Inorganic Oxide Films Research Articles

Selective positioning of organic dyes in a mesoporous inorganic oxide film

Although sequential adsorption of dyes in a single TiO(2) electrode is ideal to extend the range of light absorption in dye-sensitized solar cells, high-temperature processing has so far limited its application. We report a method for selective positioning of organic dye molecules with different absorption ranges in a mesoporous TiO(2) film by mimicking the concept of the stationary phase and the mobile phase in column chromatography, where polystyrene-filled mesoporous TiO(2) film is explored for use as a stationary phase and a Brønsted-base-containing polymer solution is developed for use as a mobile phase for selective desorption of the adsorbed dye. By controlling the desorption and adsorption depth, yellow, red and green dyes were vertically aligned within a TiO(2) film, which is confirmed by an electron probe micro-analyser. The external quantum efficiency (EQE) spectrum from a solar cell with three selectively positioned dyes reveals the EQE characteristics of each single-dye cell.

Liquid-phase deposition and the properties of thin zirconium dioxide films on different substrates

In recent years, the interest of the researchers to the methods of synthesis of inorganic thin oxide films from low-temperature liquid solutions permanently increases. This is explained by the recent achievements in the technology of deposition of the films, including, in particular, chemical deposition, sputtering, laser ablation, and evaporation. The liquid-phase deposition is an aqueous procedure of deposition of oxide films. In our investigation, we try to improve the adhesion and stability of zirconium-oxide coatings on polymers. Ceramic coatings (ZrO2) protect the surface of the substrate against reactions with acids and oxidation. The deposition of ceramic coatings on polymers is connected with serious problems due to the sensitivity of polymers to the action of chemical reagents and high temperature. We make an attempt to explain the role of the substrate in the process of deposition of zirconium-oxide films from the liquid phase on the Kapton polymeric material with different types of surface treatment. It is shown that even insignificant variations of the pH value, temperature, and composition of the solution can noticeably affect the crystalline film, adhesion, and growth rate. Thin films are very smooth, homogeneous, and characterized by the presence of an insignificant number of cracks.

The Fast Response Electrochromic Device with Inorganic Tantalum Oxide Films as an Ion Storage Layer

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Polyelectrolyte-Mediated Assembly of Copper-Phthalocyanine Tetrasulfonate Multilayers and the Subsequent Production of Nanoparticulate Copper Oxide Thin Films

An approach to producing films of nanometer-sized copper oxide particulates, based on polyelectrolyte-mediated assembly of the precursor, copper(II)phthalocyanine tetrasulfonate (CPTS), is described. Multilayered CPTS and polydiallyldimethylammonium chloride (PDADMAC) were alternately assembled on different planar substrates via the layer-by-layer (LbL) procedure. The growth of CPTS multilayers was monitored by UV-visible spectrometry and quartz crystal microbalance (QCM) measurements. Both the UV-visible spectra and the QCM data showed that a fixed amount of CPTS could be attached to the substrate surface for a given adsorption cycle. Cyclic voltammograms at the CPTS/PDADMAC-covered gold electrode exhibited a decrease in peak currents with the layer number, indicating that the permeability of CPTS multilayers on the electrodes had diminished. When these CPTS multilayered films were calcined at elevated temperatures, uniform thin films composed of nanoparticulate copper oxide could be produced. Ellipsometry showed that the thickness of copper oxide nanoparticulate films could be precisely tailored by varying the thickness of CPTS multilayer films. The morphology and roughness of CPTS multilayer and copper oxide thin films were characterized by atomic force microscopy. X-ray diffraction (XRD) measurements indicated that these thin films contained both CuO and Cu2O nanoparticles. The preparation of such copper oxide thin films with the use of metal complex precursors represents a new route for the synthesis of inorganic oxide films with a controlled thickness.

A Simple Approach to Synthesize and Bond Organosiloxane Films on Injection-Molded Polyolefins

A simple method was devised to fabricate and anchor organosiloxane coatings along low-surface-energy plastics without resorting to chemical pre-treatment of the polymer surface. Polypropylene tubes were purposely distended by exposure to toluene-based solutions. An established solvent of many organic polymers and compounds, toluene not only perfused into the plastic via gradual intercalation of accessible polymer chains, but it also facilitated the entry of less compatible reagents as co-perfusates. The reagents, typically aminoalkyl si lanes, were activated either concomitant to perfitsion of polypro-pylene or during a subsequent hydrolysis step. Freed silanol groups, interacting along and beneath the Surface of the plastic, reacted to form a network held together by siloxane bonds. The type of network formed and presented herein was interpreted as an amorphous aminopropylsiloxane-silanol hydrate film, with overall thickness partially submerged and caught in the matrix of the plastic. This concept to intertwine a growing organosiloxane network and a compliant matrix precluded the conventional methods normally used to improve bonding on hydrophobic plastics. A comparison of ninhydrin color yields suggested that films were more effectively and conveniently synthesized when aminopropyltri-methoxysilane was applied in water-saturated toluene. It follows that by integrating low-temperature hydrothermal processing into this strategy, inorganic-organic hybrids or inorganic oxide films may be formed oil pre-molded plastics and feature traits such as covalent-like fastness and gas impermeability.

Reversible super-hydrophobicity to super-hydrophilicity transition of aligned ZnO nanorod films.

Remarkable surface wettability transition occurs with an inducement of ultraviolet (UV) for aligned ZnO nanorod films. The inorganic oxide films, which show super-hydrophobicity (left), become super-hydrophilic (right) when exposed to UV illumination. After the films are placed in the dark, the wettability evolves back to super-hydrophobicity. This reversible effect is ascribed to the cooperation of the surface photosensitivity and the aligned nanostructure. Such special property will greatly extend the applications of ZnO films.

Infrared reflection-absorption characterization of TiO 2 films on ITO: detection of LO modes

By exploiting the high reflectivity of ITO substrates in the infrared and the detection of longitudinal optical (LO) modes provided by oblique incidence of radiation (Berreman effect), we showed that reflection-absorption experiments in the MID-IR can be successfully performed when thin inorganic oxide films deposited on ITO are used as samples. The samples we used were TiO 2 films deposited on ITO by a sol-gel method. After being annealed at different temperatures, the films presented different structures, which could be detected by the IR spectra. Cyclic voltammograms of the samples were also presented and correlated to the IR spectra. Since we expect that other inorganic oxides can yield similar results, this simple, non-destructive and inexpensive technique can be routinely used in an electrochemical laboratory.

Preparation of Lead Titanate Thin Films Using Langmuir-Blodgett Method

The Langmuir-Blodgett (LB) method is investigated as a process in the fabrication of ferroelectric thin films such as lead titanate. LB film was fabricated by depositing a monolayer prepared by stearic acid (C17H35COOH), lead chlorides (PbCl2) and titanium bis(ammonium lactato)([CH3CH(O–)CO2NH4]2Ti(OH)2). As a conversion process from the LB film containing lead and titanium to an inorganic film, ultraviolet/ozone (UVO) treatment was found to be extremely applicable at a rate of about 4 min per monolayer. Subsequent rapid thermal annealing (RTA) resulted in a dense oxide thin film. The thickness of an oxide thin film converted from the LB film consisting of 301 layers was approximately 30 nm. Hence, it is considered that approximately 0.1 nm of the oxide layer is equivalent to the thickness of the film deposited by each cycle. From an X-ray diffraction pattern of the oxide specimen, a well-defined perovskite peak structure was observed. These results demonstrate the potential application of LB deposition for the preparation of an inorganic oxide film such as lead titanate.

Fabrication of ultrathin metal oxide films using Langmuir–Blodgett deposition

Thin Y2O3 films have been fabricated using a Langmuir–Blodgett (LB) process. Uniform LB films of yttrium arachidate have been successfully deposited up to 200 layers. These films were found to decompose uniformly above 300 °C leaving a thin oxide layer. X-ray diffraction, laser reflection, and Rutherford backscattering have been used to determine crystal structure and stoichiometry of the film before, during, and after thermal decomposition. This test system demonstrates the potential application of Langmuir–Blodgett deposition for inorganic oxide film fabrication of thicknesses ranging from 0.1 to 40 nm.

沸騰無機酸中におけるTiの不働態と不働態表面の酸化膜について

沸騰無機酸中におけるTiの不働態と不働態表面の酸化膜について