Tetsuro Jin

Preparation and luminescence characteristics of the europium and terbium complexes incorporated into a silica matrix using a sol–gel method

Abstract A series of silica-based composite materials incorporating lanthanide bipyridyl (bpy) and phenanthroline (phen) complexes, SiO 2 :Ln(bpy) 2 3+ and SiO 2 :Ln(phen) 2 3+ (Ln=Eu, Tb), was prepared by the sol–gel method with luminescence properties studied before and after heat treatment up to 873xa0K. For the SiO 2 :Ln(bpy) 2 3+ and SiO 2 :Ln(phen) 2 3+ composites heated at appropriate temperatures, the energy transfer from the bpy or phen ligands to Ln 3+ ions took place smoothly, as for the original complexes, and consequently strong red or green emissions based on Eu 3+ and Tb 3+ ions were observed. Emission outputs from the lanthanide complexes incorporated into silica gel matrices were intensified by optimizing the concentration of complexes and heat treating at individual temperatures, and the maximum relative emission intensities (vs. Y(P,V)O 4 :Eu and LaPO 4 :Ce,Tb phosphors, as practically used) were ca. 15% and 45% for SiO 2 :Eu(phen) 2 3+ and SiO 2 :Tb(bpy) 2 3+ composite materials. Furthermore, thermal stability of Ln(bpy) 2 3+ complexes was effectively improved compared with the original lanthanide complexes by incorporation into an SiO 2 matrix.

Luminescence properties of lanthanide complexes incorporated into sol-gel derived inorganic-organic composite materials

Abstract Lanthanide complexes such as [Tb(bpy) 2 ]Cl 3 and [Eu(phen) 2 ]Cl 3 incorporated into the organically modified silicates (ormosil) were prepared and their luminescence properties measured. The ormosil composite materials incorporated with [Tb(bpy) 2 ]Cl 3 and [Eu(phen) 2 ]Cl 3 had green and red emissions and, by optimization of the complex concentration amounts and heat treatment conditions, they provided emission intensities with 100 and 80%, respectively, of those for conventional phosphors used as lamp illumination. The resulting composite materials also possessed excellent mechanical strength, hydrolytic stability, and, consequently good durability for the emissions from the lanthanide compositions after being exposed to laboratory atmosphere for 100 days.

Photovoltaic Cell Characteristics of Hybrid Silicon Devices with Lanthanide Complex Phosphor‐Coating Film

Conversion efficiency values of silicon photovoltaic cells were significantly enhanced, by surface coating of the organically modified silicate (ORMOSIL) composite phosphor films incorporating europium(III) phenanthroline and terbium(III) bipyridine complexes. Relative maximal outputs of the coated single-crystal (c-Si) and amorphous silicon (a-Si) photovoltaic devices compared with those of the uncoated c-Si and a-Si ones were increased to 118 and 108%, respectively, by optimizing for the complex concentration of the ORMOSIL composite films under air mass 1.5 (100 mW/cm{sup 2}), owing to the effective optical conversion from the ultraviolet fraction of sunlight to visible lights by the lanthanide complexes incorporated into the ORMOSIL matrix.

Luminescence Property of the Terbium Bipyridyl Complex Incorporated in Silica Matrix by a Sol‐Gel Method

Slica-based composite materials incorporated with a terbium bipyridyl complex, SiO 2 :Tb(bpy) 2 3- , were prepared by a sol-gel method. The thermal stability of Tb(bpy) 2 3+ was improved by incorporation into the silica matrix, and its green emissiom lines were intensified by heat-treatments under appropriate temperature conditions. These results demonstrate that the composite materials such as SiO 2 :Tb(bpy) 2 3+ possess potential as efficient phosphors.

Luminescence Characteristics of the Lanthanide Complex Incorporated into an ORMOSIL Matrix Using a Sol‐Gel Method

Composite materials prepared by the incorporation of terbium bipyridyl complex into hybrid-type matrices, containing inorganic and organic oligomers, so-called ORMOSIL, were prepared by the sol-gel method and their luminescence property was studied. The resulting ORMOSIL: Tb(bpy){sub 2}{sup 3+} composite materials provided a strong green emission which was intensified upon elevating the temperature. In particular, the same emission intensity value as that of the LaPO{sub 4}:Ce, Tb was observed for a composite material with 10 mole percent (m/o) of the complex, ORMOSIL:Tb(bpy){sub 2}{sup 3+} (10 m/o), after heating at 150 C in air.

Luminescence properties of lanthanide complexes and their silica-based composites

Abstract The spectroscopic properties of lanthanide complexes, [Eu(phen) 2 ]Cl 3 and [Tb(bpy) 2 ]Cl 3 (bpy=2,2′-bipyridine and phen=1,10-phenanthroline), as well as their composites incorporating them into some silica-based vitreous matrices prepared by a sol–gel method, have been characterized by measurements of emission spectra, lifetimes and quantum yields. Furthermore, their emission intensity variations were discussed on the basis of the symmetry around the lanthanide(III) ion and the non-radiative relaxation via water molecules in the lanthanide complex followed by some deductions on the high-performance luminescence characteristics of the anhydrous lanthanide complexes and their composites with the silica-based vitreous matrices.

Synthesis of Eu-doped photoluminescent titania nanotubes via a two-step hydrothermal treatment

In this work, the synthesis of Eu-doped titania nanotubes was studied via a two-step hydrothermal treatment method. The first hydrothermal treatment was to obtain Eu-doped TiO2 nanopowders with good dispersity. The second treatment was to produce the corresponding nanotubes. X-ray diffraction confirmed that the nanotubes were made of hydrated titania. Scanning electron microscope and transmission electron microscope analyses showed that the multilayered nanotubes had an outer diameter of 12 nm and inner diameter of 4 nm, with length up to a few microns. The Eu-doped nanotubes exhibited strong emission lines associated with the transition of Eu3+. The nanotubes prepared by the two-step hydrothermal treatment exhibited better photoluminescence properties than the corresponding nanopowders and nanotubes prepared directly by the one-step hydrothermal treatment. The effect of the heat treatment of nanotubes was also studied.