• Korean Journal of Metals and Materials
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• v.50 no.11
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• pp.847-854
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• 2012

Al-doped ZnO (AZO) thin films were grown on quartz substrates by the sol-gel method. The effects of the Al mole fraction on the structural and optical properties of the AZO thin films were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-VIS spectroscopy. The particle size of the AZO thin films decreased with an increase in Al concentrations. The optical parameters, the optical band gap, absorption coefficient, refractive index, dispersion parameter, and optical conductivity, were studied in order to investigate the effects of Al concentration on the optical properties of AZO thin films. The dispersion energy, single-oscillator energy, average oscillator wavelength, average oscillator strength, and refractive index at an infinite wavelength of the AZO thin films were affected by the Al incorporation. The optical conductivity of the AZO thin films also increased with increasing photon energy.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.125-133
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• 2016

With the aim of using a filler material in a conductive paste, fine Cu nanoparticles were synthesized through the high-speed chemical reaction between cuprous oxide ($Cu_2O$) powder and sulfuric acid in distilled water. Under external temperature of $7^{\circ}C$, sulfuric acid concentration of 48%, and $Cu_2O$ amount of 30 g, the $Cu_2O$ particles were eliminated and slightly aggregated Cu nanoparticles were synthesized. Futhermore, Cu nanoparticles of 224 nm, in which the aggregation between particles was obviousiy much suppressed, were synthesized with the choice of an additive. In the particle sample, occasionally there are coarse particles formed by the aggregation of fine nanoparticles and weak linkages between the nanoparticles. However, the coarse particles were destroyed and the linkages were broken after mixing with a resin formulation, indicating the behavior of untangling the aggregation between nanoparticles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.441-441
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• 2009

Dye-sensitized solar cells (DSSCs) have been widely investigated as a next-generation solar cell because of their simple fabrication process and low coats. The cells use a porous nanocrystalline TiO2 matrix coated with a sensitizer dye that acts as the light-harvesting element. The photo-exited dye injects electrons into the $TiO_2$ particles, and the oxide dye reacts with I- in the electrolyte in regenerative cycle that is completed by the reduction of $I_3^-$ at a platinum-coated counter electrode. Since $TiO_2$ porous film plays a key role in the enhancement of photoelectric conversion efficiency of DSSC, many scientists focus their researches on it. Especially, a high light-to-electricity conversion efficiency results from particle size and crystallographic phase, film porosity, surface structure, charge and surface area to volume ratio of porous $TiO_2$ electrodes, on which the dye can be sufficiently adsorbed. Effective treatment of the photoanode is important to improve DSSC performance. In this paper, to obtain properties of surface and dispersion as nitric acid treated $TiO_2$ photoelectrode was investigate. The photovoltaic characteristics of DSSCs based the electrode fabricated by nitric acid pre-treatment $TiO_2$ materials gave better performances on both of short circuit current density and open circuit voltage. We compare dispersion of $TiO_2$ nanoparticles before and after nitric acid treatment and measured Ti oxidized state from XPS. Low charge transfer resistance was obtained in nitric acid treated sample than that of untreated sample. The dye-sensitized solar cell based on the nitric acid treatment had open-circuit voltage of 0.71 V, a short-circuit current of 15.2 mAcm-2 and an energy conversion efficiency of 6.6 % under light intensity of $100\;mWcm^{-2}$. About 14 % increases in efficiency obtained when the $TiO_2$ electrode was treated by nitric acid.

• KSBB Journal
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• v.24 no.6
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• pp.533-540
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• 2009

In this work, 5'-nitroindirubinoxime (5'-NIO) has been prepared as solid dispersions using a supercritical aerosol solvent extraction system (ASES) process in order to enhance its water solubility and dissolution rate. Solid dispersions of 5'-NIO and poly(vinyl pyrrolidone) (PVP) were prepared in various weight percent ratios. Three-component solid dispersions consisting of 5'-NIO, PVP, and poloxamer 188 (P188) were also prepared to study the influence of P188 level on their morphology, crystallinity, and dissolution behavior. All samples were prepared at $35^{\circ}C$ and 180 bar using supercritical carbon dioxide. The particle morphology and size of the two-component solid dispersions were found to be nearly spherical and much smaller (100-200 nm) compared with the original 5'-NIO. The morphology of three-component solid dispersions became more agglomerated as the level of P188 increased. The crystallinity of the original 5'-NIO was not observed in the solid dispersions prepared by the ASES process. Faster dissolution rates were observed for the three-componet solid dispersions because the arrangement of ethylene oxide and propylene oxide blocks of the poloxamer 188 enabled the formation of micelles in an aqueous phase.