• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.420-421
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• 2007

본 연구에서는 유기물 발광 다이오드(OLED)의 효율을 향상시키기 위하여 버퍼층 역할을 하는 PEDOT:PSS (poly(3,4-ethylenedioxythiophene) : poly styrene sulfonate)의 공정조건을 확립하고 두께에 따른 전기적 광학적 특성을 조사하였다. PEDOT:PSS는 spin coating 방법으로 증착을 하였으며, 흘효과측정을 통하여 ITO기판과 유기버퍼층이 코팅된 기판의 전하운반체의 이동도와 전류-전압 특성을 조사하였다. 그리고 UV-vis spectrometer를 이용하여 광투과도, 굴절률, 밴드갭을 측정하였고 SEM을 이용하여 시료의 표면도 관찰하였다. 유기물 버퍼층(PEDOT:PSS)의 두께가 얇을수록 정공의 이동도가 향상됨을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.400-400
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• 2007

In this study, we investigated liquid crystal (LC) alignment with ion beam (IB) that non contact alignment technique on polyimide and electro-optical characteristics of twisted nematic (TN)-liquid crystal display (LCD) on the polyimide under various ion beam angles. In this experiment, polyimide layer was coated on glass by spin-coating and Voltage-transmittance(VT) and response time characteristics of the TN cell were measured by a LCD evaluation system. The good characteristics of the nematic liquid crystal (NLC) alignment with the ion beam exposured polyimide surface was observed. In addition, it can be achieved the good EO properties, and residual DC property of the ion beam aligned TN cell on polyimide surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.394-394
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• 2007

Transparent conductive films can serve as a critical component in displays, solar cells, lasers, optical communication devices, and solid state lighting. Carbon nanotube (CNT) based transparent conductive films are fabricated on glass and polymer substrates. CNTs typically exist in form of quasi-crystalline bundles or highly entangled bundles containing tens of individual nanotubes. To achieve full potential, CNTs must be dispersed in a solvent or other organic media. CNTs are acid treated with nitric acid then the stable dispersion of CNTs in polar solvent such as alcohols, DMF, etc. is achieved by sonication. The solubility of CNTs correlates well with the area ratio of the D and G bands from Raman spectrum. Thin films are formed from well dispersed CNT solutions using spray coating method. CNT thin films exhibit a sheet resistance ($R_s$) of nearby $10^3\;{\Omega}/sq$ with a transmittance of around 80% on the visible light range, which is attributed by excellent dispersion and interaction among CNTs, solvents and polymeric binders.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.369-369
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• 2007

ZnO film has been investigated during several decades because it has excellent optical property like a transmittance among the range of visible light for using transparent conducting oxide (TCO) films. But ZnO film has not enough conductivity for applying to TCO devices. Therefore we synthesized platinum nanoparticles and they incorporated into ZnO due to improve the electrical property of ZnO film by sol-gel synthesis method. Also, we fabricated photosensitive ZnO thin film containing Pt nanoparticles by sol-gel process and spin-coating for using photochemical solution deposition. Photosensitive ZnO film could carry out the direct-pattern which allow the etching process to be convenient. The optical and electrical properties of ZnO film with or without various atomic percent of Pt nanoparticles annealed at various temperatures were investigated by using UV-Vis spectroscopy and 4-point probe method, respectively. We characterized the ZnO thin film containing Pt nanoparticles using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.85-88
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• 2012

DSCs are based on a dye-adsorbed porous $TiO_2$ layer as a photo electrode [1]. Under the illumination, dye molecules are excited and electrons are produced. The injected electrons in the conduction band of $TiO_2$ may recombine with the electrolyte. To obtain high performance DSCs, it is essential to retard the recombination. The charge recombination can be reduced by forming core-shell structure. In this work, we investigated the core-shell structure with $Al_2O_3$ and MgO coating layer on the porous $TiO_2$ layer. We confirmed the photovoltaic properties by I-V characteristics. The current and the efficiency was improved. In addition to, Through decrease in the width of EIS arc, which is the sum of the interfacial charge transfer resistances of both electrodes, we can be indicated that the block effect.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.6
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• pp.419-425
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• 2001

A dense pellicular solid matrix has been fabricated by coating 4% agarose gel on to dense zironia-silica(ZS) spheres by watr-in-oil emulsification . The agarose evenly laminated the ZS bead to a depth of 30㎛, and the resultin gpellicular assembly was characterised by densities up to 2.39g/mL and a mean particle dimeter of 136 ㎛. In comparative fluidisation tests, the pellicular solid phase exhibited a two-fold greater flow velocity than commercial benchmark ad-sorbents necessary to achieve common values of bed expansion. Furthermore, the perlicular parti-cles were characterised by improved qualities of chromatographic behaviour, particularly with re-spect to a three-fold increase in the apparent effective diffusivity of lysozyme within a pellicular assembly modified with Cibacron Blue 3GA. The properties of rapid protein adsorption/desorp-tion were attributed to the physical design and pellicular deployment of the reactive surface in the solid phase. When combined with enhanced feedstock throughput, such practical advantages recommend the pellicular assembly as a base matrix for the selective recovery of protein products from complex, particulate feedstocks(whole fermentation broths, cell disruptates and biological extracts).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.392-393
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• 2006

This paper describes the fabrication of SiCN microstructures for super-high temperature MEMS using photopolymerization of pre-ceramic polymer. In this work. polysilazane liquide as a precursor was deposited on Si wafers by spin coating. microstructured and solidificated by UV lithography. and removed from the substrate. The resulting solid polymer microstructures were cross-linked under HIP process and pyrolyzed to form a ceramic of withstanding over $1400^{\circ}C$. Finally, the fabricated SiCN microstructures were annealed at $1400^{\circ}C$ in a nitrogen atmosphere. Mechanical characteristics of the SiCN microstructure with different fabrication process conditions were evaluated. The elastic modules. hardness and tensile strength of the SiC microstructure implemented under optimum process conditions are 94.5 GPa, 10.5 GPa and 11.7 N/min, respectively. Consequently, the SiCN microstructure proposed in this work is very suitable for super-high temperature MEMS application due to very simple fabrication process and the potential possiblity of sophisticated multlayer or 3D microstructures as well as its good mechanical properties.

• Macromolecular Research
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• v.16 no.4
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• pp.373-378
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• 2008

A simple chemical fixation method for the fabrication of layer-by-layer (LbL) polyelectrolyte multilayer (PEM) has been developed to create a large area, highly uniform film for various applications. PEM of weak poly-electrolytes, i.e., polyallylamine hydrogen chloride (PAH) and poly(acrylic acid)(PAA), was assembled on polymer substrates such as poly(methyl methacrylate)(PMMA) and polycarbonate (PC). In the case of a weak polyelectrolyte, the fabricated thin film thickness of the polyelectrolyte multilayers was strongly dependent on the pH of the processing solution, which enabled the film thickness or optical properties to be controlled. On the other hand, the environmental stability for device application was poor. In this study, we utilized the chemical fixation method using glutaraldehyde (GA)-amine reaction in order to stabilize the polyelectrolyte multilayers. By simple treatment of GA on the PEM film, the inherent morphology was fixed and the adhesion and mechanical strength were improved. Both surface tension and FT-IR measurements supported the chemical cross-linking reaction. The surface property of the polyelectrolyte films was altered and converted from hydrophilic to hydrophobic by chemical modification. The possible application to antireflection coating on PMMA and PC was demonstrated.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.235-235
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• 2010

장비와 cutting기술의 발전으로, 높은 효율성을 지닌 어려운 작업 재료들의 고속 건조 가공기술은 생산성, 가격 인하 그리고 환경적인 관점에서 중요성이 증가하게 되었다. AlTiN에서 Si의 첨가는 40GPa이상의 고경도와 1000도 이상의 산화온도를 지닌 나노혼합물 코팅을 형성시키는 것으로 알려졌다. 또한 Si가 아닌 다른 soft 물질을 첨가하고 3성분 이상의 다성분계 박막을 형성하는 실험을 하여, 물성이 어떻게 달라지는지 확인하였다. 특히, 나노 코팅층 형성이 매우 어려운 Al-Ti-N 합금계에서 Si, Cu 첨가의 영향 및 이러한 코팅층 형성을 단일합금을 이용하여 행하였을 때, 장점을 확인하였다. 이러한 연구를 위하여 Ti-Al의 합금 조성을 경도가 가장 우수한 것으로 알려진 50 : 50으로 하여 타겟을 만들고 증착시켜 기초실험을 진행하여 물성조건을 확인하고 이에 근거하여 실험을 진행하였다. 또한 3 원계 합금으로서 Cu, Si를 첨가한 연구를 수행하였다. 또한, 최적 조성의 합금 조성을 확인한 후, 단일 합금 타겟을 제조하였으며 이를 이용하여 형성된 코팅층과 다성분계 타겟을 이용한 박막의 물성을 비교하였다. 증착된 박막의 분석장비로는 SEM, EDS, XRD 와 AFM등을 이용하였으며, 막의 조직과 증착 두께, 조도 그리고 경도를 확인하고 막의 물성 특성이 향상됨을 입증하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.318.1-318.1
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• 2013

Nowadays Cu2ZnSnS4 (CZTS) solar cell is attracting a lot of attention as a strong alternative to CIGS solar cell due to nontoxic and inexpensive constituent elements of CZTS. From various processes for the fabrication of CZTS solar cell, solution-based deposition of CZTS thin films is well-known non-vacuum process and many researchers are focusing on this method because of large-area deposition, high-throughput, and efficient material usage. Typically the solution-based process consists of two steps, coating of precursor solution and annealing of the precursor thin films. Unlike vacuum-based deposition, precursor solution contains unnecessary elements except Cu, Zn, Sn, and S in order to form high quality precursor thin films, and thus the precise control of precursor thin film preparation is essential for achieving high efficient CZTS solar cells. In this work, we have investigated the effect of preparation condition of CZTS precursor thin films on the performance of CZTS solar cells. The composition of CZTS precursor solution was controlled for obtaining optimized chemical composition of CZTS absorber layers for high-efficiency solar cells. Pre-annealing process of the CZTS precursor thin films was also investigated to confirm the effect of thermal treatment on chemical composition and carbon residues of CZTS absorber layers. The change of the morphology of CZTS precursor thin film by the preparation condition was also observed.