Showing papers by "Yasunori Taga published in 2007"
15 Oct 2007
TL;DR: In this article, the authors report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550°C in flowing N 2 gas.
Abstract: We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 °C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation–recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N.
55 citations
TL;DR: In this article, the present status of passivation films with organic/Inorganic multilayer structure on flexible organic film substrate designed for electronic devices such as organic light emitting diode (OLED).
Abstract: This review paper describes the present status of passivation films with organic/Inorganic multilayer structure on flexible organic film substrate designed for electronic devices such as organic light emitting diode (OLED). Passivation film of SiNx/CN:H multilayer showed an excellent barrier properties for water and oxygen and strongly suppressed an appearance of dark spots on OLED surface during operation. The luminous efficiency of flexible OLED thus formed with passivation films revealed to be equivalent to that on glass substrate encapsulated by can. substrate.
4 citations
TL;DR: In this article, the photochemical reaction of volatile organic compounds (VOC's), such as acetaldehyde and toluene, over nitrogen doped TiO2(TiO-N) under visible light irradiation, using liquid chromatography, gas chromatography and gas chromatograph mass spectrometer (GC-MS) for gases analysis, and diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) and ion chromatography (IC) for adsorbed organics.
Abstract: We report the photochemical reaction of volatile organic compounds (VOC's), such as acetaldehyde and toluene, over nitrogen doped TiO2(TiO-N) under visible light irradiation, using liquid chromatography (LC), gas chromatography (GC) and gas chromatograph mass spectrometer (GC-MS) for gases analysis, and diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) and ion chromatography (IC) for adsorbed organics. We evaluated the photo degradation rates and intermediates for the above gases. As a result, the degradation rates of acetaldehyde gas on TiO-N were 1.2-3 times greater than those on TiO2, and those of toluene gas on TiO-N were 4-49 times greater than those on TiO2. Low concentrations of acetone and acetic acid were produced during the photo degradation of acetaldehyde by the TiO-N. From toluene, very low concentrations of formaldehyde, acetaldehyde, acetone and benzaldehyde gases were produced. We also revealed the decomposition processes of toluene. Results obtained indicate that toluene, weakly adsorbed on the photocatalyst surface, is initially photooxidized to benzaldehyde which adsorbs onto the TiO-N surface more strongly, leading to the formation of ring-opening products such as carboxylic acids and aldehydes. These intermediate products were gradually photodegraded to CO2 and H2O under visible light irradiation.