• Korean Chemical Engineering Research
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• 제47권4호
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• pp.418-423
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• 2009

유기발광다이오드(OLED)에서 정공 주입층(hole injection layer, HIL)으로 사용되는 poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)에 관능성기가 치환된 MWCNT(multi-wall carbon nanotube)를 도입하여 PEDOT:PSS-MWCNT 나노 복합재 박막을 제조하였다. PEDOT:PSS-MWCNT 박막 층은 ITO 유리 위에 스핀 코팅되어 제조하였으며 FT-IR과 UV-Vis 및 SEM을 이용하여 박막의 투과도 및 개질된 MWCNT 함량에 따른 박막의 모폴로지 특성을 관찰하였다. 또한, ITO/PEDOT:PSS-MWCNT/NPD/$Alq_3$/Al 다층 소자를 제조하여 J-V 및 L-V 특성을 고찰하였다. 산 처리에 의해 관능성기가 도입된 MWCNT는 PEDOT:PSS 용액 내에서 분산성이 확인되었으며, 제조된 박막은 우수한 투과도 특성을 보였다. 다층 소자 특성에서 PEDOT:PSS 층에 개질된 MWCNT 도입으로 MWCNT의 함량이 증가함에 따라 다층 소자의 전류 밀도가 증가됨을 확인하였고, 반면에 소자의 휘도는 급격히 감소하는 특성을 보였다. 이것은 MWCNT에 의하여 전하 이동은 수월하게 하였으나 MWCNT가 가지는 정공을 가두는 성질에 의해 정공 이동도가 저하되었기 때문인 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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• pp.65-66
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• 2008

The realization and origin of p-type ZnO are main issue for photoelectronic devices based on ZnO material. N-doped and nominally undoped p-type ZnO films were achieved on silicon (100) and homo-buffer layers by RF magnetron sputtering and post in-situ annealing. The undoped film shows high hole mobility of 1201 $cm^2V^{-1}s^{-1}$ and low resistivity of $0.0454\Omega{\cdot}cm$ with hole concentration of $1.145\times10^{17}cm^{-3}$. The photoluminescence(PL) spectra show the emissions related to FE, DAP and defects of $V_{Zn}$, $V_O$, $Zn_O$, $O_i$ and $O_{Zn}$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.74-77
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• 2006

Thin $AuO_x$ layer was formed by $O_2$ plasma treatment on Au electrode. The surface work function of plasma treatment showed higher by 0.5 eV than that of bare Au, reducing the hole injection barrier at the Au/pentacene interface. Using $O_2$ plasma-treated Au source-drain electrodes, the field-effect mobility of bottom-contact pentacene-OTFT was increased from 0.05 to 0.1 $cm^2/Vs$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1619-1622
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• 2005

The ultra thin hole injection layer (HIL) was deposited on an indium-tin-oxide (ITO) anode by using an ion beam assisted d eposition (IBAD) for the fabrication of an polymeric electroluminescence device for the first time. The device with the HIL deposited by IBAD has higher external quantum efficiency than the device with the HIL by conventional thermal evaporation. It is found that the deposited HIL by IBAD has high surface coverage on ITO anode in a few nm regions because the HIL prepared has high adatom mobility by ion beam energy.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1061-1064
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• 2009

Through dark injection space-charge-limited current (DI-SCLC) and trap-free SCLC measurements, it has been demonstrated that an indium tin oxide (ITO)/buckminsterfullerene ($C_{60}$) electrode can form a quasi-Ohmic contact with N, N'-bis (naphthalen-1-yl)-N, N'-bis(phenyl) benzidine (NPB). The DI-SCLC results show a clear peak current along with a shift of the peak position as the field intensity varies, implying an Ohmic (or quasi-Ohmic) contact. A theoretical simulation of the SCLC also shows that ITO/$C_{60}$ forms an Ohmic contact with NPB. The Ohmic contact makes it possible to estimate the NPB hole mobility through the use of both DI-SCLC and trap-free SCLC analysis. This also contributes to a reduction in power consumption.

• Journal of Positioning, Navigation, and Timing
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• 제11권2호
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• pp.99-107
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• 2022

Urban Air Mobility (UAM) such as a drone taxi is one of the future transportations that have recently been attracting attention. Along with the construction of an urban terminal, an accurate landing system for UAM is also essential. However, in urban environments, reliable Global Navigation Satellite Systems (GNSS) signals cannot be received due to obstacles such as high-rise buildings which causes multipath and non-line of sight signal. Thus, the positioning result in urban environments from the GNSS signal is unreliable. Consequently, we propose the Ultra-Wideband (UWB) network to assist the soft landing of UAM on a vertiport. Since the positioning performance of UWB network depends on the layout of UWB anchors, it is necessary to optimize the layout of UWB anchors. In this paper, we propose a two-steps genetic algorithm that consists of binary genetic algorithm involved multi objectives fitness function and integer genetic algorithm involved robust solution searching fitness function in order to optimize taking into account Fresnel hole effects.

• Journal of Information Display
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• 제12권1호
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• pp.47-50
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• 2011

Highly stable amorphous indium.gallium.zinc-oxide (a-IGZO) thin-film transistors (TFTs) were fabricated with an etchstopper and via-hole structure. The TFTs exhibited 40 $cm^2$/V s field-effect mobility and a 0.21 V/dec gate voltage swing. Gate-bias stress induced a negligible threshold voltage shift (${\Delta}V_{th}$) at room temperature. The excellent stability is attribute to the via-hole and etch-stopper structure, in which, the source/drain metal contacts the active a-IGZO layer through two via holes (one on each side), resulting in minimized damage to the a-IGZO layer during the plasma etching of the source/drain metal. The comparison of the effects of the DC and AC stress on the performance of the TFTs at $60^{\circ}C$ showed that there was a smaller ${\Delta}V_{th}$ in the AC stress compared with the DC stress for the same effective stress time, indicating that the trappin of the carriers at the active layer-gate insulator interface was the dominant degradation mechanism.

• 한국산업정보학회논문지
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• 제10권2호
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• pp.76-81
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• 2005

본 연구에서는 차세대 디스플레이 소자로 각광을 받고 있는 유기발광 소자의 전기적인 특성을 해석적으로 접근하였다. 기본적인 OLED의 동작 메카니즘은 일함수(work function)가 낮은 음극(cathode) 전극으로부터 주입된 전자(electron)와 양극(anode) 전극으로 주입된 정공(hole)이 수송층을 지나 발광층으로 유입되어 여기상태(exciton state)를 거치며 재결합함으로써 발광되는 것으로 알려져 있다. 따라서 음극과 양극을 통해 들어오는 수송자(carrier)들이 원활한 전자-정공 쌍(electron - hole pair)을 이루기 위해 다층 박막 구조로 소자를 제작하여 높은 에너지 장벽을 완만하게 만들고 또한 박막의 두께를 조절하여 정공과 전자의 이동도 밸런스(balance)를 맞추어 수송자-전자와 정공-들이 수송층(CTL : carrier transport layer)을 통해 발광층(EML : emitting material layer)으로 주입을 용이하게 만든다 따라서 본 논문에서는 유기 발광소자의 최적의 발광특성을 얻기 위해서는 수치 해석을 통한 가장 높은 발광 효율을 가지게되는 박막의 두께를 예측하고 예측된 유기발광소자의 수치해석 값이 실제 제작된 소자의 특성 값과 일치하여 타당성이 있음을 증명하고자 한다.

• Macromolecular Research
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• 제10권2호
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• pp.75-79
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• 2002

Organic materials have considerable attention as active semiconductors for device applications such as thin-film transistors (TFTs) and diodes. Pentacene is a p-type organic semiconducting material investigated for TFTs. In this paper, we reported the morphological and electrical characteristics of pentacene TFT films. The pentacene transistors showed the mobility of 0.8 $\textrm{cm}^2$/Vs and the grains larger than 1 ${\mu}{\textrm}{m}$. Deep-level transient spectroscopy (DLTS) measurements were carried out on metal/insulator/organic semiconductor structure devices that had a depletion region at the insulator/organic-semiconductor interface. The duration of the capacitance transient in DLTS signals was several ten of seconds in the pentacene, which was longer than that of inorganic semiconductors such as Si. Based on the DLTS characteristics, the energy levels of hole and electron traps for the pentacene films were approximately 0.24, 1.08, and 0.31 eV above Ev, and 0.69 eV below Ec.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.98-100
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• 2008

A series of new channel materials using triisopropylsilylethynyl anthracene(TIPSAN) derivatives are synthesized by well known reaction. The TIPSAN derivatives exhibit an excellent field-effect mobility with hole mobility as high as 0.1 cm2V-1s-1 by solution-process and slip stack structure of core and end groups with short $\pi-\pi$ stacking distance of $3.525{\sim}3.485\;{\AA}$ by single crystal structures.