160cd/m^2$의 휘도 상태에서 40.5cd/A로 나타났다. 발광 스펙트럼은 512nm의 중심 파장과 약 60nm의 FWHM(Full Width Half Maximum)을 나타내었으며, CIE (Commission Internationale de I'Eclairage)도표 상에서 색 좌표는 (0.28,0.63)으로 나타났다.

• 대한전자공학회논문지SD
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• 제44권6호
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• pp.83-88
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• 2007

본 논문에서는 유기발광다이오드 구동 IC의 기능을 검증하기 위하여 PLI(Programing Language Interface)를 이용한 검증방법을 제안한다. 기능 검증을 하기 위하여 HDL(Hardware Description Language) 시뮬레이터와 PLI, GUI(Graphic User Interface) 환경의 이미지 뷰어를 이용한다. 본 논문에서 제안하는 유기발광다이오드 구동 IC의 기능 검증 방법을 이용 할 경우 종래의 기능 검증 방법을 이용 할 때 보다 40배의 실행 시간 이득을 얻을 수 있다. 제안한 방법을 이용할 경우 디스플레이 구동 IC의 설계 단계에서 기능 검증을 효율적으로 할 수 있을 것이다.