• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.7.2-7.2
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• 2011

Photoelectrochemical solar cells such as dye-sensitized cells (DSSCs), which exhibit high performance and are cost-effective, provide an alternative to conventional p-n junction photovoltaic devices. However, the efficiency of such cells plateaus at 11~12%, in contrast to their theoretical value of 33%. The majority of research has focused on improving energy conversion efficiency of DSSC by controlling nanostructure and exploiting new materials in photoelectrode consisting of semiconducting oxide nanoparticles and a transparent conducting oxide electrode (TCO). In this presentation, we introduce monodisperesed TiO2 nanoparticles prepared by forced hydrolysis method and their superiority as photoelectrode materials was characterized with aids of optical and electrochemical analysis. Inverse opal-based scattering layers containing highly crystalline anatase nanoparticles are also introduced and their feasibility for use as bi-functional light scattering layer is discussed in terms of optical reflectance and charge generation properties as a function of optical wavelength.

• Journal of the Korean Ceramic Society
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• v.21 no.3
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• pp.266-270
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• 1984

The photoelectrochemical properties of the reduced $TiO_2$ceramic electrodes are investigated varying the thickness of the electrodes and the amounts of $Sb_2O_3$ as dopant. As the thickness of the undoped. $TiO_2$ceramic electrode increases the photocurrent tends to decrease. However for the R-F sputtered $TiO_2$ thin film electrodes the photocurrent tends to increase to about 1$\mu\textrm{m}$ thick and then decreases with increasing thickness. For the $TiO_2$ ceramic electrodes doped with $Sb_2O_3$ the photocurrent decreases with inreasing the amounts of dopant and in the case of rapid cooling in air without reduction treatment the photocurrent shows lower value. Also visible light excitation is observed at 500~550(nm) wavelength for the $TiO_2$ ceramic electrodes doped with $Sb_2O_3$comparing wtih the $TiO_2$ ceramic electrodes (~420nm)

• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.264-268
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• 2018

Vertically-aligned $TiO_2$ nanotube electrodes have attracted considerable attention for applications in solar cells, catalysts, and sensors, because of their ideal structure for electron transport and electrolyte diffusion. Here, we prepare vertically-aligned $TiO_2$ nanotube electrodes using a two-step anodization process. The prepared $TiO_2$ nanotube electrodes exhibit uniform pore structures with an inner diameter of ~80-90 nm and wall thickness of ~20-25 nm. In addition, they exhibit an anatase crystal phase after a high-temperature annealing. The annealed $TiO_2$ nanotube electrodes are applied in dye-sensitized solar cells (DSSCs) as photoanodes. The fabricated DSSC exhibits conversion efficiencies of 3.46 and 2.15% with liquid- and gel-type electrolytes, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.360-361
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• 2008

A new kind of SBM co-polymer binder as styrene, n-butyl acrylate, and methacrylic acid (SBM) monodisperse co-polymer binder materials basted on $TiO_2$ pastes was synthesized and this $TiO_2$ pastes were applied of dye-sensitized solar cells (DSSCs). The SBM co-polymer binder was prepared by soap-free emulsion copolymerization using a PEG-EEM macromonomer. The photoanodes were characterized by morphology investigated from field emission scanning electron microscopy (FE-SEM). The photoelectrochemical properties of the thin films and the performance of DSSCs were measured by photovoltaic-current density. DSSC based on the emulsion co-polymer binder was obtained conversion efficiency of 7.1% under irradiation of AM 1.5($100mWcm^{-2}$).

• Analytical Science and Technology
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• v.11 no.1
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• pp.20-28
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• 1998

Fluorimetric and absorption spectroscopic studies were performed to elucidate the photocurrent decay with time in the conversion process of solar energy into electrical energy using a photoelectrochemical cell containing rose bengal as a sensitizer, and allylthiourea as a supersensitizer. Spectra of dye solution before and after irradiation revealed a new photocatalytic dimerization reaction between sensitizer and supersensitizer. It was also found that the geometrical arrangement of the transition dipoles is oblique in the dimer of dye molecules.

• Analytical Science and Technology
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• v.11 no.1
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• pp.13-19
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• 1998

In the dye sensitization for the solar energy conversion with a photoelectrochemical cell containing allylthiourea, the time profile of the sensitized photocurrent showed a rise and fall with the irradiation time. The dye solution before and after irradiation was analyzed by means of spectroscopic methods. A new precipitation reaction between sensitizer and supersensitizer and photobleaching of the dye appeared to be involved in the decreased photocurrent.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.28-28
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• 2010

Photoelectrochemical solar cells such as dye-sensitized cells (DSSCs), which exhibit high performance and are cost-effective, provide an alternative to conventional p-n junction photovoltaic devices. However, the efficiency of such cells plateaus at 11-12%, in contrast to their theoretical value of 33%. Improvements in efficiency can only occur through a fundamental understanding of the underlying physics, materials, and device designs of DSSCs. A photoelectrode consisting of semiconducting oxide nanoparticles and a transparent conducting oxide electrode (TCO) is a key component of DSSC and design of photoelectrode materials is one of promising strategies to improving energy conversion efficiency. We introduce monodisperesed $TiO_2$ nanoparticles prepared by forced hydrolysis method and their superiority as photoelectrode materials was characterized with aids of optical and electrochemical analysis. Multi-layered TCO materials are also introduced and their feasibility for use as photoelectrodes is discussed in terms of optical absorption and charge collecting properties.

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.400-405
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• 2016

Ferric oxide (${\alpha}-Fe_2O_3$, hematite) is an n-type semiconductor; due to its narrow band gap ($E_g=2.1eV$), it is a highly attractive and desirable material for use in solar hydrogenation by water oxidation. However, the actual conversion efficiency achieved with $Fe_2O_3$ is considerably lower than the theoretical values because the considerably short diffusion length (2-4 nm) of holes in $Fe_2O_3$ induces excessive charge recombination and low absorption. This is a significant hurdle that must be overcome in order to obtain high solar-to-hydrogen conversion efficiency. In consideration of this, it is thought that elemental doping, which may make it possible to enhance the charge transfer at the interface, will have a marked effect in terms of improving the photoactivities of ${\alpha}-Fe_2O_3$ photoanodes. Herein, we report on the synthesis by pulsed electrodeposition of ${\alpha}-Fe_2O_3$-based anodes; we also report on the resulting photoelectrochemical (PEC) properties. We attempted Ti-doping to enhance the PEC properties of ${\alpha}-Fe_2O_3$ anodes. It is revealed that the photocurrent density of a bare ${\alpha}-Fe_2O_3$ anode can be dramatically changed by controlling the condition of the electrodeposition and the concentration of $TiCl_3$. Under optimum conditions, a modified ${\alpha}-Fe_2O_3$ anode exhibits a maximum photocurrent density of $0.4mA/cm^2$ at 1.23 V vs. reversible hydrogen electrode (RHE) under 1.5 G simulated sunlight illumination; this photocurrent density value is about 3 times greater than that of unmodified ${\alpha}-Fe_2O_3$ anodes.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1485-1486
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• 2011

A layer of $TiO_2$ thin film less than ~500nm in thickness, as a blocking layer, was coated by sol-gel method directly onto the anode electrode to be isolated from the electrolyte in dye-sensitized solar cells (DSCs). This is to prevent the electrons from back-transferring from the electrode to the electrolyte (I-/I3-). The effects of heat treatment conditions of the gel and as-coated film on the thickness and consolidation to substrate were studied. The flexible DSCs were fabricated with working electrode of Ti thin foil coated with blocking $TiO_2$ layer, dye-attached mesoporous $TiO_2$ film, gel electrolyte and counter electrode of Pt-deposited indium doped tin oxide/polyethylene naphthalate (ITO/PEN). The photo-current conversion efficiency of the cell was 5.3% ($V_{oc}=0.678V$, $J_{sc}=12.181mA/cm^2$, ff=0.634) under AM1.5, 100 mW/$cm^2$ illumination.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.120.2-120.2
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• 2011

The improvement of solar energy-to-electricity conversion efficiency has continued to be an important research area of dye-sensitized solar cells (DSSCs). The mechanism of DSSCs is based on the injection of electrons from the photoexcited dye into the conduction band of nanocrystalline TiO2 or ZnO. Thus, the electronic structures, such as HOMO, LUMO, and HOMO-LUMO band gaps of dye moleculed in DSSC are deeply related to the electron transfer by photoexcitation and redox potential. Organic dyes, because of their many advantages, such as high molar extinction coefficients, convenience of customized molecular design for desired photophysical and photochemical properties, inexpensiveness with no transition metals contained, and environment-friendliness, are suitable as photosensitizers for DSSC. We believe that practically useful organic dye photosensitizers can be produced by exploiting electron donor/acceptor system with proper length of ${\pi}$-conjugation in a chromophore to control the absorption wavelength and enhance the photovoltaic performance. In this research, We designed and synthesized organic dyes also investigated the photoelectrochemical properties of a series of ionic dyes in DSSCs.