In this work, we report the synthesis of TiO2 photoelectrodes sensitized with different natural organic dyes extracted (using methanol) from spinach, raspberry and passion fruit for their application ...in Dye-Sensitized Solar Cells (DSSC). The effects of Lead Sulfide (PbS) NanoParticles (NPs) doping on the sensitized TiO2 photoelectrodes photovoltaic performance were mainly studied. Good absorption in the visible range (400–700 nm) was observed for natural dyes extracted from spinach and raspberry, observing characteristic peaks associated with chlorophylls, β-carotenes and phycoerythrin pigments. On the other hand, natural dye synthesized from passion fruit showed a poor absorption in this range concerning the previous mentioned sources. Cells using spinach and raspberry based dyes generally showed good Fill Factors (FF) higher than 55%, observing depreciable or negative influence of the PbS doping. Open-Circuit voltages (Voc), Short-Circuit current densities (Jsc) and Power Conversion Efficiencies (PCE) in the range of 0.35–0.55 V, 0.01–0.12 mA/cm2 and 0.002–0.03 % were respectively estimated.
•Natural organic dyes were synthesized from spinach, raspberry and passion fruit.•Spinach and raspberry dyes showed considerable optical absorption in visible range.•DSSCs presented high fill factors (>55 %) by using spinach and raspberry dyes.•PbS-NPs doping depreciably or negatively affected the photovoltaic performance.•Results suggest possible incompatibilities between PbS-NPs and natural dyes.
We study the mechanical properties of Cu thin films on Si (100) by performing nano-indentation using an atomic force microscopy. Cu films with thickness of 0.3 µm, 1 µm and 2 µm were analyzed. Area ...profile studies let us understand the critical influence of the indenter geometry uncertainty on the estimation of the mechanical properties. This seems to be very important when studying thin films because penetrations depths are very small and close to the indenter apex which could have geometrical discontinuities. We found that the hardness of the samples and Young modulus decreases as the film thickness increases. The origin of this behavior could be ascribed to a substrate-film mechanical coupling or a microstructural effect.
Noble metal-based Photonic Crystals (PCs) have emerged as outstanding candidates for precise light management, projecting applications in strategic areas for society like high-sensitivity and fast ...molecular (inorganic/organic/bio) sensing by Surface-Enhanced Raman Spectroscopy (SERS). In this work, we report an exhaustive study on the potential of large-scale (active area >1 cm2) Au nanodisks-based 2D PCs fabricated by single-beam Laser Interference Lithography (LIL) for high-performance SERS molecular sensing. This technique was used to fabricate periodic nanoarrays (period of 470 nm) of Au nanodisks with thicknesses from 50 up to 125 nm. The period was chosen following Finite-Difference Time-Domain (FDTD) simulations that suggested the best electric-near field enhancement for this condition. Confocal Raman microscopy and Methylene Blue (MB) as active Raman marker, were used to assess the samples' performance for molecular sensing. SERS studies have shown that the nanodisks' thickness can be a considerable size parameter for the Raman signal amplification, observing higher signal enhancements for higher thicknesses. The observed thickness effects on the Raman signal enhancement were consistent with FDTD simulations, which predicted higher electric-near field amplifications for higher thickness within the red/near-infrared range. Results show that our PCs enable to measure the characteristic Raman footprint of the analyte with good spectral resolution using relatively low powers (0.04–1 mW) and short acquisition times (1–30 s), considering an MB surface mass density as low as 2.6 ng/cm2. SERS enhancement factors as high as 2 x 107 were achieved for PCs with the highest thickness, representing a competitive performance concerning typically reported values (104–107) for current noble metal-based PCs technologies and a new record concerning PCs fabricated by LIL (104–105). This research demonstrates the high competitivity of these simple Au nanodisks-based 2D PCs, fabricated using an efficient large-scale and low-cost lithography technique, for fast, high spectral resolution and highly reproducible SERS-based molecular sensing.
•Large-scale Au nanodisks-based Photonic Crystals (PCs) were fabricated.•Laser Interference Lithography (LIL) was used as nanopatterning technique.•High quality and large-scale homogeneity (>2 cm2) PCs were achieved.•PCs show outstanding performance for fast and high spectral resolution SERS.•A SERS enhancement factor of 2 x 107 was achieved for 2.6 ng/cm2 of MB.
In this study we used photosynthetic pigments extracted from spinach and purple cabbage for their potential application in dye sensitized solar cells (DSSC). Pigments were extracted by dissolving ...small amounts of each one of these plant products in methanol and distilled water. The extraction was also done at two different temperatures (70° C and 80° C respectively). This was to assess for the solvent that promotes better extraction of the pigments. A parallel study was also carried out using a mixture of both these dyes in 1:1 ratio. Good absorption, about 60% to 80% was obtained for spinach pigments diluted in methanol in the visible range between 400-480nm, and between 9% to 15% for purple cabbage pigments in the wavelength range between 480-630 nm when extracted using distilled water at 80°C. In contrast, the diluted mixture in methanol shows good absorption of 20% and 32% for wavelengths in the range 400-480nm. Solar cells sensitized using these natural dyes were studied for their photovoltaic properties by measuring current-voltage behavior. Efficiencies ranging from 0.011% to 0.0719% were observed. Mixture of spinach & purple cabbage pigments extracted using methanol was found to have the highest efficiency of 0.0719%.
Las acciones de Repsol llegaron a subir un 3,8% después de la publicación de su nuevo plan estratégico. Sin embargo, un informe negativo de Goldman Sachs dio la vuelta a su cotización.
Cellnex y Merlin están listas para completar la metamorfosis del Ibex, aunque tendrán que esperar. Hoy no se han aprobado cambios en la reunión del Comité Técnico Asesor del selectivo.
Ha detectado casos de Sicav con consejeros que realizan funciones de asesoramiento sin que así conste en los correspondientes folletos de las carteras.
Abengoa se propone realizar las primeras ventas de activos en septiembre. Inversión Corporativa, controlada por los Benjumea, prestó 95,3 millones de acciones de Abengoa entre mayo y junio.
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