Luminescent film with terbium-complex-bridged polysilsesquioxanes

A luminescent film with terbium-complex-bridged polysilsesquioxanes has been prepared by sol-gel processing of a new bifunctional monomer that combines the role of a sol-gel molecular precursor with a Tb3+ ion coordinate donor. The emission from Tb3+ ion due to ligand-to-metal energy transfer was observed by UV excitation.

Luminescence properties of LB films based on heteropolytungstate of rare earth

In this work, the LB films based on heteropolytungstate of Dy and Sm have been prepared. The X-ray diffraction shows the LB films have a highly ordered lamella structure. The luminescence characteristics of the LB films were studied. The charge transfer bands of LB films are in higher energies than those of the corresponding solids. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ in the LB films is different from that of the solid. The differences in the spectra show that the Dy3+ site symmetry in LB film was changed due to the interaction between the surfactant and the polyanions. The differences could also be found in the luminescence spectra of the LB films of Sm complex.

Langmuir-Blodgett films based on europium-substituted heteropolytungstate and their luminescence properties

Several new hybrid organic-inorganic Langmuir-Blodgett (LB) films containing europium-substituted hetero-polytungstate Eu (XW11O39)(2)''(-) (X=Ge, Si, B) were successfully obtained using LB technique. When the heteropolytungstate anions are dissolved in the subphase, dimethyldioctadecylammonium bromide compression isotherms have been modified, which shows that the polyanions interact with the monolayer. Y-type LB films were obtained from the systems. Low-angle X-ray has shown that these LB films have well-defined lamella. The LB films were characterized by luminescence spectra and the characteristic luminescence behavior for europium-substituted heteropolytungstate complexes and their LB films were discussed. The results of excitation spectra indicate that the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency could be greatly increased. The results of luminescence spectra indicate that the formations of hybrid organic-inorganic LB films have a great effect on the luminescence of europium-substituted heteropolytungstate. The lifetime shortening was observed in LB films.

Synthesis of the complex fluoride LiBaF3 and optical spectroscopy properties of LiBaF3 : M(M = Eu,Ce) through a solvothermal process

The complex fluoride LiBaF3 and LiBaF3:M(M = Eu, Ce) is solvothermally synthesized at 180 degreesC and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy. In the solvothermal process, the solvents, molar ratios of initial mixtures and reaction temperature play important roles in the formation of products. The excitation and emission spectra of the LiBaF3:M(M= Eu,Ce) have been measured by fluorescence spectrophotometer. In the LiBaF3: Eu emission spectra, there is one sharp line emission located at 360 nm arising from f --> f transition of Eu2+ in the host lattice, and typical doublet 5d-4f emission of Ce3+ in LiBaF3 powder is shown.

Growth and vibrational spectra of doped KMgF3 single crystal

The different ions doped KMgF3 single crystals are prepared by the vertical Bridgman method. The near-infrared absorption spectra for different parts of all as-growth crystals indicate that there is the best transparency in middle part. The correlation between the vibronic frequencies of Eu2+ and the site displacement of Cu+ co-doped ions is firstly studied, which indicates that Cu+ ions replace the site of the Mg2+ ions. The co-doped Eu2+ counteracts the charge misfit causing by the replacement of Mg2+ with Cu+. The overlapping of the emission spectra of the Eu2+ and the excitation spectra of the Cu+ results in the energy transfer from Eu2+ to Cu+.

Luminescent hybrid films obtained by covalent grafting of terbium complex to silica network

Luminescent hybrid thin films consisting of terbium complex covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. A new monomer, N-(4-benzoic acid-yl), N'-(propylthiethoxysilyl)urea (PABI), has been synthesized by grafting isocyanatopropyltriethoxysilane (ICPTES) to p-aminobenzoic acid and characterized by H-1 NMR IR and MS, The monomer acts as a ligand for Tb3+ ion and as a sol-gel precursor. Band emission front Tb3+ ion due to an efficient ligand-to-metal energy transfer was observed by UV excitation. The decay curves of Tb3+ in the hybrid films were measured. The energy difference between the triplet state energy of PABI and the D-5(4) level of Tb3+ ion falls in the exciting range to sensitize Tb3+ ion fluorescence.

Luminescence properties of rare earth-polyoxometalate thin film deposited by sol-gel process

The rare earth (Eu3+, Dy3+)-polyoxometalate thin films were fabricated on quartz plate by the sol-gel method. The thin films were demonstrated by the luminescence spectra. The thin films exhibit the characteristic emission bands of the rare-earth ions. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ and the red to orange ratio (R:O) of Eu3+ in the films are different from that of the corresponding solids. Furthermore, the thin films present shorter fluorescence lifetime than the pure complexes. The reasons that were responsible for these results were also discussed.

Sol-gel derived silicate oxyapatite phosphor films doped with rare earth ions

Rare-earth (Eu3+, Tb3+)-doped Ca2Y8(SiO4)(6)O-2 luminescent thin films were dip-coated on silicon and quartz glass substrates through a sol-gel route. X-ray diffraction (XRD), scanning electron microscopy (SEM) and luminescence excitation and emission spectra as well as luminescence decays were used to characterize the resultant films. The results of XRD reveal that these films remain amorphous below 700 degreesC, begin to crystallize at 800 degreesC, and crystallize completely around 1000 degreesC with an oxyapatite structure. The grain structure of the film can be seen clearly from SEM micrographs, where particles with various shape and average size of 250 nm can be resolved. The Eu3+ and Tb3+ ions show their characteristic red (D-5(0)-F-7(2)) and green (D-5(4)-F-7(5)) emission in the films with a quenching concentration of 10 and 6 mol% (of Y3+), respectively. The lifetime of Eu-3divided by increases with the heat treatment temperature front 700 to 1100 degreesC.

Luminescence properties of transparent hybrid thin film covalently linked with lanthanide complexes

Novel hybrid thin films covalently doped with Eu3+ (Tb3+) have been prepared via direct routes involving co-condensation of tetraethoxysilane and phen-Si in the presence of Eu3+ (Tb3+) by spin-casting and their luminescence properties have been investigated in detail. Lanthanide ions can be sensitized by anchored phenanthroline in hybrid thin films. Excitation at the ligand absorption wavelength (272 nm) resulted in the strong emission of the lanthanide ions i.e. Eu3+ D-5(0)-F-7(J) (J=0, 1, 2, 3, 4) emission lines and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) due to the energy transfer from the ligands to the lanthanide ions.

Study on highly ordered luminescent Langmuir-Blodgett films of heteropolytung state complexes containing lanthanide

Luminescent thin films of heteropolytungstate complexes containing lanthanide (europium or samarium) were successfully fabricated by the Langmuir-Blodgett (LB) technique. The pressure-area isotherm of the monolayer of dimethyldioctadecylammonium. bromide (DODA) is modified rather markedly when the subphase contains the complex of Na9EuW10O36 or Na9SmW10O36. The above results indicate that the monolayer of DODA has a strong interaction with the polyanions of EuW10O369-. (or SmW10O369-). X-ray photoelectron spectra and fluorescent spectra verify that europium and tungsten atoms are 36 36 incorporated into the LB films. Ultraviolet (UV), fluorescent spectra and low-angle X-ray diffraction experiments demonstrate that these LB films have a well-defined lamellar structure. The LB film containing EuW10O369- can give off strong fluorescence 16 on UV irradiation. The characteristic emission behaviors of europium ions in LB films and in the powder of Na9EuW10O369- are discussed. It is found that the intensity ratio of the D-5(0)-F-7(2) transition to the D-5(0)-->F-7(1) transition in LB film is quite different from that in the powder of Na9EuW10O36. The difference of the ratio indicates that the site symmetry of europiurn is distorted in LB film, which is probably due to the strong electrostatic interactions between DODA and polyanions.

Phenanthroline-functionalized MCM-41 doped with europium ions

Organo-functionalized MCM-41 containing non-covalently linked 1,10-phenanthroline (denoted as Phen-MCM-41) was synthesized by template-directed co-condensation of tetraethoxysilane and the modified phenanthroline (denoted as Phen-Si). XRD, FTIR, UV/VIS spectroscopy as well as luminescence spectroscopy were employed to characterize Phen-MCM-41. No disintegration or loss of the Phen-Si during the solvent extraction procedure could be observed. When monitored by the ligand absorption wavelength (272 nm), the undoped MCM-41 produces a broad band emission centered at 450 run, whereas europium (III) doped Phen-MCM-41 displays the emission of the Eu3+, i.e., D-5(0) --> F-7(J) (J = 0, 1, 2, 3, 4) transition lines due to the energy transfer from the ligands to Eu3+ as well as a broad band emission centered at 442 nm.

Preparation and luminescence properties of hybrid materials containing europium(III) complexes covalently bonded to a silica matrix

A new kind of luminescent organic-inorganic hybrid material (denoted Hybrid I) consisting of europium 1,10-phenanthroline complexes covalently attached to a silica-based network was prepared by a sol-gel process. 1,10-Phenanthroline grafted to 3-(triethoxysilyl)propyl isocyanate was used as one of the precursors for the preparation of an organic-inorganic hybrid materials. For comparison purposes, the hybrid material (denoted Hybrid II) in which phenanthroline was not grafted onto the silica backbone of the frameworks was also prepared. Elemental analysis; NMR, FT-IR, UV/vis absorption, and luminescence spectroscopies, and luminescence decay analysis were used to characterize the obtained hybrid materials. It is shown that the homogeneity of Hybrid I is superior to that of Hybrid II, and a higher concentration europium can be incorporated into Hybrid I than Hybrid II. Excitation at the ligand absorption wavelength (283 nm) resulted in the strong emission of the Eu3+ D-5(0)-F-7(J) (J = 0-4) transition lines as a result of the efficient energy transfer from the ligands to the EU3+ in Hybrid I. The number of water molecules coordinated to the europium ion was estimated, and the structure of the as-synthesized Hybrid I was predicted on the basis of the experimental results.

Vacuum ultraviolet optical properties of (La,Gd)PO4 : RE3+ (RE = Eu, Tb)

Vacuum ultraviolet excitation spectra of phosphors (La,Gd)PO4:RE3+ (RE = Eu or Tb) and X-ray photoelectron spectra of LaPO4 and GdPO4 are investigated. The vacuum ultraviolet excitation intensity of (La,Gd)PO4:RE3+ is enhanced with the increasing of Gd3+ content, which implies that Gd3+ plays an intermediate role in energy transfer from host absorption band to RE3+. When Gd3+ is doped into LaPO4:Eu, charge transfer band (CT band) begins to shift to higher energy region and the overlap degree of CT band and the host absorption band gets greater with more Gd3+ doped into LaPO4. These results suggest that the dopant (Gd3+) gives an important influence on energy transfer efficiency. The top of LaPO4 valance band is formed by the 2p level of O2-, whereas that of GdPO4 valance band is formed by the 2p level of O2- and the 4f level of Gd3+, showing the differences in band structures between LaPO4 and GdPO4.

Fabrication, patterning, and optical properties of nanocrystalline YVO4 : A (A = Eu3+, Dy3+, Sm3+, Er3+) phosphor films via sol-gel soft lithography

Nanocrystalline YVO4:A (A = Eu3+, Dy3+, Sm3+, Er3+) phosphor films and their patterning were fabricated by a Pechini sol-gel process combined with soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy (AFM) and optical microscopy, UV/vis transmission and absorption spectra, photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 400 degreesC and the crystallinity increased with the increase of annealing temperatures. Transparent nonpatterned phosphor films were uniform and crack-free, which mainly consisted of grains with an average size of 90 nm. Patterned gel and crystalline phosphor film bands with different widths (5-60 mum) were obtained. Significant shrinkage and a few defects were observed in the patterned films during the heat treatment process. The doped rare earth ions (A) showed their characteristic emission in crystalline YVO4 phosphor films because of an efficient energy transfer from vanadate groups to them. The Sm3+ and Er3+ ions also showed upconversion luminescence in a YVO4 film host. Both the lifetimes and PL intensity of the rare earth ions increased with increasing annealing temperature from 400 to 800 degreesC, and the optimum concentration for Eu3+ was determined to be 7 mol % and those for Dy3+, Sm3-, and Er3+ were 2 Mol % of Y3- in YVO4 films, respectively.

A novel way to enhance electroluminescence performance based on soluble binary and ternary europium 1,1,1-trifluoroacetylacetonate

Five rare earth complexes (Gd(acae)(3), Gd(TFacaC)(3), Eu(acaC)(3), Eu(TFacaC)(3) and Eu(TFacaC)(3)bipy; acac, acetylacetone; TFacac, 1,1,1-trifluoroacetylacetone; bipy, 2,2'-bipyridyl) were synthesized. By comparing the phosphorescence spectra of Gd(acac)(3) and Gd(TFacac)(3) the effect of the replacement of hydrogen by fluorine was examined. Organic light-emitting devices (OLEDs) based on the corresponding europium complexes as emissive layers were also fabricated by the spin-coating method. The triple-layer-type device with the structure glass substrate/ITO (indium-tin oxide)/PVK [poly(N-vinylcarbazole)]/(PVKEu)-Eu-.(TFacac)(3)bipy:PBD[2-(4-bibipyyl)-5-(4-t-butylbipyl-1,3,4-oxadiazole)]/PBD/Al (aluminum) exhibits a brighter red luminescence than those devices with Eu(acac)(3) and Eu(TFacac)(3) complexes as emissive centers upon applying a d.c. voltage.