• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.313-313
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• 2010

The performance of polymer photovoltaic cells based on blends of poly(3-hexylyhiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) is strongly influenced by blend composition and thickness. Polymer photovoltaic cells based on bulk-heterojunction have been fabricated with a structure of ITO/poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)-pentacene/poly (3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM)/Al. We have prepared PEDOT:PSS by dissolving pentacene in N-methylpyrrolidine (NMP) and mixing with PEDOT:PSS. Pentacene was added a maximum concentration of approximately 5.5mg to the PEDOT:PSS solution and sonicated for 10 min. Active layer (P3HT:PCBM) (1:1) was strongly influenced by PEDOT:PSS-pentacene. We have investigated the performance of photovoltaic device with different concentration of P3HT:PCBM (1:1) 2.0wt%, 2.2wt%, 2.4wt% and 2.6wt%, respectively. The photocurrent and power conversion efficiency (PCE) showed a maximum between 2.0wt% and 2.2wt% concentration of P3HT:PCBM. This implied that both morphology and electron transport properties of the layer influenced the performance of the present photovoltaic cells. As the concentration of P3HT:PCBM blends as an active layer was increased, the power conversion efficiency was decreased. P3HT:PCBM layer and PEDOT:PSS-pentacene layer were characterized by work function, UV-visible absorption, atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscope (SEM).

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.549-555
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• 1996

Diamond Like Carbon film is amorphous film which is considered to consist of three coordinate graphite structure and tetrahedron coordinate diamond structure. Its hardness, thermal conductivity and chemical stability are nearly to one of diamond. It is well known to become semi-conductor by doping of inpurity. In this study Diamond Like Carbon film was synthesized by Microwave Plasma CVD in the gas mixture of hydrogen-methan-nitrogen and doped of nitrogen on the single-crystal silicon or silica glass. The temperature of substrate and nitrogen concentration in the gas mixture had an effect on the bonding state, structural properties and conduction mechanism. The surface morphology was observed by Scanning Electron Microscope. The strucure was analyzed by laser Raman spectrometry. The bonding state was evaluated by electron spectroscopy. Diamond Like Carbon film synthesized was amorphous carbon containing the $sp^2$ and $sp^3$ carbon cluster. The number of $sp^2$ bonding increased as nitrogen concentration increased from 0 to 40 vol% in the feed gas at 1233K substrate temperature and at $7.4\times10^3$ Pa. Increase of nitrogen concentration made Diamond Like Carbon to be amorphous and the doze of nitragen could be controlled by nitrogen concentration of feed gas.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.219-248
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• 1989

The purposes of this study were to analyze the microstructural and compositional changes of metal surfaces following different conditions of preoxidizing heat treatment, to investigate the composition of metal oxides, and to evaluate the effect of preoxidation and removal of surface oxides on microstructure and diffusion profiles. The techniques of EDAX (energy-dispersive analysis of x-ray), ESCA (electron spectroscopy for chemical analysis), and EPMA (electron probe micro analysis) were used, along with SEM (scanning electron microscopy). The obtained results were as follows : 1. A surface of the specimen became rough and the amount of the metal oxides increased with increasing the heat treatment time and temperature and the partial pressure of oxygen. 2. At an air pressure of 28' vacuum, the higher the temperature and the longer the time of preoxidation, the higher Ni concentration was detected. 3. Cr concentration in the specimen heat treated with air was higher than that of with vacuum. 4. The oxides in the specimens were mainly composed of Ni and Cr oxides. On the globular growth particles, significant rises in Al concentration of Rexillium III and Ti concentration of Verabond were noted. 5. Atomic diffusion occurred at the ceramic-metal interface, furthermore the amount of the flux was increased with preoxidation heat treatment.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.3
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• pp.140-143
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• 2011

In this work, Ga doped ZnO (GZO) films were prepared by radio frequency (RF) magnetron sputtering without intentional substrate heating on glass substrate and then the effect of the intense electron irradiation on structural and electrical properties and the NOx gas sensitivity were investigated. Although as deposited GZO films showed a diffraction peak for ZnO (002) in the XRD pattern, GZO films that electron irradiated at electron energy of 900 eV showed the higher intense diffraction peaks than that of the as deposited GZO films. The electrical property of the films are also influenced with electron's energy. As deposited GZO films showed the three times higher resistivity than that of the films irradiated at 900 eV In addition, the sensitivity for NOx gas is also increased with electron irradiation energy and the film sensor showed the proportionally increased gas sensitivity with NOx concentration. This approach is promising in gaining improvement in the performance of thin film gas sensors used for the detection of hazard gas phase.

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.1
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• pp.23-33
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• 2011

This experimental focus to characterize luminescence properties related to CNT (Carbon Nano Tube) element dispersedly implanted in ZnS-based phosphor thin film panel fabricated by a screen printing method. More specifically FE-SEM measurements, L-V(Luminescence vs. Voltage) and photo luminescence were carried out to determine an optimum value of CNT concentration and film thickness for the thin film structure of CNT-ZnS:(Cu, Al) by the screen printing method. We confirmed that an optimum value of CNT concentration in the ZnS:(Cu, Al) film panel is about 0.75 wt% resulting that the electric conductivity is 1.6 times higher than that of pure CNT sample and showing that the luminescence intensity is increasing until the optimum concentration. Clearly, CNT is presenting in the luminescence process providing a pathway for the creation of hot electron and a channel for the electron-hole recombination but overly inserted CNT may hinder to produce the hot electron for making an avalanching process. In case of the overly doped CNT 1.0 wt% in the ZnS-based phosphor, the luminescence intensity is decreasing although the electric conductivity is exponentially increasing. Based on these results, we realized that hot electron occurred by the external electric field or exciton arose by the external photon source are reduced dramatically over the critical value of CNT concentration because CNT element provide various isolated residues in the composites of ZnS based phosphor rather than pathway or channel for the D-A(Donnor to Acceptor) pair transition or the radiative recombination of electron-hole.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.380-384
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• 1987

Reactions of methylenethioxanthene (3) with n-propanethiol in the presence of di-t-butyl peroxide(DTBP) afforded preferentially propyl 9-thioxanthenylidenemethyl sulfide(8) rather than propyl 9-thioxanthenylmethyl sulfide(9) regardless of the concentration of n-propanethiol. On the other hand reactions of 3 with a low concentration of n-propanethiol in the presence of dibenzoyl peroxide(DBPO) gave 8, 1,2-bisthioxanthenylidene ethane(11), and thioxanthenylidenemethyl benzoate(12) but only 8 was formed at high concentration of the thiol. The formations of these products were rationallized by an electron transfer mechanism.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.1
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• pp.54-58
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• 2017

The effect of low temperature ($250^{\circ}C$) heat treatment after electron irradiation (irradiation time = 30, 180, 300s) on the chemical bonding and electrical properties of ZnO thin films prepared using a sol-gel process were examined. XPS (X-ray photoelectron spectroscopy) analysis showed that the electron beam irradiation decreased the concentration of M-O bonding and increased the OH bonding. As a result of the electron beam irradiation, the carrier concentration of ZnO films increased. The on/off ratio was maintained at ${\sim}10^5$ and the $V_{TH}$ values shifted negatively from 11 to 1 V. As the irradiation time increased from 0 to 300s, the calculated S. S. (subthreshold swing) of ZnO TFTs increased from 1.03 to 3.69 V/decade. These values are superior when compared the sample heat-treated at $400^{\circ}C$ representing on/off ratio of ${\sim}10^2$ and S. S. value of 10.40 V/decade.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.505-510
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• 2012

Cobalt oxide nanostructure materials have been prepared by adding several concentrations of spectator Ni ions in solution, and analyzed by electron microscopy, X-day diffraction, calorimetry/thermogravimetric analysis, UV-vis absorption, Raman, and X-ray photoelectron spectroscopy. The electron microscopy results show that the morphology of the nanostructures is dramatically altered by changing the concentration of spectator ions. The bulk XRD patterns of $350^{\circ}C$-annealed samples indicate that the structure of the cobalt oxide is all of cubic Fd-3m $Co_3O_4$, and show that the major XRD peaks shift slightly with the concentration of Ni ions. In Raman spectroscopy, we can confirm the XRD data through a more obvious change in peak position, broadness, and intensity. For the un-sputtered samples in the XPS measurement process, the XPS peaks of Co 2p and O 1s for the samples prepared without Ni ions exhibit higher binding energies than those for the sample prepared with Ni ions. Upon $Ar^+$ ion sputtering, we found $Co_3O_4$ reduces to CoO, on the basis of XPS data. Our study could be further applied to controlling morphology and surface oxidation state.

• Carbon letters
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• v.26
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• pp.88-94
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• 2018

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to $3.0{\mu}M$ with a relatively low limit of detection of $0.27{\mu}M$. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

• Toxicological Research
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• v.11 no.1
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• pp.57-62
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• 1995

To investigate the ultrastructural changes of kidney and clarify to a cause of its changes in lead intoxicated rats, the 0.5% lead acetate administed orally to the rats and those were sacrifled at 2 day, 1, 2, 4, 6 and 8 week after the treatment of lead acetate. Each extirpated kidney was histopathologically examined under the electron microscopy and histochemical examination was also carried out. Concomitantly, the activity of free radical metabolizing enzyme was determined. The blood levels of lead concentration showed a gradual increase from the first group reaching the plateau at the one or two week group with the slightly decreasing value throughout the whole course of the experiment. And the urinary ALA concentration showed a gradual increase from the first group to the 8 week group. In the kidney tissue of rat sacrified at 6 week, the proximal tubular cells showed dilatation of endoplasmic reticulum, mitochondrial swelling, increased numbers of secondary lysosomes and myelin figure-like residual bodies on electron microscope and oxygen free radicals are identified by histochemistry on light microscope whereas there were no differences in the activity of catalase and glutathione peroxidase between the lead acetate treated group and control group. But the activity of xanthine oxidase was more increased in lead acetate treated rats than control group. Furthermore, the superoxide dismutase activity was significantly increased in the experimental group than the control group. In conclusion, it is assumed the kidney damage in lead intoxicated rat may be induced by free radicals.