Chaoyou Tao

Pyridine-2,6-dicarboxylic acid for the sensitization of europium(III) luminescence with very long lifetimes

Convenient and mild syntheses of two europium(III) complexes, Na[Eu(dipic)2·3H2O]·4H2O (dipic = dipicolinate anions) and Na[Eu(dipic)2·phen]·H2O (phen = 1,10-phenanthroline), were reported. These two europium(III) complexes were confirmed by 1H NMR, FT-IR, UV-Vis spectroscopy, and elemental and lifetime analysis. Interestingly, the lifetimes were 2.31 ms and 2.38 ms for Na[Eu(dipic)2·3H2O]·4H2O in the solid state and in ethanol solution, respectively, though high-frequency vibrations were present in the first coordination sphere. Furthermore, the lifetime for Na[Eu(dipic)2·phen]·H2O in ethanol solution is 3.23 ms, which is the longest lifetime reported to date. The Na[Eu(dipic)2·phen]·H2O complexes exhibited a quantum yield of 36.1% in ethanol solution, which was longer than that of Na[Eu(dipic)2·3H2O]·4H2O. The value of the stimulated emission cross-section (σp) for Na[Eu(dipic)2·phen]·H2O in ethanol was very close to the values of the Nd-glass laser for practical use, which showed that it had potential application as a high-powered liquid laser medium.

Sol-gel preparation of moisture-resistant antireflective coatings from novel hollow silica nanoparticles

Abstract In this study, a simple approach was developed to prepare hollow silica nanoparticles (HSNs) sols via a one-step base-catalyzed sol–gel process using methyltriethoxysilane and tetraethoxysilicate as co-precursors. The prepared sols were suitable for large-area processing with ease of antireflective (AR) coating and being directly applicable without requiring any pre- or post-treatment. AR coatings were dip coated on K9 glasses from these sols. Furthermore, AR coatings were intrinsically hydrophobic with static water contact angles up to 126.5° on the smooth K9 glass. A particle growth mechanism of the hybrid HSNs was proposed, and the relationship between the microstructure of HSNs and the properties of AR coatings was investigated. These AR coatings with relatively excellent AR properties and improved moisture resistance were useful in solar cells, low-cost electronics, and optical devices.Graphical Abstract

Double-layer tri-wavelength hydrophobic antireflective coatings derived from methylated silica nanoparticles and hybrid silica nanoparticles

AbstractIn this paper, we reported the design and preparation of a double-layer antireflective (AR) coating, which possessed relatively high transmittance at 351, 527, and 1053 nm. The refractive indices and film thicknesses of the under layer and upper layer of the simulated AR coating were determined as 1.27, 95 nm and 1.18, 106 nm, respectively. The under layer of the double-layer coating dip-coated from a mixture of base-catalyzed and acid-catalyzed silica sols had a refractive index of 1.27. The upper layer fabricated by the deposition of methylated silica nanoparticles by simply adding methyltriethoxysilane into the base-catalyzed silica sols possessed a refractive index of 1.18. The hydrophobicity of coatings could be dramatically improved with the water contact angle increasing from 23.4° to 150.0°, and the refractive indices of the pure base-catalyzed silica coatings were easily decreased from 1.20 to 1.12 through the surface treatment of silica nanoparticles. Thus, we have successfully prepared a double-layer AR coating, which had a high transmittance of 99.8%, 96.1%, and 99.7% at 351, 527, and 1053 nm, respectively.

Synthesis, characterization and photoluminescent properties of europium(III) complexes with ligands bearing benzimidazole groups

Europium(III) complexes have attracted tremendous interests from scientists for their excellent properties and their important potential applications in the fields of organic light emitting diodes, biological labeling, laser media. In this paper, two novel europium(III) complexes having 2-thenoyltrifluoroacetylacetone (tta) as the first ligand and the second ligands bearing benzimidazole groups were synthesized and characterized by FT-IR, UV–Vis, 1H-NMR, and elemental analysis. The photoluminescent properties of complexes in the solid state, in ethanol solution and embedded in poly(methyl methacrylate) (PMMA) were investigated. All europium(III) complexes exhibited strong luminescent intensity, high quantum yields (Φ) and long luminescent lifetimes. The intrinsic luminescent quantum yields (ΦLN) and the stimulated emission cross-section (σp) of complexes were obtained based on the emission spectra and luminescent lifetimes of 5D0 excited state for europium(III) ion. All europium(III) complexes exhibited relatively high intrinsic luminescent quantum yields. In view of σp values, which are the same order as the values of Nd-glass laser for practical use, these europium(III) complexes may find potential applications in the field of high-power laser media.