• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.457-458
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• 2006

Transparent metal cathodes using Ca/Ag, Ba/Ag double layers have been fabricated to investigate its optical transmission. The transmission spectra show that Ca/Ag and Ba/Ag double layers result in higher transmittance compared to Ag single layer. The Ba/Ag double layer shows over 80% transmittance at 400 nm and 70% at 700 nm. The electroluminescence efficiency of fluorescent TEOLED using Ba/Ag transparent metal cathode was 10 ~ 15 cd/A.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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• pp.1-11
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• 2014

Flexible transparent conductive electrodes (TCEs) have recently attracted a great deal of attention owing to rapid advances in flexible electronic devices, such as flexible displays, flexible photovoltanics, and e-papers. As the performance and reliability of flexible electronics are critically affected by the quality of TCE films, it is imperative to develop TCE films with low resistivity and high transparency as well as high flexibility. Indium tin oxide (ITO) has been the most dominant transparent conducting material due to its high optical transparency and electrical conductivity. However, ITO is susceptible to cracking and delamination when it is bent or deformed. Therefore, various types of flexible TCEs, such as carbon nanotube, conducting polymers, graphene, metal mesh, Ag nanowires (NWs), and metal mesh have been extensively investigated. Among several options to replace ITO film, Ag NWs and metal mesh have been suggested as the promising candidate for flexible TCEs. In this paper, we focused on Ag NWs and metal mesh, and summarized the current development status of Ag NWs and metal mesh. The several critical issues such as high contact resistance and haze are discussed, and newly developed technologies to resolve these issues are also presented. In particular, the flexibility and durability of Ag NWs and metal mesh was compared with ITO electrode.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.43-48
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• 2015

Silver nanowire (AgNW) is a material that is increasingly being used for transparent electrodes, as a substitute for indium tin oxide (ITO), owing to its flexibility, high transmittance to sheet resistance ratio, and simple production process. This study involves manufacturing large-area organic photovoltaic cells (OPVs) deposited on AgNW electrodes. We compared the efficiency of OPVs with ITO and AgNW electrodes. The results verified that an OPV with an AgNW electrode performed better than that with an ITO electrode. Furthermore, by using the knife coating method, we successfully fabricated large-area OPVs without the loss of efficiency. Use of AgNW instead of ITO demonstrated that an OPV could be produced on various substrates by the solution process method, dropping the productions costs significantly. Additionally, by using the knife coating method, the process time and amount of wasted solution are reduced. This leads to an increase in the efficient fabrication of the OPV.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.609-614
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• 2017

The proposed stretchable transparent electrodes based on silver nanowires (AgNWs) were prepared on a polyurethane (PU) substrate. In order toavoid the surface roughness caused by the silver nanowires, a titanium oxide ($TiO_2$) buffer layer was addedby coating and heating the organometallic sol-gel solution. The fabricated stretchable electrodes showedan electrical sheet resistance of $24{\Omega}sq^{-1}$, 78% transmittance at 550 nm, and an average surface roughness below 5 nm. Furthermore, the AgNW-based electrode maintained its initial electrical resistance under 130% strain testing conditions, without the assistance of additional conductive polymer layers. In this paper, the critical role of the $TiO_2$ buffer layer between the AgNW network and the PU substrate has been discussed.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.79-81
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• 2013

A novel method of fabricating polythiophene-gold nanoparticle composite film electrodes for photoelectric conversion is demonstrated. The method includes electrodeposition of gold and electropolymerization of 2,2'-bithiophene onto an indium-tin-oxide (ITO) electrode. First, electrodeposition of gold onto the ITO electrode was carried out with various repetition times of pulsed applied potential (0.25 s at -2.0 V vs. Ag/AgCl) in an aqueous solution of $HAuCl_4$. Significant progress of the number density of deposited gold nanoparticles was confirmed from scanning electron micrographs, from 4 (1 time) to 25% (15 times). Next, electropolymerization of 2,2'-bithiophene onto the above ITO electrode was performed under controlled charge condition (+1.4 V vs. Ag wire, 15 $mC/cm^2$). Structural characterization of as-fabricated films were carried out by spectroscopic and electron micrographic methods. Photocurrent responses from the sample film electrodes were investigated in the presence of electron acceptors (methyl viologen and oxygen). Photocurrent intensities increased with increasing the density of deposited gold nanoparticles up to ~10%, and tended to decrease above it. It suggests that the surplus gold nanoparticles exhibit quenching effects rather than enhancement effects based on localized electric fields induced by surface plasmon resonance of the deposited gold nanoparticles.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1983-1987
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• 2008

This study demonstrates the electrochemical conversion of the synthetic procedure of monolayer-protected clusters using a thin toluene layer over an edge plane pyrolytic graphite electrode. A thin toluene layer with a thickness of 0.31 mm was coated over the electrode and an immiscible liquid/liquid water/toluene interface was introduced. The transfer of the tetrachloroaurate ($AuCl_4^-$) ions into the toluene layer interposed between the aqueous solution and the electrode surface was electrochemically monitored. The $AuCl_4^-$ ions initially could not move through into the toluene layer, showing no reduction wave, but, in the presence of the phase transfer reagent, tetraoctylammonium bromide (TOABr), a cathodic wave at 0.23 V vs. Ag/AgCl was observed, indicating the reduction of the transferred $AuCl_4^-$ ions in the toluene layer. In the presence of dodecanethiol together with TOABr, a self-assembled monolayer was formed over the electro-deposited metallic gold surface. The E-SEM image of the surface indicates the formation of a highly porous metallic gold surface, rather than individual nanoparticles, over the EPG electrode.

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.169-175
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• 2018

Cu-Salen complex was prepared and attached into chitosan (Cs) polymer backbone. Nanocomposite of the synthesized polymer was prepared with functionalized carbon nano-particles (Cs-Cu-sal/C) to modify the electrode surface. The surface morphology of (Cs-Cu-sal/C) nanocomposite film showed a homogeneous distribution of carbon nanoparticles within the polymeric matrix. The cyclic voltammogram of the modified electrode exhibited a redox behavior at -0.1 V vs. Ag/AgCl (3 M KCl) in 0.1 M PB (pH 7) and showed an excellent hydrogen peroxide reduction activity. The Cs-Cu-sal/C electrode displays a linear response from $5{\times}10^{-6}$ to $5{\times}10^{-4}M$, with a correlation coefficient of 0.993 and detection limit of $0.9{\mu}M$ (at S/N = 3). The sensitivity of the electrode was found to be $0.356{\mu}A\;{\mu}M^{-1}\;cm^{-2}$.

• Journal of the Korean Electrochemical Society
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• v.8 no.3
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• pp.117-124
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• 2005

Electrochemical oxidation of ethanol at nickel electrodes has been studied in 1 M KOH solution containing 0.20M ethanol using electrochemical impedance spectroscopy. Equivalent circuits have been worked out by simulating the impedance data, and the results were used to model the oxidation of ethanol as well as the passivation of the electrode. The maximum rate of oxidation of $Ni(OH)_2$ to NiOOH was observed at about 0.37V vs. Ag/AgCl reference electrode, while the maximum rate of ethanol oxidation at the Ni electrode was observed at about 0.42V, The charge-transfer resistance for oxidation of the electrode itself became smaller in the presence of ethanol than in its absence. These results suggest that the $\beta-Ni(OH)_2/\beta-NiOOH$ redox couple is acting as an effective electron transfer mediator far ethanol oxidation. The kinetic parameters also were obtained by the experimental and simulated results.

• Analytical Science and Technology
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• v.14 no.2
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• pp.123-130
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• 2001

Determination of cadmium(II) ion with a perfluorinated sulfonated polymer-ethylenediamine(nafion-en) modified glassy carbon electrode was studied. It was based on the chemical reactivity of an immobilized layer(nafion-en) to yield complex $[Cd(en)_2]^{2+}$. The reduction peak potential by differential pulse voltammetry(DPV) was observed at $-0.780({\pm}0.005)V$ vs. As/AgCl. The linear calibration curve was obtained in cadmium(II) ion concentration range $5.0{\times}10^{-7}-2.0{\times}10^{-5}M$, and the detection limit(3s) was $2.20{\times}10^{-7}M$. The detection limit of nafion-en modified glassy carbon electrode has been shown about 14 higher sensitivity than a bare glassy carbon electrode.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.7-11
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• 2014

Recently, the buffer layers consisting of poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT-PSS) are extensively used to improve power conversion efficiency (PCE) of organic solar cells. However, PEDOT-PSS is not suitable for mass production of organic solar cells due to its intrinsic acid and hygroscopic properties. Moreover, because of chemical reactions between indium tin oxide (ITO) layer and PEDOT-PSS layer, the interface is not stable. For these reasons, alternative materials such as $V_2O_5$ have been developed to be an effective buffer layer. In this work, we used $V_2O_5$/Ag/ITO multilayer structure for the anode buffer layer. With variation of thickness of Ag layer, we investigated the optical and electrical properties of $V_2O_5$/Ag/ITO multi-layer films. As a result, we found that the electrical properties were improved with increasing Ag thickness while optical transmittance decreases in visible wavelength region. From the calculation of figure of merit (FOM) which is used to evaluate proper structure for transparent of optoelectronic, $V_2O_5$/Ag/ITO multilayer electrode was optimized with 4 nm thick Ag layer in optical (88% in transmittance) and electrical ($4{\times}10^{-4}{\Omega}cm$) properties. This indicates that $V_2O_5$/Ag/ITO multilayer electrode could be a candidate for the anode of optoelectronic devices.