RESUMO
Multilayer antireflection (AR) coatings require a material with a large and constant absorption coefficient over the whole visible range and thermal stability. Coatings for use in touch panel displays are also required to be electrically insulative. In this study, 60 mol % Ag-40 mol % (Fe1-xAlx)-O (x = 0, 0.25, 0.50, 0.75, and 1.0) thin films are prepared by pulsed laser deposition, and their optical properties, electric resistance, and thermal stability are clarified by combining the experimental data and density functional theory (DFT) calculations. Over the visible range, large and constant absorption coefficients are obtained for all compositions. The standard deviations of the absorption coefficients of the x = 0.75 and 1.0 samples are found to be smaller than those of conventional materials like graphite and CrOx. High sheet resistance (Rsheet > 107 Ω·sq-1) is also confirmed. It is determined that nanometer-sized Ag dispersed into a matrix, which was confirmed to be ionic Ag in the matrix phase, is responsible for the absorption at a shorter visible light range and insulative nature even at high Ag content. The films with high Al content are stable up to 500 °C. The potential of these black insulative Ag-Al-Fe-O thin films for use as black AR coatings is confirmed by optical simulations with multilayer stacks.
RESUMO
Sputter-deposited TiO2 films with high visible-light photocatalytic activity were successfully realized by a hybrid TiO2/Pt/WO3 film structure with Pt nanoparticles uniformly distributed at the interface of the TiO2 and WO3 films. The TiO2/Pt/WO3 hybrid films enable the complete decomposition of CH3CHO under visible-light irradiation. The water contact angle of the TiO2/Pt/WO3 hybrid films reaches below 5° under visible-light irradiation. Pt nanoparticles are considered to act as a cocatalyst to improve the electron-hole separation efficiency. We demonstrate that the photogenerated holes in WO3 are transferred to the surface of the TiO2 film with less hole-trapping and induce high visible-light photocatalytic activity and hydrophilic behavior, and the photogenerated electrons are accumulated in the Pt nanoparticles. The highly hydrophilic thin films with high visible-light photocatalytic activity can be applied to various indoor products possessing self-cleaning and antifogging properties.
