• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1438-1439
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• 2011

In this paper, we studied effects on the efficiency, according to thickness of the electron injection layer(EIL) for improving efficiency of Organic Light Emitting Diodes(OLEDs). For the first time, after confirming the optimum thickness of the EIL material $Cs_2CO_3$, we designed OLED devices having a structure of ITO/TPD/$Alq_3/Cs_2CO_3$/Al. And we manufactured devices applying for the optimum thickness of the material in the simulation with thermal evaporating method. And we investigated how the EIL material $Cs_2CO_3$ effects on efficiency of OLEDs in the EIL. As the result, because the EIL material $Cs_2CO_3$ reduces energy potential barrier of the EIL, it facilitated the electron transfer. And, as blocking the hole transfer contributes to an increased recombination, we confirmed that the efficiency of OLEDs increased. And compared to the device without using the EIL material, the device using thickness 1.0 nm of $Cs_2CO_3$ in the EIL shows the excellent efficiency. Therefore, we confirmed that the luminance and the external quantum efficiency increase about 600% and 500% respectively.

• Journal of Photoscience
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• 제10권1호
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• pp.121-126
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• 2003

Irradiation of an acetonitrile solution containing dimethylbis(4-vinylphenylmethyl)silane 1a in the presence of 9,10-dicyanoanthracene leads to formation of the intramolecular photocycloadduct, 2-sila-cyclobuta[2.3]cyclophane(2a). In contrast, prolonged irradiation gave insoluble polymeric material. The photocycloreversion of 2a occurs efficiently (quantum yields exceeds unity) by use of redox-type photosensitization in the presence of magnesium perchlorate. The transient absorption spectra generated by pulse radiolysis and gamma-radiolysis show that the radical cation species generated from 1a is different from that arising from 2a.

• 대한화학회지
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• 제34권2호
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• pp.159-164
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• 1990

광학활성인 [Co(EDDS)]- (EDDS = ethylenediaminedisuccinate) 착물의 절대구조는 옥탄트규칙과 분광학적인 자료에 따라 Λ-형임을 확인하였고, 절대구조가 확인된 Λ$-[Co(EDDS)]-$ 와 라세미체-$[Co(en)_3]^{3+}$간의 입체선택적 이온회합에서는 Λ$-[Co(EDDS)]-$ 와 Δ$-[Co(en)_3]^{3+}$간의 이온회합이 우선적으로 일어남을 조사하였다. 아울러 Λ$-[Co(EDDS)]-$ 와 라세미체$-[Co(en)_3]^{2+}$간의 입체선택적 전자전달반응에서는 착물간의 입체선택적 이온회합에 따라 Δ$[Co(en)_3]^{3+}$가 14% e.e (e.e = enantiomeric excess)로 생성되었다.

• Korean Chemical Engineering Research
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• 제52권2호
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• pp.209-213
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• 2014

A graft copolymer of poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom transfer radical polymerization (ATRP) and used as a structure-directing agent to prepare $Al@Fe_2O_3$ core-shell nanocomposites through a sol-gel process. The amphiphilic property of PVC-g-POEM allows for good dispersion of Al particles and leads to specific interaction with iron ethoxide, a precursor of $Fe_2O_3$. Secondary bonding interaction in the sol-gel composites was characterized by Fourier transform-infrared (FT-IR) spectroscopy. The well-organized morphology of $Al@Fe_2O_3$ core-shell nanocomposites was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) were used to analyze the elemental composition and crystallization structure of the composites.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권6호
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• pp.505-509
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• 2005

For the purpose of developing a direct label-free electrochemical detection system, we have systematically investigated the electrochemical signatures of each step in the preparation procedure, from a bare gold electrode to the hybridization of label-free complementary DNA, for the streptavidin-modified electrode. For the purpose of this investigation, we obtained the following pertinent data; cyclic voltammogram measurements, electrochemical impedance spectra and square wave voltammogram measurements, in $Fe(CN)_6^{3-}/Fe(CN)_6^{4-}$ solution (which was utilized as the electron transfer redox mediator). The oligonucleotide molecules on the streptavidin-modified electrodes exhibited intrinsic redox activity in the ferrocyanide-mediated electrochemical measurements. Furthermore, the investigation of electrochemical electron transfer, according to the sequence of oligonucleotide molecules, was also undertaken. This work demonstrates that direct label-free oligonucleotide electrical recognition, based on biofunctional streptavidin-modified gold electrodes, could lead to the development of a new biosensor protocol for the expansion of rapid, cost-effective detection systems.

• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.52-57
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• 2016

Nanoporous-layer-covered TiO₂ nanotube arrays (Type II TNTs) were fabricated by two-step electrochemical anodization. For comparison, conventional TiO₂ nanotube arrays (Type I TNTs) were also prepared by one-step electrochemical anodization. Types I and II TNTs were detached by selective etching and then transferred successfully to a transparent F-doped SnO₂ (FTO) substrate by a sol-gel process. Both FTO/Types I and II TNTs allowed front side illumination to exhibit incident photon-to-current efficiencies (IPCEs) in the long wavelength region of 300 to 750 nm without the absorption of light by the iodine-containing electrolyte. The Type II TNT exhibited longer electron lifetime and faster charge transfer than the Type I TNT because of its relatively fewer defect states. These beneficial effects lead to a high overall energy conversion efficiency (5.32 %) of the resulting dye-sensitized solar cell.

• 한국전기전자재료학회논문지
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• 제19권3호
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• pp.246-249
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• 2006

We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. We determined the time dependence on resonant frequency shift during self-assembly process and observed the morphology of self-assembled monolayers by STM and investigated the electrochemical behavior of SAMs by cyclic voltammetry. Electrochemical deposition of viologen was investigated using electrochemical quartz crystal microbalance(EQCM). The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redok reactions. The total frequency change was about 9.5 Hz, and 7.1 Hz. From the data, we could know the mass change was about 10.16 ng and 7.60 ng, respectively. Finally, the EQCM has been employed to monitor the electrochemically induced adsorption of self-assembled monolayers on Au surfaces.

• Applied Microscopy
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• 제19권2호
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• pp.43-58
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• 1989

To investigate the effects of hexavalent chromium on mitochondrial respiration of rat kidney, various hexavalent chromium concentrations were treated, then respiration and electron transfer enzyme activities were measured. Ultrastructural changes at state IV respiration of mitochondria were also observed. Then, to investigate protective role against hexavalent chromium in the body, low-molecular-weight, chromium-binding substances (LMCr) were purified from livers of rabbits 2hr after intravenously administrated with sodium dichromate at a dose of 74mg per kg body weight. And then, respiration rates of mitochondria treated with LMCr, hexavalent chromium containing 0.7mM chromium were measured. Hexavalent chromium decreased state IV respiration rates and electron transfer enzyme activities of mitochondria, and increased labile membrane and swelling. And partial inhibitions of condensed to orthodox conformational change were observed. Respiration rates of mitochondria treated with LMCr containing 0.7mM chromium did not differ from that of the non-treated mitochondria. But respiration rates of 0.7mM hexavalent chromium-treated mitochondria decreased by 42%, compared to non-treated mitochondria. These results suggest that LMCr may play an important role in detoxification of toxic hexavalent chromium.

• 한국수정란이식학회지
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• 제15권1호
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• pp.15-21
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• 2000

These studies were undertaken to evaluate morphological normality and development competence in vitro of hyman oocytes following vitrificatioin using ethylene glycol and electron microscopic grid. Human immature oocytes retrieved from natural and stimulated cycles was vitrified at 0 or 48 h and 0, 8 to 15 or 24 to 28 h after maturation culture, respectively. In oocytes retrieved from unstimulated cycle, no signifciant differences were found in morphological normality (56 to 63%) and fertilization (31 to 37%) rates between the times of vitrification. In stimulated patients, however, more oocytes were morphologically normal when vitrified at 24 to 28 h than when vitrified at 0 or 8 to 15 h after maturation culture. Regardlesss of the hormonal stimulation, high cleavage rates(83 to 100%) were obtained in all treatment groups but did not differ significantly. Twenty to 43% of cleaved oocytes developed to the blastocyst stage at 6 days after IVF. These results suggest that vitrified oocytes from unstimulated and stimulated cycles could develop to the blastocyst stage, regardless of the stages of vitrification.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.473-473
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• 2011

In recent years, organic thin film transistors OTFTs based on conductive-conjugated molecules have received significant attention. We report a fabrication of organic single crystal nanowires that made on Si substrates by liquid bridge-mediated nanotransfer molding (LB-nTM) with polyurethane acrylate (PUA) mold. LB-nTM is based on the direct transfer of various materials from a stamp to a substrate via a liquid bridge between them. In liquid bridge-transfer process, the liquid layer serves as an adhesion layer to provide good conformal contact and form covalent bonding between the organic single crystal nanowire and the Si substrate. Pentacene is the most promising organic semiconductors. However pentacene has insolubility in organic solvents so pentacene OTFTs can be achieved with vacuum evaporation system. However 6, 13-bis (triisopropylsilylethynyl) (TIPS) pentacene has high solubility in organic solvent that reported by Anthony et al. Furthermore, the substituted rings in TIPS-pentacene interrupt the herringbone packing, which leads to cofacial ${\pi}-{\pi}$ stacking. The patterned TIPS-Pentacene single crystal nanowires have been investigated by Atomic force microscopy (AFM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and electrical properties.