• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.424-424
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• 2008

Dye-sensitized Solar Cell (DSC) is a new type of solar cell by using photocatalytic properties of $TiO_2$. The electric potential distribution in DSCs has played a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage(Voc) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. $TiO_2$ thin films were deposited on the FTO substrate by Nd:YAG Pulsed Laser Deposition(PLD) at room temperature and post-deposition annealing at $500^{\circ}C$ in flowing $O_2$ atmosphere for 1 hour. The structural properties of $TiO_2$ thin films have investigated by X-ray diffraction(XRD) and atomic force microscope(AFM). Thickness of $TiO_2$ thin films were controlled deference deposition time and measurement by scanning electron microscope(SEM). Then we manufactured a DSC unit cells and I-V and efficiency were tested using solar simulator.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.215-220
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• 2016

A new immobilization technique of nanoscale $TiO_2$ powder to expanded polystyrene (EPS) balls with temperature-controlled melting method was developed, and the photocatalytic activity of $TiO_2$ powder-embedded EPS balls were evaluated using methylene blue (MB) solution under ultraviolet irradiation (${\lambda}=254nm$). Based on the scanning electron microscope (SEM) images and associated energy-dispersive X-ray spectroscopy (EDX) analysis, the components of the intact EPS balls were mainly carbon and oxygen, whereas those of $TiO_2$-immobilized EPS balls were carbon, oxygen, and titanium, indicating that relatively homogenous patches of $TiO_2$ and glycerin film were coated on the surface of EPS balls. Based on the comparison of degradation efficiencies of MB between intact and $TiO_2$-immobilized EPS balls under UVC illumination, the degradation efficiencies of MB can be significantly improved using $TiO_2$-immobilized EPS balls, and surface reactions in heterogeneous photocatalysis were more dominant than photo-induced radical reactions in aqueous solutions. Thus, $TiO_2$-immobilized EPS balls were found to be an effective photocatalyst for photodegradation of organic compounds in aqueous solutions without further processes (i.e., separation, recycling, and regeneration of $TiO_2$ powder). Further study is in progress to evaluate the feasibility for usage of buoyant $TiO_2$-immobilized EPS to inhibit the excessive growth of algae in rivers and lakes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.154-157
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• 2003

$TiO_2$ thin films were fabricated by RF magnetron sputtering system at by controlling deposition times, ratios of $Ar:O_2$ partial presser ratio and substrate conditions. And the surface, cross-section morphology, microstructure, and composition ratio of the films were analyzed by FE-SEM, TEM and XPS. Besides, the optical absorption and transmittance of the $TiO_2$ films were measured by a UV-VIS-NIR Spectrophotometer, and photocatalytic properties were studied by G${\cdot}$C Analyzer & Data Analysis system. As the result, when $TiO_2$ thin film was made at deposition time of 120[min] and $Ar:O_2$ ratio of 60:40, the best structural and optical properties among many thin films could be accepted. The best results of properties were as follows: thickness; 360~370[nm), grain size; 40[nm], gap between two peak binding energy; $5.8{\pm}0.05[eV]$ ($2_{p3/2}$ peak and $2_{p1/2}$ peak of Ti was show at $458.3{\pm}0.05[eV]$ and $464.1{\pm}0.05[eV]$ respectively), binding energy; $530{\pm}0.05[eV]$, optical energy band gap; 3.4[eV].

• Journal of Hydrogen and New Energy
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• v.11 no.4
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• pp.161-169
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• 2000

In the case of photocatalytic hydrogen production from water, the performance-property relationships of CdS-TiO2 film type composite catalysts were investigated. To control the physical properties of the primary particles, the mixture of CdS and TiO2 nano-sols prepared by the sol-gel method at room temperature was hydrothermally treated at 240oC for 12hr. The film electrodes were prepared by the casting method. The photocurrents measured by a photoelectrochemical method and the hydrogen production rates measured by a photochemical method were closely dependent on the physical properties such as crystalline form, primary particle size and CdS/TiO2 mole ratio, and these varied in the range of 1.2~2.6 mA/cm2 and $1.0{\sim}1.6{\times}10-3mol/hr$, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.6
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• pp.267-271
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• 2010

Super hydrophilic and high transparent $TiO_2$ thin films were successfully fabricated by sol-gel method without an irradiation of UV light. In addition, surfactant Tween 80 was used for increasing the transmittance of the thin films. When the contents of Tween 80 in $TiO_2$ solution were 0.0, 1.0, 3.0, 5.0 wt%, the transmittance of $TiO_2$ thin films was ca. 74.31%, 74.25%, 79.69%, 81.99% at 550 nm wavelength, respectively. The contact angles of fabricated $TiO_2$ thin films with or without Tween 80 were from ca. $4.0^{\circ}$ to $4.5^{\circ}$. The $TiO_2$ thin films annealed over $400^{\circ}C$ showed anatase crystal structure and the photocatalytic property that decomposed methyl orange with UV irradiation. The surface morphologies, optical properties and contact angle of prepared thin films with different contents of Tween 80 were evaluated by field emission scanning electron microscope (FE-SEM), X-ray diffratometer (XRD), UV-Vis spectrophotometer and contact angle meter.