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Solid state lighting (SSL) revolutionized the light sources and displays market. Challenges include the seek for low cost and efficient materials able to emit pure colours (red, green and blue). Herein, we report amine-functionalized organic/inorganic di-ureasil hybrids consisting of a siliceous skeleton and oligopolyether chains, d-U(600), modified by distinct concentration values of a blue emitting uncharged polyfluorene (poly (9,9-dioctylfluorene)-co-phenylene) (PF). Structural and thermal studies reveal that the interaction between the PF and the d-U(600) yield to an enhancement of the PF thermal stability. The optical characterization shows that the emission is strongly dependent on the excitation energy presenting a red-shift as the excitation wavelength increases, enabling a fine tuning of the emission colour coordinates. Under UV excitation, a maximum emission quantum yield value 0.44 ± 0.04 was attained, which is remarkably higher when compared to the value found for the undoped d-U(600), 0.13 ± 0.01, an analogous to the value found for the isolated PF, pointing out that the incorporation into the hybrid host did not yield to an emission efficiency quenching. A commercial LED chip emitting at 365 nm was coated by the PF-doped d-U(600) showing a wall-plug efficiency of 0.04% and a luminous efficacy of 0.003 lm⋅W−1, demonstrating the applicability of these materials as blue-emitting phosphors to be applied in SSL. Image 1 [ABSTRACT FROM AUTHOR]

Abstract: Organic–inorganic hybrids containing luminescent lanthanide complex Eu(tta)3phen (tta=thenoyltrifluoroaceton, phen=1,10-phenanthroline) and silver nanoparticles have been prepared via mixing rare earth complex and nanoparticles with the precursors of di-ureasil using a sol–gel process. The obtained hybrid materials with transparent and elastomeric features were characterized by transmission electron microscope, solid-state 29Si magic-angle spinning NMR spectra, diffuse reflectance, UV-visible absorption and photoluminescence spectroscopies. The effect of the silver nanoparticles on the luminescence properties was investigated. The experimental results showed that the luminescence intensity of the Eu(tta)3phen complex could be enhanced by less than ca. 9.5nM of silver nanoparticles with the average diameter of 4nm, and reached its maximum at the concentration of ca. 3.6nM. Further increasing the concentration of the silver nanoparticles (>9.5nM) made the luminescence quenched. The enchancement and quench mechnism was discussed. [Copyright &y& Elsevier]

Abstract: Poly(oxyethylene) (POE)/siloxane-based materials incorporating magnesium triflate (Mg(CF3SO3)2) were synthesized by the sol–gel process. The host Class II hybrid matrix (di-ureasil) employed is composed of a siliceous framework to which short POE chains are covalently bonded through urea linkages. Ormolytes with salt composition n (molar ratio of oxyethylene moieties per Mg2+ ion) ranging from ∞ to 1 were investigated. The nanohybrid with n =20, which is thermally stable up to 360 °C, exhibits the highest conductivity (e.g., approximately 4.0×10−6 and 6.7×10−5 S cm−1 at 35 and 104 °C, respectively). The redox stability domain of this material spans from −3.0 to +2.0 V vs. Mg/Mg2+. [Copyright &y& Elsevier]

Light-emitting diodes (LEDs) are replacing conventional lighting sources, like incandescent and fluorescent lamps, due to their higher efficiency, lower energy consumption and environmental friendliness characteristics. Additional applications envisaging "engineered light" able to control the human circadian rhythm are now in place with emphases on green-emitting LEDs. In this work, transparent and flexible coatings based on organic–inorganic di-ureasil hybrids doped in-situ with a terbium (Tb3+) complex involving salicylic acid as ligands were synthesized. The materials are transparent, essentially amorphous and thermal stable up to 180 °C. Under near-UV excitation, bright green emission with high quantum yield (0.565 ± 0.057) and enhanced photostability are observed. Green-emitting prototypes were fabricated using a commercial near-UV-emitting LED (NUV-LED) combined with the Tb3+-doped di-ureasil coating showing narrow-band green emission with yellowish-green color coordinates (Commission Internationale de l'Éclairage, CIE 1931) of (0.329, 0.606) and high luminous efficacy (21.5 lm/W). This efficacy is the largest one reported for analogous prototypes formed by an NUV-LED coated with a green-emitting phosphor prepared under mild synthetic conditions (<100 °C), demonstrating that in-situ formation of carboxylate lanthanide-based complexes is an energy saving process with potential for solid-state lighting and backlight for flexible displays. Image 1 • High doping concentration of Tb3+ carboxylate-based di-ureasil hybrids. • Tb3+-doped di-ureasils with a high emission quantum yield (0.565 ± 0.057). • "π-stacking" of aromatic ligands benefits near-UV excitation. • High luminous efficacy (21.5 lm/W) of 365 nm yellowish-green LED coated with the hybrids. [ABSTRACT FROM AUTHOR]