• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.698-701
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• 2007

A top emission organic light emitting diode comprising of a triple anode on polycarbonate $film/TNATA/NPB/Alq_3:C545T/cathodes$ has been fabricated. The triple layer structure of Cr/Al/Cr allowed for fabrication of a crack-free anode and provided better higher work function than ITO anode.The anode showed compatibility with flexible plastic substrate and no crack was formed during bending test while ITO anode showed crack.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 춘계 학술대회논문집
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• pp.152-157
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• 2002

전산유체역학분야의 고속 연산을 위해서 병렬처리가 보편화되고 있으며 이러한 병렬해석은 주로 클러스터에서 저렴한 비용으로 수행되고 있다. 전산유체역학을 위한 클러스터 컴퓨터에서의 해석프로그램의 성능은 클러스터에 사용되는 프로세서의 성능뿐만 아니라 클러스터 내부의 통신 장비의 성능에 크게 좌우된다. 본 논문에서는 클러스터 컴퓨터의 구축에 널리 사용되고 있는 Myrinet2000, Gigabit Ethernet, Fast Ethernet 등의 네트웍 장치에 대해서 Netpipe, Linpack, NAS NPB, 그리고 MPINS2D Navier-Stokes 해석프로그램을 사용하여 성능을 비교하였다. 이를 통해서 향후 전산유체역학을 위한 클러스터 구축시 최대의 가격대 성능비를 얻을 수 있는 방법을 제시하고자 한다.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.86-88
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• 2004

정공주입 버퍼층(PTFE)두께에 변화에 따른 유기발광소자 전압-전류-휘도 효율을 측정한 결과 ITO/PTFE/Al 구조에서 두께가 증가하면 전류 밀도 및 전압이 증가하며, 두께가 0.7 (nm)일 때 부성 저항 영역이 나타났었고, ITO/PTFE/NPB/$Alq_3$/Al 구조에서 두께가 1.0 [nm]에서는 가장 좋은 휘도와 효율을 나타났었다. 두께가 증가하면 이것은 PTFE 내의 정공의 이동을 어렵게 하기 때문에 효율이 감소하는 것으로 판단된다. 그래서 적당한 PTFE 두께만이 가장 좋은 휘도와 효율을 얻을 수가 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.475-476
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• 2005

Efficient electron injection is essential to achieve bright and efficient organic light-emitting diodes (OLEDs). In spite of high work function of Al, it is a common cathode because of its stability. In this paper, to overcome the poor electron injection in OLEDs with Al cathode, OLEDs with various composite cathodes were fabricated and investigated using a conventional OLEDs structure of indium tin oxide ITO/NPB(40 nm)/$Alq_3$(50 nm)/Al. composite cathodes were composed of alkaline materials such as Ca and Li, Al deposition or codeposited with AI. We showed best performance at the device with composite cathode (LiF/Al).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.493-494
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• 2006

We have demonstrated highly efficient WOLED with two separated emissive layers using a blue fluorescent dye and a red phosphorescent dye. we also obtain stable $CIE_{x,y}$ coordinates with two-layered WOLEDs. The device structure was ITO/2-TNATA/NPB/two separated emissive layers/Bphen/Liq/Al. The maximum luminous efficiency of the device was 11.6 cd/A at $20\;mA/cm^2$ and $CIE_{x,y}$ coordinates varied from (x = 0.33, y = 0.37) at 6V to (x = 0.28, y = 0.35) at 14V.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.67-68
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• 2006

Organic light-emitting devices (OLEDs) with the high efficiency and long lifetime are of growing interest in next-generation displays. Among the factors influencing OLEDs properties, one of unstable factor is $Alq_3$ cationic species caused by the excess holes resided in $Alq_3$ layer. Therefore, we suppressed the accumulation of excess holes by using the mixed-hole transporting layer (MHTL) of NPB and CBP in multilayer green OLEDs. The devices with MHTL showed improved characteristics in the luminance efficiency and lifetime. More characteristics and the carrier transport mechanism will be discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.254-255
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• 2012

Interest in nano-crystalline silicon (nc-Si) thin films has been growing because of their favorable processing conditions for certain electronic devices. In particular, there has been an increase in the use of nc-Si thin films in photovoltaics for large solar cell panels and in thin film transistors for large flat panel displays. One of the most important material properties for these device applications is the macroscopic charge-carrier mobility. Hydrogenated amorphous silicon (a-Si:H) or nc-Si is a basic material in thin film transistors (TFTs). However, a-Si:H based devices have low carrier mobility and bias instability due to their metastable properties. The large number of trap sites and incomplete hydrogen passivation of a-Si:H film produce limited carrier transport. The basic electrical properties, including the carrier mobility and stability, of nc-Si TFTs might be superior to those of a-Si:H thin film. However, typical nc-Si thin films tend to have mobilities similar to a-Si films, although changes in the processing conditions can enhance the mobility. In polycrystalline silicon (poly-Si) thin films, the performance of the devices is strongly influenced by the boundaries between neighboring crystalline grains. These grain boundaries limit the conductance of macroscopic regions comprised of multiple grains. In much of the work on poly-Si thin films, it was shown that the performance of TFTs was largely determined by the number and location of the grain boundaries within the channel. Hence, efforts were made to reduce the total number of grain boundaries by increasing the average grain size. However, even a small number of grain boundaries can significantly reduce the macroscopic charge carrier mobility. The nano-crystalline or polymorphous-Si development for TFT and solar cells have been employed to compensate for disadvantage inherent to a-Si and micro-crystalline silicon (${\mu}$-Si). Recently, a novel process for deposition of nano-crystralline silicon (nc-Si) thin films at room temperature was developed using neutral beam assisted chemical vapor deposition (NBaCVD) with a neutral particle beam (NPB) source, which controls the energy of incident neutral particles in the range of 1~300 eV in order to enhance the atomic activation and crystalline of thin films at room temperature. In previous our experiments, we verified favorable properties of nc-Si thin films for certain electronic devices. During the formation of the nc-Si thin films by the NBaCVD with various process conditions, NPB energy directly controlled by the reflector bias and effectively increased crystal fraction (~80%) by uniformly distributed nc grains with 3~10 nm size. The more resent work on nc-Si thin film transistors (TFT) was done. We identified the performance of nc-Si TFT active channeal layers. The dependence of the performance of nc-Si TFT on the primary process parameters is explored. Raman, FT-IR and transmission electron microscope (TEM) were used to study the microstructures and the crystalline volume fraction of nc-Si films. The electric properties were investigated on Cr/SiO2/nc-Si metal-oxide-semiconductor (MOS) capacitors.

• 대한화학회지
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• 제54권3호
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• pp.291-294
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• 2010

본 연구에서는 다양한 농도의 BCzVBi를 청색 형광도판트, DPVBi를 청색 호스트 물질로 적용한 청색OLED 소자를 제작하였다. 최적화된 고효율 청색 OLED 소자의 적층 구조는 NPB (500 ${\AA}$)/DPVBi:BCzVBi-6%(150 ${\AA}$)/$Alq_3$(300 ${\AA}$)/Liq(20 ${\AA}$)/Al (1000 ${\AA}$)으로 구성되었다. 청색 OLED의 최대휘도는 구동전압 13.8V에서13200 cd/$m^2$이고 전류밀도 및 최대효율은 각각 1000 cd/$m^2$의 휘도에서 26.4 mA/$cm^2$, 구동전압 3.9 V에서 4.24 cd/A 이었다. 도핑된 청색 OLED 소자의 발광효율은 도핑되지 않은 소자의 2배에 이른 반면 색좌표는 (0.16, 0.19)로 서로 비슷하였다. BCzVBi가 6% 도핑된 청색 OLED 445 nm와 470 nm에 2개의 EL 스펙트럼의 Peak이 존재하는 반면 도핑되지 않은 순수한 DPVBi 청색OLED 소자는 456 nm에서의 유일한 Peak만을 보여주고 있다. 이는 호스트 물질인 DPVBi의 LUMO와 도판트 물질인 BCzVBI의 LUMO 사이에 분자 진동에 의한 페르스터 에너지 전이에 기인한 것이다.

• 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.