• Transactions on Electrical and Electronic Materials
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• 제7권1호
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• pp.21-25
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• 2006

In this study, liquid crystal (LC) aligning properties for homeotropic alignment on the $SiO_x$ thin film by electron beam evaporation method with electron beam system in accordance with the evaporation angles were investigated. Also, the control of pretilt angles homeotropic aligned LC on $SiO_x$ thin film as the function of the evaporation angles were studied. The uniform vertical LC alignment on the $SiO_x$ thin film surfaces with electron beam evaporation was achieved with all of the thin film angle conditions. It is considerated that the LC alignment on the $SiO_x$ thin film by electron beam evaporation is attributed to elastic interaction between LC molecules and micro-grooves at the $SiO_x$ thin film surface created by evaporation. The values of the pretilt angles according to the evaporation angle were from about $0.7^{\circ}$ to about $3.4^{\circ}$. The highest pretilt angles of about $3.4^{\circ}$ in aligned NLC on the $SiO_x$ thin film surfaces by electron beam evaporation were measured under the condition of $45^{\circ}$. Also, good LC alignment states on the treated $SiO_x$ thin film layer by electron beam evaporation were observed at annealing temperature of $250^{\circ}C$. Consequently, the high pretilt angle and the good thermal stability of LC alignment on the $SiO_x$ thin film by electron beam evaporation can be achieved.

• 폴리머
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• 제30권2호
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• pp.97-107
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• 2006

방향족 강직사슬 폴리이미드는 높은 주사슬 간의 인력으로 인해 유기용제에 용해되지 않고 상전이온도가 분해 온도보다 높아 응용분야에 많은 제한이 되고 있다. 방향족 폴리이미드의 가공성을 향상시키기 위해서 긴 곁사슬을 도입하면 가공성 향상뿐만 아니라 곁사슬과 주사슬 사이에 독특한 구조를 가지게 됨으로써 새로운 응용분야를 개척할 수가 있다. 본 논문에서는 여러 가지 형태의 곁사슬을 가지는 방향족 폴리이미드의 합성과 화학구조에 따른 물성변화에 대해 논의하고 또한 폴리이미드의 액정배향막, 감광재료, 교대 다층박막, 발광재료 등으로의 응용특성에 관해서도 조감한다.

• Transactions on Electrical and Electronic Materials
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• 제8권3호
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• pp.135-138
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• 2007

In this study, we investigated the electro-optical (EO) characteristic of fringe-field switching (FFS) mode cell by the two kinds of ultraviolet (UV) alignment method on the organic thin film (polyimide: PI). The suitable organic layers for FFS cell and the aligning capabilities of nematic liquid crystal (NLC) using the in-situ photoalignment method were studied; Disclination is observed after conventional photoalignment method for 1h, and in-situ photoalignment method for 1h. Monodomain alignment of the NLC can be observed via insitu photo alignment method for 2 h and 3 h. It is considered that NLC alignment is due to photo-depolymerization of the polymer with oblique non-polarized UV irradiation on PI surface. An unstable V-T curve of UV-aligned FFS-LCD with conventional photoalignment method can be achieved. However, a stable V-T curve of UV-aligned FFS-LCD with in-situ photoalignment method (1 h), and V-T curve of UV-aligned FFS-LCD with in-situ photo alignment method was much stable comparing with that of other UV-aligned FFSLCD's. As a result, more stable EO performance of UV-aligned FFS-LCD with in-situ photoalignment method for 3h is obtained than that of the other UV-aligned FFS-LCD's.

• 한국위성정보통신학회논문지
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• 제10권3호
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• pp.89-93
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• 2015

본 연구에서는 이온빔 처리된 $HfO_2$ 박막을 이용한 액정디스플레이의 프리틸트각을 제어함으로써, 작은 구동전압에서도 안정적으로 구동할 수 있는 디스플레이 소자에 응용할 수 있는 특성을 연구하였다. $HfO_2$ 박막의 원자 수준의 증착을 통해서 높은 유전율의 박막을 제조할 수 있었으며, 이는 저전력 구동을 위해서 필수적인 요소라고 생각한다. 또한 이러한 $HfO_2$ 박막의 액정배향성을 확인하여 균일한 액정배향을 통해서 디스플레이 소자로의 응용가능성을 확인하였다. 특히 $HfO_2$ 박막에서의 액정배향성에 대해서 액정배향의 대표적인 특성인 프리틸트각의 제어를 실험을 통해서 확인하였다. 실험결과 이온빔처리를 한 $HfO_2$ 박막에서의 액정배향의 특성을 접촉각특성을 대표화하여 정량화 할 수 있었다. 본 연구의 결과 액정의 배향성 확보 및 프리틸트각을 제어할 수 있는 고유전율 $HfO_2$ 박막의 제조가 가능한 것을 확인할 수 있었으며, 고유전율 특성에서 기인하는 저전력 구동의 가능성을 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1815-1817
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• 1999

In this paper, the generation of high pretilt angle in nematic liquid crystal (NLC) by dipping effect on three kinds of the rubbed polyimide (PI) surface was investigated. The generated pretilt angle of NLC increases due to dipping effect before rubbing treatment on two kinds of the rubbed PI surface with side chain. The generated pretit angle in NLC by using dipping effect after rubbing treatment on PI surface with short side chain is high compared to the PI surface with long side chain. The generated pretit angle of the positive type NLC $(\Delta{\varepsilon}>0)$ is higher as than that of the negative type NLC $({\Delta}{\varepsilon}<0)$ by using dipping effect before rubbing treatment on homeotropic layer. The generated pretilt angle of NLC is attributed to perpendicular component of permittivity ${\varepsilon}_{\perp}$ of NLC on rubbed PI surface.

• 한국응용과학기술학회지
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• 제15권4호
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• pp.21-25
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• 1998

Organic-based electroluminescent devices have attracted lots of interests because of their possible application as a large-area flat panel display. Polyimides have been used for photo-alignment in LCD(Liquid Crystal Display). However, the devices used in this study were fabricated with polyimide doped with N,N'-Diphenyl-N,N'-di(m-tolyl)-benzidine(TPD) (3, 10, 30wt%) for electroluminescent hole tranforting layer(EHTL). The photochemical and physical properties of EHTL was studied. The film thicknesses were reduced under illumination with UV light. Polyimide films doped with TPD(3wt%) was irradiated and the electrical properties of the films were studied.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.118-120
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• 2002

Electro-optical (EO) characteristics of the ion beam (IB) aligned twisted nematic (TN)-liquid crystal display (LCD) with oblique ion beam exposure on the diamond-like carbon (DLC) thin film surface were studied. An excellent voltage-transmittance (V-T) curve of the ion beam aligned IN-LCD was observed with oblique ion beam exposure on the DLC thin film surface for I min. Also, a faster response time for the ion beam aligned TN-LCD with oblique ion beam exposure on the DLC thin film surface for 1 min can be achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.637-640
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• 2009

The LCD based on Kerr effect is highly interesting because it uses an optically isotropic state with no need of alignment layer and it shows sub-millisecond response time. The problem of the device is that it requires very high operating voltage and the transmittance is relatively low compared with other LCDs that use nematic LC. In this work, we study on various electrode structures and driving method which can lower operating voltage.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 하계학술발표회
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• pp.120-121
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• 2003

아조벤젠 고분자는 광 정보저장 및 광 스위치 소자 등의 응용가능성 때문에 많은 연구가 진행되어왔다. 이것은 바로 아조 분자가 가지고 있는 두 이성체 간의 광 이성화 과정에 의한 아조 분자의 정렬에 의한 광 유도 anisotropy가 생기는 특성과 더불어 아조 분자의 이동에 의한 표면 부조가 형성됨이 보고된 이후에 광 정보 저장은 물론 액정의 배향이나 phase mask로의 응용, 특히 photonic band gap(PBG) 효과를 기대 할 수 있는 주기구조 형성에의 응용성 때문에 더욱 관심이 집중되고 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.252.2-252.2
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• 2013

ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.