Novel Hybrid Thin Film Luminescent Solar Concentrators

New robust luminescent solar concentrators were produced by growing Eu(TTA)3phen -containing parylene thin films on PMMA slabs through a novel co- deposition process. The optical measurements demonstrated that Eu(TTA)3phen -containing parylene exhibits higher absorption than the conventional Eu(TTA)3phen films and the luminescence peaks characteristic of Eu(TTA)3phen compound. This indicates that the Eu complex is not affected by the matrix interaction thus maintaining its extremely large Stokes shift. Moreover the parylene matrix improves the luminescence intensity of the films: in fact, under the same absorption these films show a luminescence intensity more than two times higher than standard Eu(TTA)3phen ones. The current-voltage (I-V) measurements show that the Eu(TTA)3phen -containing parylene LSCs produce a current density more than twice as high as conventional Eu(TTA)3phen ones with the same Eu(TTA)3phen quantity and that their efficiency decreases more than ten times slower than organic-based LSCs at increasing illuminating area, thus highlighting the feasibility of developing large size LSCs

Modulating the photoluminescence of europium-based emitting polymers: Influence of the matrix on the photophysical properties

A series of luminescent materials have been prepared by the ternary europium complex Eu(tta)3(phen) (tta = 2-thenoyltrifluoroacetonato, phen = 1,10-phenanotroline) embedded into different polymer matrixes (polystyrene, poly(vinyl difluoride), poly(acrylonitryle) and poly(methyl methacrylate)) in order to investigate the effect of the polymer on the luminescent properties of the hybrid materials. Fourier transform infrared spectra (FTIR), UV/vis spectra, scanning electron microstructure (SEM) and luminescent properties of the europium complex and the hybrid materials are described in detail. In all cases, interaction between the polymer and the europium complex was observed from the above techniques. This interaction was strong enough to lead to a variation in the photoluminescent properties of the hybrid films: while poly(vinyl difluoride) doped polymers showed a reduce quantum yield (φ = 24%), a dramatic/significant enhanced in this parameter (φ up to 73%) was observed for the other materials in comparison with the φ value of the precursor complex (30.5%). This result may support the conclusion that while some polymers could interact with the complex, act as antennae and transfer energy to the central Eu(III) ion, other quench the luminescence of the complex. Based on this high φ, these films could be applied in top optical applications such as light-emitting diodes and/or active polymer optical fibers. © 2013 Elsevier B.V

Highly efficient luminescent materials: Influence of the matrix on the photophysical properties of Eu(III) complex/polymer hybrids

Highly efficient luminescent materials based on the europium complex Eu(tta)3(phen) (tta = 2-thenoyltrifluoracetonato, Phen = 1,10-phenantroline) incorporated into different polymer matrixes (polyvinyl butyral, polysulfone and polyurethane) have been prepared. The photoluminescent hybrid films were prepared by solution mixing/drop casting which has been revealed as a very convenient method to prepare these polymeric materials because of the good homogeneous distribution of the Eu(III) complex into the polymer matrix. A detail analysis of the Fourier transform infrared spectra, UV/Vis spectra and photoluminescent properties is presented. These results agree with the conclusion that the polymer interact with the complex, act as antenna and transfer energy to the central Eu(III) ions. As a result of this interaction, the efficiencies of the doped films are dramatically enhanced (photoluminescence quantum yields in the range 58-86%) in comparison with that of the precursor complex. The luminescent Eu(tta)3(phen) complex-polymer hybrid materials developed in this study could be successfully applied in optical devices as polymer light-emitting diodes or active polymer optical fiber applications. © 2014 Elsevier B.V

Modulating the photoluminescence of europium-based emitting polymers: Influence of the matrix on the photophysical properties

A series of luminescent materials have been prepared by the ternary europium complex Eu(tta)3(phen) (tta = 2-thenoyltrifluoroacetonato, phen = 1,10-phenanotroline) embedded into different polymer matrixes (polystyrene, poly(vinyl difluoride), poly(acrylonitryle) and poly(methyl methacrylate)) in order to investigate the effect of the polymer on the luminescent properties of the hybrid materials. Fourier transform infrared spectra (FTIR), UV/vis spectra, scanning electron microstructure (SEM) and luminescent properties of the europium complex and the hybrid materials are described in detail. In all cases, interaction between the polymer and the europium complex was observed from the above techniques. This interaction was strong enough to lead to a variation in the photoluminescent properties of the hybrid films: while poly(vinyl difluoride) doped polymers showed a reduce quantum yield (φ = 24%), a dramatic/significant enhanced in this parameter (φ up to 73%) was observed for the other materials in comparison with the φ value of the precursor complex (30.5%). This result may support the conclusion that while some polymers could interact with the complex, act as antennae and transfer energy to the central Eu(III) ion, other quench the luminescence of the complex. Based on this high φ, these films could be applied in top optical applications such as light-emitting diodes and/or active polymer optical fibers. © 2013 Elsevier B.V

Highly efficient luminescent materials: Influence of the matrix on the photophysical properties of Eu(III) complex/polymer hybrids

Highly efficient luminescent materials based on the europium complex Eu(tta)3(phen) (tta = 2-thenoyltrifluoracetonato, Phen = 1,10-phenantroline) incorporated into different polymer matrixes (polyvinyl butyral, polysulfone and polyurethane) have been prepared. The photoluminescent hybrid films were prepared by solution mixing/drop casting which has been revealed as a very convenient method to prepare these polymeric materials because of the good homogeneous distribution of the Eu(III) complex into the polymer matrix. A detail analysis of the Fourier transform infrared spectra, UV/Vis spectra and photoluminescent properties is presented. These results agree with the conclusion that the polymer interact with the complex, act as antenna and transfer energy to the central Eu(III) ions. As a result of this interaction, the efficiencies of the doped films are dramatically enhanced (photoluminescence quantum yields in the range 58-86%) in comparison with that of the precursor complex. The luminescent Eu(tta)3(phen) complex-polymer hybrid materials developed in this study could be successfully applied in optical devices as polymer light-emitting diodes or active polymer optical fiber applications. © 2014 Elsevier B.V

An Autonomous Device for Solar Hydrogen Production from Sea Water

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Low-temperature UV-processing of nanocrystalline nanoporous thin TiO2 films : an original route toward plastic electrochromic sytems

The direct UV irradiation of nanoparticulate TiO2 films deposited by the “doctor-blade” technique led to 1.1 μm thick nanoporous and nanocrystalline anatase layers on various kinds of substrates as evidenced by various characterization techniques (MET, SEM, XRD, TGA-MS, and N2 sorption measurements). These films demonstrated high electrochromic responses and coloration efficiencies in an ionic liquid containing a lithium salt, which is a stable and environmental friendly electrolyte. The coloration efficiency reached 38 cm2 C−1 for films on ITO/plastic, for a 0.65 absorption change at 710 nm, whereas the corresponding film on FTO/glass showed a 40 cm2 C−1 coloration efficiency for a 1.1 absorbance change at 710 nm. The high surface area, nanoporous texture, and nanoparticulate structure of these layers provide a large number of intercalation sites, and minimal diffusion path lengths are ensured by the high surface-to-volume ratio

Low-Temperature UV Processing of Nanoporous SnO2 Layers for Dye-Sensitized Solar Cells

Connection of SnO2 particles by simple UV irradiation in air yielded cassiterite SnO2 porous films at low temperature. XPS, FTIR, and TGA-MS data revealed that the UV treatment has actually removed most of the organics present in the precursor SnO2 colloid and gave more hydroxylated materials than calcination at high temperature. As electrodes for dye-sensitized solar cells (DSCs), the N3-modified 1−5 μm thick SnO2 films showed excellent photovoltaic responses with overall power conversion efficiency reaching 2.27% under AM1.5G illumination (100 mW cm−2). These performances outperformed those of similar layers calcined at 450 °C mostly due to higher Voc and FF. These findings were rationalized in terms of slower recombination rates for the UV-processed films on the basis of dark current analysis, photovoltage decay, and electrical impedance spectroscopy studies