White light-emitting diodes (WLEDs) are candidates to revolutionize the lighting industry towards energy efficient and environmental friendly lighting and displays. The current challenges in WLEDs encompass high luminous efficiency, chromatic stability, high colourrending index and price competitiveness. Recently, the development of efficient and low-cost downconverting photoluminescent phosphors for ultraviolet/blue to white light conversion was highly investigated. Here we report a simple route to design high-efficient WLEDs by combining a commercial ultraviolet LED chip (InGaAsN, 390 nm) and boehmite (g-AlOOH) hybrid nanoplates. Unusually high quantum yields (Z yield ¼ 38-58%) result from a synergic energy transfer between the boehmite-related states and the triplet states of the benzoate ligands bound to the surface of the nanoplates. The nanoplates with Z yield ¼ 38% are able to emit white light with Commission International de l'Eclairage coordinates, colour-rendering index and correlated colour temperature values of (0.32, 0.33), 85.5 and 6,111 K, respectively; overwhelming state-of-the-art single-phase ultraviolet-pumped WLEDs phosphors.

Following a computational-experimental approach, a highly luminescent b-diketonate-europium(III) complex containing 2-thenoyltrifluoracetonate (tta À ) and 5,6-epoxy-5,6-dihydro-[1,10] phenanthroline (ephen) ligands, Eu(tta) 3 ephen (II), was theoretically studied by DFT/TD-DFT calculations, synthesized from Eu(tta) 3 (H 2 O) 2 (I) and fully characterized by high resolution mass spectrometry, TGA analysis, vibrational, UV-Vis and photoluminescence spectroscopy. For intramolecular energy transfer analysis purpose, Ln(NO 3 ) 3 (ephen) 2 [Ln ¼ Eu (III), Gd (IV)] complexes were also synthesized and complexes I and III were theoretically studied. The organic-inorganic tri-ureasil matrix was used as a support for the immobilization of complex II and two hybrid samples were synthesized as a monolith (MtU5Eu-II) and as a thin film (FtU5Eu-II), characterized and its photoluminescence properties were compared with those of complex II. The photophysical properties of complex II benefit from the synergy between the excited-states of both ligands that create efficient energy transfer pathways to optimize the Eu 3+ sensitization contributing to the large emission quantum yield (82 AE 8%), which is one of the highest so far reported for solid lanthanide b-diketonate complexes. Moreover, although the incorporation of complex II into the hybrid matrix is disadvantageous from the quantum yield point of view, MtU5Eu-II and FtU5Eu-II exhibit the highest emission quantum yields reported so far for Eu 3+ -containing hybrids (63 AE 6% and 48 AE 5%, respectively). Additionally, a significant improvement in the photostability under UV irradiation of the incorporated complex II is observed. The possibility of FtU5Eu-II to be used as a luminescent solar concentrator was evaluated and an optical conversion efficiency of $9% as well as an ability to boost up the Si-photovoltaic cell output to 0.5% were verified.

The sol-gel preparation of a bridged silsesquioxane containing europium(III) salts and 2-thenoyltrifluoroacetone has been achieved from a new ethane tetracarboxamide-based organosilane. Free-standing films with thicknesses up to 440 μm and maximum absolute quantum yield (q) of 0.34 ± 0.03 (excitation at 320 nm) were prepared by the drop cast method, while thin films (∼200-400 nm) spin-coated on glass substrates led to highly luminescent coatings with q = 0.60 ± 0.02 (excitation at 345 nm). The thin films were tested as planar luminescent solar concentrators and the optimized device displays an optical conversion efficiency of 12.3% in the absorbing spectral region of the active layer (300-380 nm).