Efficient spectrally dynamic blue‐to‐green emission of bipyridine‐based bridged silsesquioxanes for solid‐state lighting

Nobre, Sónia S.; Cattoën, Xavier; Ferreira, Rute A. S.; Man, Michel Wong Chi; Carlos, Luı́s D.

doi:10.1002/pssr.200903396

Cited by 19 publications

(28 citation statements)

References 16 publications

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“…30,31 From the point of view of materials science, the main challenge in solid-state lighting is the development of novel phosphors that collect the blue light from long UV/blue LEDs and efficiently convert it into the other colours needed for white light emission. The phosphors should, therefore, display the following requests:…”

Section: Hybrids For Lightingmentioning

confidence: 99%

Progress on lanthanide-based organic–inorganic hybrid phosphors

et al. 2011

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Research on organic-inorganic hybrid materials containing trivalent lanthanide ions (Ln 3+ ) is a very active field that has rapidly shifted in the last couple of years to the development of eco-friendly, versatile and multifunctional systems, stimulated by the challenging requirements of technological applications spanning domains as diverse as optics, environment, energy, and biomedicine. This tutorial review offers a general overview of the myriad of advanced Ln 3+ -based organic-inorganic hybrid materials recently synthesised, which may be viewed as a major innovation in areas of phosphors, lighting, integrated optics and optical telecommunications, solar cells, and biomedicine.

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Section: Hybrids For Lightingmentioning

confidence: 99%

Progress on lanthanide-based organic–inorganic hybrid phosphors

et al. 2011

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“…A low-relative intensity band between 360 and 450 nm (more evident in the excitation spectrum of M-Eu) is also discerned. While the low-wavelength region (240 to 360 nm) is related to the excited states of the bpy-ligands, [14,21,25] the high-wavelength one (360 to 450 nm) is associated with the excited states of the NH=C¼O groups and of the siliceous nanoclusters, [22][23][24] as shown in the excitation spectra monitored within the hybrid emission (Fig. 7).…”

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confidence: 97%

“…6) and in a urea-bpy bridged silsesquioxane derived from the same precursor under different nucleophilic conditions. [21] Time-resolved experiments demonstrated that this emission is ascribed to a superposition of three distinct components: i) bpy triplet state (at ca. 450 nm, room temperature lifetime of 10 À5 -10 À4 s); electron-hole recombinations originated in the ii) NH=C¼O groups of the urea cross-linkages (ca.…”

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Lanthanide-Containing 2,2′-Bipyridine Bridged Urea Cross-Linked Polysilsesquioxanes

Nobre

Ferreira

Cattoën

et al. 2010

Spectroscopy Letters

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Urea-based bis-silylated 2,2 0 -Bipyridine (bpy) organic-inorganic hybrids incorporating different lanthanide (Ln 3þ ) ions (Eu 3þ , Gd 3þ , Tb 3þ or Eu 3þ =Tb 3þ ) were obtained by the sol-gel process. The structure and the emission characteristics of the hybrids were ascertained using X-ray diffraction, nuclear magnetic resonance, Fourier transform infrared spectroscopy, photoluminescence, and quantum yield measurements. The hybrids feature both the emission of the host and the Eu 3þ and=or Tb 3þ transitions allowing a fine-tuning of the color from the blue to the red, orange, or green spectral regions. Bpy-to-Ln 3þ and Tb 3þ -to-Eu 3þ energy transfer mechanisms are demonstrated and the hybrids present slightly distinct Ln 3þ coordination spheres due to the different bpy=Ln 3þ ratios.

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“…The spectra were collected over the 3200À300 cm À1 range by averaging 200 scans at a maximum resolution of 4 cm À1 . Curve-fitting procedures: To evaluate broad FT-IR and FTRaman bands and to identify underlying spectral components, the iterative least-squares curve-fitting procedure in PeakFit (version 4) 25 was used. The best fit of the experimental data was obtained by varying the frequency, bandwidth, and intensity of the bands and by using Gaussian/Voight shapes.…”

Section: Scheme 1 Synthetic Scheme Of the Reactionmentioning

confidence: 99%

“…15,16 When the synthetic procedure used to prepare L12 was adopted and Eu 3+ ions were incorporated (introduced as europium chloride (EuCl 3 )) (molar ratio P12/H 2 O/HCl/EuCl 3 = 1:600:0.2:x, where x = 0.05, 0.95, and 2.9), a photoluminescent lamellar BS (Eu@L12) was formed. 15 The combination of NH 4 16 The influence of the type of solvent was emphasized more recently. 17 When the synthetic route employed to prepare L12 was combined with the incorporation of a large excess of dimethylsulfoxide (DMSO) (molar ratio P12/H 2 O/DMSO/ HCl = 1:527:388:0.175), a material with a microsphere-like shape that mimics sea sponges was produced (L12D).…”

Section: Introductionmentioning

confidence: 99%

Self-Structuring of Lamellar Bridged Silsesquioxanes with Long Side Spacers

Fernandes

Nobre

et al. 2011

J. Phys. Chem. B

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International audienceDiurea cross-linked bridged silsesquioxanes (BSs) C10CnC10 derived from organosilane precursors, including decylene chains as side spacers and alkylene chains with variable length as central spacers (EtO)3Si (CH2)10 Y (CH2)n Y (CH2)10 Si(OEt)3 (n = 7, 9 12; Y = urea group and Et = ethyl), have been synthesized through the combination of self-directed assembly and an acid-catalyzed sol gel route involving the addition of dimethylsulfoxide (DMSO) and a large excess of water. This new family of hybrids has enabled us to conclude that the length of the side spacers plays a unique role in the structuring of alkylene-based BSs, although their morphology remains unaffected. All the samples adopt a lamellar structure. While the alkylene chains are totally disordered in the case of the C10C7C10 sample, a variable proportion of all-trans and gauche conformers exists in the materials with longer central spacers. The highest degree of structuring occurs for n = 9. The inclusion of decylene instead of propylene chains as side spacers leads to the formation of a stronger hydrogen-bonded urea urea array as evidenced by two dimensional correlation Fourier transform infrared spectroscopic analysis. The emission spectra and emission quantum yields of the C10CnC10 materials are similar to those reported for diurea cross-linked alkylene-based BSs incorporating propylene chains as side spacers and prepared under different experimental conditions. The emission of the C10CnC10 hybrids is ascribed to the overlap of two distinct components that occur within the urea cross-linkages and within the siliceous nanodomains. Time-resolved photoluminescence spectroscopy has provided evidence that the average distance between the siliceous domains and the urea cross-links is similar in the C10CnC10 BSs and in oxyethylene-based hybrid analogues incorporating propylene chains as side spacers (diureasils), an indication that the longer side chains in the former materials adopt gauche conformations. It has also allowed us to demonstrate for the first time that the emission features of the urea-related component of the emission of alkylene-based BSs depend critically on the length of the side spacers

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Efficient spectrally dynamic blue‐to‐green emission of bipyridine‐based bridged silsesquioxanes for solid‐state lighting

Cited by 19 publications

References 16 publications

Progress on lanthanide-based organic–inorganic hybrid phosphors

Progress on lanthanide-based organic–inorganic hybrid phosphors

Lanthanide-Containing 2,2′-Bipyridine Bridged Urea Cross-Linked Polysilsesquioxanes

Self-Structuring of Lamellar Bridged Silsesquioxanes with Long Side Spacers

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