• 공업화학
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• 제29권4호
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• pp.425-431
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• 2018

UV 및 블루라이트를 차단하는 세륨 옥사이드 나노 입자와 다공성 실리카와의 복합입자를 건식 코팅 공정을 통해 제조하였다. 실리카와 세륨 옥사이드 간 혼합 비율과 메카노 퓨전 장치의 챔버 회전속도 등의 제조 조건을 달리하여 여러 복합입자를 만든 후, 입자 표면 형태를 SEM으로 관측 비교하고 XRF을 통해 복합입자의 조성을 분석하였다. 세륨 옥사이드를 실리카와 함께 복합입자로 만들어 물에 분산시키면 현탁 용액의 투명도가 높아지고 분산 안정성이 향상되었다. 또한 파우더의 유동성과 발림성이 개선되었다. 본 연구를 통해 세륨 옥사이드/실리카 복합입자가 자외선 및 블루라이트를 차단하는 기능성 화장품 소재로 사용 가능함을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.127-127
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• 2011

We investigate the transparent TFTs using a transparent ZnSnO3 (ZTO)/Ag/ZTO multilayer electrode as S/D electrodes with low resistivity of $3.24{\times}10^{-5}$ ohm-cm, and high transparency of 86.29% in ZTO based TFTs. The Transparent TFTs (TTFTs) are prepared on glass substrate coated 100 nm of ITO thin film. On atomic layer deposited $Al_2\;O_3$, 50 nm ZTO layer is deposited by RF magnetron sputtering through a shadow mask for channel layer using ZTO target with 1 : 1 molar ratio of ZnO : $SnO_2$. The power of 100W, the working pressure of 2mTorr, and the gas flow of Ar 20 sccm during the ZTO deposition. After channel layer deposition, a ZTO (35 nm)/Ag (12 nm)/ZTO(35 nm) multilayer is deposited by DC/RF magnetron sputtering to form transparent S/D electrodes which are patterned through the shadow mask. Devices are annealed in air at 300$^{\circ}C$ for 30 min following ZTO deposition. Using UV/Visible spectrometer, the optical transmittances of the TTFT using ZTO/Ag/ ZTO multilayer electrodes are compared with TFT using Mo electrode. The structural properties of ZTO based TTFT with ZTO/Ag/ZTO multilayer electrodes are analyzed by high resolution transmission electron microscopy (HREM) and X-ray photoelectron spectroscopy (XPS). The transfer and output characterization of ZTO TTFTs are examined by a customized probe station with HP4145B system in are.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.106-106
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• 2011

Recently, zinc oxide (ZnO) thin films have attracted great attention as a promising candidate for various electronic applications such as transparent electrodes, thin film transistors, and optoelectronic devices. ZnO thin films have a wide band gap energy of 3.37 eV and transparency in visible region. Moreover, ZnO thin films can be deposited in a poly-crystalline form even at room temperature, extending the choice of substrates including even plastics. Therefore, it is possible to realize thin film transistors by using ZnO thin films as the active channel layer. In this work, we investigated influence of oxygen partial pressure on ZnO thin films and fabricated ZnO-based thin film transistors. ZnO thin films were deposited on glass substrates by using a pulsed laser deposition technique in various oxygen partial pressures from 20 to 100 mTorr at room temperature. X-ray diffraction (XRD), transmission line method (TLM), and UV-Vis spectroscopy were employed to study the structural, electrical, and optical properties of the ZnO thin films. As a result, 80 mTorr was optimal condition for active layer of thin film transistors, since the active layer of thin film transistors needs high resistivity to achieve low off-current and high on-off ratio. The fabricated ZnO-based thin film transistors operated in the enhancement mode with high field effect mobility and low threshold voltage.

• 한국식품영양과학회지
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• 제31권3호
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• pp.475-481
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• 2002

분해성 천연 고분자인 PHB와 chitosan을 블렌드하여 필름을 제조한뒤 필름의 결정특성 및 물리적 성질을 측정한 결과 PHB/chitosan 필름의 X선 회절도 측정에서 상대 결정화도는 chitosan의 함량이 증가할수록 낮아졌으며 FT-lR 측정에서는 chitosan 비율이 증가할수록 PHB의 carbonyl기 의 피크가 작아졌다. DSC측정에 의한 필름의 열적 특성에서는chitosan의 첨가로 인해 열안정성과 결정성이 낮아지는 경향을 보였다. 시차주사현미경을 이용하여 관찰한 필름의 표면상태에서는 chitosan의 비율이 증가할수록 입자크기가 감소하는 것으로 나타났다. 필름의 물성은 PHB에 대한 chitosan의 함량이 증가할수록 인장강도와 신장률이 증가하여 chitosan 첨가로 인해 필름의 물성이 향상된 것을 알 수 있었다. PHB/chitosan필름의 색도 측정 결과 PHB에 chitosan의 함량이 증가할수록 L값과 b값은 낮아지고 필름의 투명도는 높아졌다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.380-380
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• 2010

Currently, organic light-emitting diodes (OLEDs) have been proven of their readiness for commercialization in terms of lifetime and efficiency. In accordance with emerging new technologies, enhancement of light efficiency and extension of application fields are required. Particularly inverted structures, in which electron injection occurs at bottom and hole injection on top, show crucial advantages due to their easy integration with Si-based driving circuits for active matrix OLED as well as large open area for brighter illumination. In order to get better performance and process reliability, usually a proper buffer layer for carrier injection is needed. In inverted top emission OLED, the buffer layer should protect underlying organic materials against destructive particles during the electrode deposition, in addition to increasing their efficiency by reducing carrier injection barrier. For hole injection layers, there are several requirements for the buffer layer, such as high transparency, high work function, and reasonable electrical conductivity. As a buffer material, a few kinds of transition metal oxides for inverted OLED applications have been successfully utilized aiming at efficient hole injection properties. Among them, we chose 2 nm of $WO_3$ between NPB [N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] and Au (or Al) films. The interfacial energy-level alignment and chemical reaction as a function of film coverage have been measured by using in-situ ultraviolet and X-ray photoelectron spectroscopy. It turned out that the $WO_3$ interlayer substantially reduces the hole injection barrier irrespective of the kind of electrode metals. It also avoids direct chemical interaction between NPB and metal atoms. This observation clearly validates the use of $WO_3$ interlayer as hole injection for inverted OLED applications.

• 한국재료학회지
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• 제18권1호
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• pp.32-37
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• 2008

The electrical, optical, structural and surface properties of an indium tin oxide (ITO) film grown on a flexible PET substrate using a specially designed roll-to-roll (R2R) sputtering system as a function of the DC power, $Ar/O_2$ flow ratio, and rolling speed is reported. It was observed that both the electrical and optical properties of the ITO film on the PET substrate were critically dependent on the $Ar/O_2$ flow ratio. In addition, x-ray diffraction examination results showed that the structure of the ITO film on the PET substrate was an amorphous structure regardless of the DC power and the $Ar/O_2$ flow ratio due to a low substrate temperature, which was maintained constant by a main cooling drum. Under optimized conditions, ITO film with resistivity of $6.44{\times}10^{-4}{\Omega}-cm$ and transparency of 86% were obtained, even when prepared at room temperature. Furthermore, bending test results exhibited that R2R-grown ITO film had good flexibility which would be applicable to flexible displays and solar cells.

• 한국염색가공학회지
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• 제31권3호
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• pp.165-176
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• 2019

Polyurethane-ureas(PUUs) were prepared from 4,4'-methylenebis(cyclohexyl isocyanate) and various diols including isosorbide. Isosorbide is starch-derived monomer that exhibit a wide range of glass transition temperature and are therefore able to be used in many applications. PUU was synthesized by a pre-polymer polymerization using a catalyst. Successful synthesis of the PUU was characterized by fourier transform-infrared spectroscopy. Thermal properties were determined by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. It was found that by tuning isosorbide content in the resin, their glass transition temperature(Tg) slightly decreased. Physical properties were also determined by tensile strength and X-ray diffraction. There is no significant differences between petroleum-derived diol and isosorbide in XRD analysis. Moreover, their physical and optical properties were determined. The result showed that the poly(tetramethylene ether glycol)/isosorbide-based PUU exhibited enhanced tensile strength, transmittance, transparency and biodegradability compared to the existing diols. After 11 weeks composting, the biodegradability of blends increased in ISB-PUU. The morphology of the fractured surface of blend films were investigated by scanning electron microscopy.

• 한국재료학회지
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• 제29권5호
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• pp.311-316
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• 2019

Transparent conducting electrodes are essential components in various optoelectrical devices. Although indium tin oxide thin films have been widely used for transparent conducting electrodes, silver nanowire network is a promising alternative to indium tin oxide thin films owing to its lower processing cost and greater suitability for flexible device application. In order to widen the application of silver nanowire network, the electrical conductance has to be improved while maintaining high optical transparency. In this study, we report the enhancement of the electrical conductance of silver nanowire network transparent electrodes by copper electrodeposition on the silver nanowire networks. The electrodeposited copper lowered the sheet resistance of the silver nanowire networks from $21.9{\Omega}{\square}$ to $12.6{\Omega}{\square}$. We perform detailed X-ray diffraction analysis revealing the effect of the amount of electrodeposited copper-shell on the sheet resistance of the core-shell(silver/copper) nanowire network transparent electrodes. From the relationship between the cross-sectional area of the copper-shell and the sheet resistance of the transparent electrodes, we deduce the electrical resistivity of electrodeposited copper to be approximately 4.5 times that of copper bulk.

• 한국응용과학기술학회지
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• 제35권3호
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• pp.595-605
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• 2018

최근 우수한 유연성과 화학적 안정성 등을 가진 고분자 수지와 우수한 기계적 성질 등을 나타내는 무기 재료로 이루어진 나노 복합 시스템으로써 유-무기 하이브리드 코팅 필름에 관한 연구가 활발히 진행되고 있다. 아크릴레이트 단량체로써 사용된 o-phenylphenoxyethyl acrylate (OPPEA)는 1.576의 높은 굴절률을 나타내고, Bisphenol A ethoxylate diacrylate (BAEDA)는 굴절률은 낮지만 경화된 고분자의 경도를 향상시킨다. 또한, 무기 소재로써 사용된 지르코니아는 산화지르코늄으로써 우수한 내구성과 광학특성 등을 나타낸다. 본 연구에서는 광학 특성을 향상시키기 위한 목적으로 아크릴레이트 단량체 중 BAEDA의 함량을 조절하여 필름을 제조한 뒤 연필 경도계와 아베굴절계를 이용하여 광학 특성 변화를 확인하였고, UV-vis spectrophotometer을 이용해 투과도를 비교하여 최적의 조건을 확립하였다. 그리고 실란 커플링제인 ${\gamma}$-methacryloxypropyltrimethoxysilane (MPS)를 사용하여 지르코니아를 소수화 처리하여 아크릴레이트 단량체에 대한 분산성을 향상시키고, 개질 전후의 물에 대한 분산성 변화를 조사하여 물에 대한 친화력이 감소하였음을 확인하였고, FT-IR ATR spectrophotometer를 통해 MPS에 의해 도입된 $1716cm^{-1}$에서의 에스터 C=O 결합 peak의 존재를 통해 MPS에 의한 지르코니아 표면의 개질 반응이 진행되었음을 확인하였다. 또한, 지르코니아의 표면에 도입된 규소 원자의 존재는 X 선 형광법을 이용하여 확인하였다. 그리고 화학적으로 개질된 지르코니아를 아크릴레이트 단량체에 도입하여 광경화 필름을 제조하였을 때, 굴절률은 아크릴레이트 자체 필름보다 1.2% 향상되었음을 확인하였고, SEM/EDS mapping 분석을 통해 PET 필름에 코팅된 개질 후 지르코니아가 아크릴레이트 코팅층에 균일하게 분포되어 있음을 알 수 있었다.

• 한국재료학회지
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• 제22권2호
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• pp.61-65
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• 2012

A $Li_2O-2SiO_2$ ($LS_2$) glass was investigated as a lithium-ion conducting oxide glass, which is applicable to a fast ionic conductor even at low temperature due to its high mechanical strength and chemical stability. The $Li_2O-2SiO_2$ glass is likely to be broken into small pieces when quenched; thus, it is difficult to fabricate a specifically sized sample. The production of properly sized glass samples is necessary for device applications. In this study, we applied spark plasma sintering (SPS) to fabricate $LS_2$ glass samples which have a particular size as well as high transparency. The sintered samples, $15mm\phi{\times}2mmT$ in size, ($LS_2$-s) were produced by SPS between $480^{\circ}C$ and $500^{\circ}C$ at 45MPa for 3~5mim, after which the thermal and dielectric properties of the $LS_2$-s samples were compared with those of quenched glass ($LS_2$-q) samples. Thermal behavior, crystalline structure, and electrical conductivity of both samples were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and an impedance/gain-phase analyzer, respectively. The results showed that the $LS_2$-s had an amorphous structure, like the $LS_2$-q sample, and that both samples took on the lithium disilicate structure after the heat treatment at $800^{\circ}C$. We observed similar dielectric peaks in both of the samples between room temperature and $700^{\circ}C$. The DC activation energies of the $LS_2$-q and $LS_2$-s samples were $0.48{\pm}0.05eV$ and $0.66{\pm}0.04eV$, while the AC activation energies were $0.48{\pm}0.05eV$ and $0.68{\pm}0.04eV$, respectively.