• Korean Journal of Materials Research
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• v.4 no.8
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• pp.861-869
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• 1994

Chemical vapor deposition using titanium tetra isopropoxide(TTIP) was employed to investigate effects of process parameters on the uniformity of $TiO_{2}$this films deposited on Indium Tin Oxide (ITO)coated glass. Deposition experiments were carried out at temperatures ranging from $300^{\circ}C$ to $400^{\circ}C$ under the pressure of 0.5~2 torrin a cold wall reactor which can handle 200mm substrate. It was found that the growth rate of $TiO_{2}$was closely related to the reaction temperature and the ractant gas compositions. Apparent activation energy for the deposition rate was 62.7lkJ/mol in the absence of $O_{2}$ and 100.4kj/mol in the presence of $O_{2}$, respectively. Homogeneous reactions in the gas phase were promoted when the total pressure of the reactor was increased. Variance in the film thickness was less than a few percent, but at high deposition rates film thickness was less uniform. Effects of reaction temperature on $TiO_{2}$ thin film characteristic was investigated with SEM, XRD and AES.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.82-84
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• 2013

We fabricated dye-sensitized solar cells (DSSCs) with $TiO_2$ nanowire (NW)/nanoparticle (NP) composite and solidified nanogel as the photoelectrode and electrolyte, respectively. $TiO_2$ NWs were generated via pore-infiltration of titanium (IV) isopropoxide (TTIP) into a track-etched polycarbonate membrane with a pore diameter of 100 nm, followed by calcination at $500^{\circ}C$. Energy conversion efficiency of $TiO_2$ NW/NP-based DSSCs was always higher than that of NP-based cells. We attributed this to improved light scattering and electron transport by $TiO_2$ NWs, as verified by intensity modulation photocurrent spectroscopy (IMPS) and intensity modulation photovoltage spectroscopy (IMVS) analyses. Quasi-solid-state DSSCs with NW/NP composites exhibited 5.0% efficiency at 100 $mW/cm^2$, which was much greater than that of NP-based cells (3.2%).

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.189-189
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• 2012

염료-감응형 태양전지 응용을 위하여 $TiO_2$ nanorods를 autoclave를 이용하여 FTO 기판위에 수열합성법으로 합성 하였다. $TiO_2$ nanorods는 증류수와 염산, Titanium tetra isopropoxide (TTIP) 전구체의 혼합 용액을 이용하여, $150-200^{\circ}C$의 온도에서 합성하였다. 합성된 $TiO_2$ nanorods의 두께와 길이, 밀도는 성장시간과 성장온도, 전구체의 양, 염산과 증류수의 비율 등의 성자조건 변화를 통하여 조절하였다. $TiO_2$ nanorods의 결정성과 표면형태를 관찰하기 위해 XRD, SEM 그리고 TEM을 이용하였으며, 광학적 특성을 관찰하기 위해서 UV-Vis을 측정하였다. 합성된 $TiO_2$ nanorods 형태는 수직으로 서장된 단결정 구조의 rutile 상으로 관찰되었으며, 길이는 약 $4-6{\mu}m$로 관찰되었다. 고온($200^{\circ}C$)에서 짧은 시간동안 성장시킨 $TiO_2$ nanorods가 태양전지에 응용이 유용한 샘플로 성장되었다. 또한, 반응시간과 전구체의 양이 증가할수록 $TiO_2$ nanorods의 밀도가 증가하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.349-349
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• 2010

$TiO_2$ thin films were prepared on C fibers, and photocatalytic activity of these films for removing gas-phase toluene was studied. $TiO_2$ films were deposited on C fiber with 0.5 A-per-cycle growth rate by Atomic Layer Deposition (ALD) using TTIP (titanium tetra-isopropoxide) and $H_2O$ as precursors. The catalysts were characterized by Brunauer-Emmett-Teller (BET) for surface area and Scanning Electron Microscope (SEM) for morphology, respectively. Moreover, the samples were further characterized by X-ray Photoelectron Spectroscopy (XPS). As a function of $TiO_2$ thickness, no significant change in the photocatalytic activity could be identified. Interestingly, the bare-carbon fiber showed an even higher photocatalytic activity than the $TiO_2$ thin films for removing toluene. Origin of the high photocatalytic activity of the bare C fiber is discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.317-317
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• 2010

This paper reports syntheses of $TiO_2$ nanocubes and theirs application to DSSC. We synthesized $TiO_2$ nanocubes via solvothermal method using titanium isopropoxide (TTIP) and tetramethylammoiumhydroxide (TMAH). By adding longer alkyl chain ammonium hydroxide that slowed down the growth rate of the crystal, $TiO_2$ nanocubes were obtained with average particle size in the range of 40 nm to 70 nm. By TEM investigation, each particle was found to be single crystal of anatase having six-faces of (001) and {100} crystallographic planes truncated by {101} series of planes, which are clearly distinguishable from spherical nanoparticles. Among various application, utilizing nanocubes as photo-electrode in dye-sensitized solar cell, we investigated photo-electron conversion performances in comparison with spherical shaped $TiO_2$ nanoparticles by I-V characteristics and IPCE measurements, etc.. Photocurrent-transient analysis revealed that $TiO_2$ nanocubes have a higher transient electron transfer rate by more than 10 times compared with spherical particles of similar size. Fast electron transport along the cube edges having small curvature was suggested as a plausible origin of high diffusion coefficient of electron in nanocube $TiO_2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.345-345
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• 2010

Thin film of $TiO_2$ deposited on carbon paper was fabricated by atomic layer deposition (ALD) using titanium isopropoxide (TTIP) and $H_2O$ as precursors. In this work, the photocatalytic activities of $TiO_2$ films with and without e-beam treatment were compared. The samples were treated by e-beam using e-beam energy of 1MeV and exposure range between 5 and 15kGy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyleneblue (MB) under UV irradiation (365nm) at room temperature using an UV-vis spectroscopy. The surface properties were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The sample treated by the low radiation dose has more catalytic activity than other ones. SEM images show that the high radiation dose caused the $TiO_2$ to aggregation on carbon paper. Due to the aggregation of $TiO_2$, the partially exposed carbon paper was oxidized.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.322-322
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• 2010

Recently, anti-reflective films (AR) are one of the most studied parts of a solar cell since these films improve the efficiency of photovoltaic devices. Also, anti-reflection films on the textured silicon solar cells reduce the amount of reflection of the incident light, which improves the device performance due to light trapping of incident light into the cell. Therefore, we preformed two step processes to get textured Si (100) substrate in this experiment. Pyramid size of textured silicon had approximately $2{\sim}9\;{\mu}m$. A well-textured silicon surface can lower the reflectance to 10%. For more reduced reflection, TiO2 anti-reflection films on the textured silicon were deposited at $600^{\circ}C$ using titanium tetra-isopropoxide (TTIP) as a precursor by metal-organic chemical vapor deposition (MOCVD), and the deposited TiO2 layers were then treated by annealing for 2 h in air at 600 and $1000^{\circ}C$, respectively. In this process, the treated samples by annealing showed anatase and rutile phases, respectively. The thickness of TiO2 films was about $75{\pm}5\;nm$. The reflectance at specific wavelength can be reduced to 3% in optimum layer.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.392-399
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• 2019

A highly transparent interfacial layer (HTIL) to enhance the performance of dye-sensitized solar cells (DSSCs) was prepared via a polymer-assisted (PA) approach. Poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom-transfer radical polymerization (ATRP) and was used as a sacrificial template. The PVC-g-POEM graft copolymer induced partial coordination of a hydrophilic titanium isopropoxide (TTIP) sol-gel solution with the POEM domain, resulting in microphase separation, and in turn, the generation of mesopores upon calcination. These phenomena were confirmed using Fourier-transform infrared (FT-IR) spectroscopy, UV-visible light transmittance spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The DSSCs incorporating HTIL60/20 (consisting of a top layer with a pore size of 60 nm and a bottom layer with a pore size of 20 nm) exhibited the best overall conversion efficiency (6.36%) among the tested samples, which was 25.9% higher than that of a conventional blocking layer (BL). DSSC was further characterized using the Nyquist plot and incident-photon to electron conversion efficiency (IPCE) spectra.

• Membrane Journal
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• v.21 no.2
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• pp.193-200
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• 2011

An amphiphilic graft copolymer comprising a poly(vinyl chloride) (PVC) backbone and poly (styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymerization (ATRP). Mesoporous titanium dioxide $(TiO_2)$ films with crystalline anatase phase were synthesized via a sol-gel process by templating PVC-g-PSSA graft copolymer. Titanium isopropoxide (TTIP), a $TiO_2$ precursor was selectively incorporated into the hydrophilic PSSA domains of the graft copolymer and grew to form mesoporous $TiO_2$ films, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The performances of dye-sensitized solar cell (DSSC) were systematically investigated by varying spin coating times and the amounts of P25 nanoparticies. The energy conversion efficiency reached up to 2.7% at 100 mW/$cm^2$ upon using quasi-solid-state polymer electrolyte.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.8-15
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• 2021

Transparent, photocatalytic, and self-cleaning TiO2 thin film is developed by TiO2 sol-gel coating on glass and polycarbonate (PC) substrates. Acetyl acetone (AcAc) suppresses the precipitation of TiO2 by forming a yellowish (complex) transparent sol-gel. XPS analysis confirms the presence of Ti2p and O1s in the thin films on glass and PC substrates. The TiO2-sol is prepared by stabilizing titanium (IV) isopropoxide (TTIP) with diethylamine and methyl alcohol. The addition of AcAcsilane coupling solution to the TiO2-sol instantaneously turns to yellowish color owing to the complexing of titanium with AcAc. The AcAc solution substantially improves the photocatalytic property of the TiO2 coating layer in MB solutions. The coated TiO2 film exhibits super hydrophilicity without and with light irradiation. The TiO2 thin film stabilized by adding 8.7 wt% AcAc shows the highest photo-degradation for methylene blue (MB) solution under UV light irradiation. Also, the optimum photocatalytic activity is obtained for the 8.7 wt% AcAc-stabilized TiO2 coating layer calcined at 450 ℃. The thin-films on glass exhibit fast self-cleaning from oleic acid contamination within 45 min of UV-light irradiation. The appropriate curing time at 140 ℃ improves the anti-fogging and thermal stability of the TiO2 film coated on PC substrate. The watermark-free PC substrate is particularly beneficial to combat fogging problems of transparent substrates.