Influence of Redox Couple on the Performance of ZnO Dye Solar Cells and Minimodules with Benzothiadiazole-Based Photosensitizers

ZnO-based dye-sensitized solar cells exhibit lower efficiencies than TiO2-based systems despite advantageous charge transport dynamics and versatility in terms of synthesis methods, which can be primarily ascribed to compatibility issues of ZnO with the dyes and the redox couples originally optimized for TiO2. We evaluate the performance of solar cells based on ZnO nanomaterial prepared by microwave-assisted solvothermal syn- thesis, using three fully organic benzothiadiazole-based dyes YKP- 88, YKP-137, and MG-207, and alternative electrolyte solutions with the I−/I3−, Co(bpy)32+/3+, and Cu(dmp)21+/2+ redox couples. The best cell performance is achieved for the dye−redox couple combination YKP-88 and Co(bpy)32+/3+, reaching an average −− efficiency of 4.7% and 5.0% for the best cell, compared to 3.7% and 3.9% for the I /I3 couple with the same dye. Electrical impedance spectroscopy highlights the influence of dye and redox couple chemistry on the balance of recombination and regeneration kinetics. Combined with the effects of the interaction of the redox couple with the ZnO surface, these aspects are shown to determine the solar cell performance. Minimodules based on the best systems in both parallel and series configurations reach 1.5% efficiency for an area of 23.8 cm2.Área de Química Físic

Scaffold proteins LACK and TRACK as potential drug targets in kinetoplastid parasites: Development of inhibitors

Parasitic diseases cause similar to 500,000 deaths annually and remain a major challenge for therapeutic development. Using a rational design based approach, we developed peptide inhibitors with anti-parasitic activity that were derived from the sequences of parasite scaffold proteins LACK (Leishmania's receptor for activated C-kinase) and TRACK (Trypanosoma receptor for activated C-kinase). We hypothesized that sequences in LACK and TRACK that are conserved in the parasites, but not in the mammalian ortholog, RACK (Receptor for activated C-kinase), may be interaction sites for signaling proteins that are critical for the parasites' viability. One of these peptides exhibited leishmanicidal and trypanocidal activity in culture. Moreover, in infected mice, this peptide was also effective in reducing parasitemia and increasing survival without toxic effects. The identified peptide is a promising new anti-parasitic drug lead, as its unique features may limit toxicity and drug-resistance, thus overcoming central limitations of most anti-parasitic drugs. (C) 2016 The Authors. Published by Elsevier Ltd on behalf of Australian Society for Parasitology.National Institutes of HealthStanford Univ, Sch Med, Dept Chem & Syst Biol, Stanford, CA 94305 USAUniv Sao Paulo, Inst Quim, Dept Bioquim, BR-05508 Sao Paulo, SP, BrazilMcGill Univ, Res Inst, Natl Reference Ctr Parasitol, Montreal, PQ, CanadaUniv Autonoma Yucatan, Ctr Invest Reg Dr Hideyo Noguchi, Parasitol Lab, Merida, Yucatan, MexicoStanford Univ, Biomat & Adv Drug Delivery Lab, Stanford, CA 94305 USAUniv Estadual Campinas, Inst Chem, Campinas, SP, BrazilUniv Fed Sao Paulo, Dept Ciencias Biol, Campus Diadema, Sao Paulo, BrazilMcGill Univ, Inst Parasitol, Quebec City, PQ, CanadaMcGill Univ, Ctr Host Parasite Interact, Quebec City, PQ, CanadaUniv Fed Sao Paulo, Dept Ciencias Biol, Campus Diadema, Sao Paulo, BrazilNIH: TW008781-01C-IDEANIH: AI078505Web of Scienc

Electrodepósito de níquel negro sobre aletas de cobre para aplicaciones en colectores solares planos

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: En este trabajo se reporta el desempeño de colectores solares construidos con aletas de cobre recubiertas con níquel/níquel negro con y sin SiO2. Los recubrimientos de níquel y níquel negro fueron obtenidos mediante electrodepósito y la capa de SiO2 por sol-gel y roció pirolítico, los resultados se comparan con un colector construido con un recubrimiento selectivo comercial TiNOX. Los resultados muestran que el níquel negro con SiO2 tiene una curva de desempeño cercana al colector construidos con el recubrimiento comercial. El recubrimiento de níquel negro con SiO2 fue obtenido por técnicas de bajo costo lo cual pudiera ser atractivo para las empresas dedicadas a la construcción de colectores solares.ABSTRACT: This work reports the performance of solar collectors built with nickel / black nickel coated copper fins with and without SiO2. The nickel and black nickel coatings were obtained by electrodeposition, the SiO2 layer by sol-gel and spray pyrolysis methods, the results are compared with a collector built with a commercial selective coating TiNOX. The results show that black nickel with SiO2 have a near performance curve than the collector built with the commercial coating. The black nickel coating with SiO2 was obtained by low cost techniques which could be attractive for companies dedicated to the construction of solar collectors.info:eu-repo/semantics/publishedVersio

Mechanisms of electron transport and recombination in ZnO nanostructures for dye-sensitized solar cells

ZnO is an attractive material for applications in dye-sensitized solar cells and related devices. This material has excellent electron-transport properties in the bulk but its electron diffusion coefficient is much smaller in mesoporous films. In this work the electron-transport properties of two different kinds of dye-sensitized ZnO nanostructures are investigated by small-perturbation electrochemical techniques. For nanoparticulate ZnO photoanodes prepared via a wet-chemistry technique, the diffusion coefficient is found to reproduce the typical behavior predicted by the multiple-trapping and the hopping models, with an exponential increase with respect to the applied bias. In contrast, in ZnO nanostructured thin films of controlled texture and crystallinity prepared via a plasma chemical vapor deposition method, the diffusion coefficient is found to be independent of the electrochemical bias. This observation suggests a different transport mechanism not controlled by trapping and electron accumulation. In spite of the quite different transport features, the recombination kinetics, the electron-collection efficiency and the photoconversion efficiency are very similar for both kinds of photoanodes, an observation that indicates that surface properties rather than electron transport is the main efficiency-determining factor in solar cells based on ZnO nanostructured photoanodes. Two very different behaviors of the electron-transport properties are found in nanostructured ZnO-based photoanodes. Texturized samples show a voltage-independent transport time, whereas films produced from nanocrystalline powders exhibit a voltage-dependent signal, consistent with trap-limited electron diffusion.Peer Reviewe

ZnO/ZnO Core–Shell Nanowire Array Electrodes: Blocking of Recombination and Impressive Enhancement of Photovoltage in Dye-Sensitized Solar Cells

A multistep wet-chemistry route was developed, by combining electrodeposition, colloidal synthesis and spin coating, to obtain arrays of ZnO nanowires (NWs) coated by a ZnO nanocrystalline layer (i.e., ZnO/ZnO core–shell NWs). They were integrated as anodes in dye-sensitized solar cells. With the use of an iodide-based electrolyte, photovoltages as impressive as 870 mV were obtained with an enhancement of more than 250 mV with respect to devices based on bare NWs. A comprehensive device characterization study by means of impedance spectroscopy (EIS) and intensity-modulated photovoltage spectroscopy (IMVS) reveals a significant blockage of recombination upon NW shell deposition. To study the generality of this multistep method, electrodes of core–shell nanostructures based on commercial ZnO nanoparticles were also prepared. A decrease of recombination rate is also detected, although it is much more moderate than the observed for nanowire-based electrodes. The present ZnO synthetic approach allows obtaining nanowire-based dye-sensitized solar cells which exhibit longer electron lifetimes than nanocrystalline analogues. This finding implies a significant improvement of photovoltage with respect to the state of the art ZnO-based dye-sensitized solar cells

Influence of Redox Couple on the Performance of ZnO Dye Solar Cells and Minimodules with Benzothiadiazole-Based Photosensitizers

International audienceZnO-based dye-sensitized solar cells exhibit lower efficiencies than TiO 2-based systems despite advantageous charge transport dynamics and versatility in terms of synthesis methods, which can be primarily ascribed to compatibility issues of ZnO with the dyes and the redox couples originally optimized for TiO 2. We evaluate the performance of solar cells based on ZnO nanomaterial prepared by microwave-assisted solvothermal synthesis, using three fully organic benzothiadiazole-based dyes YKP-88, YKP-137, and MG-207, and alternative electrolyte solutions with the I-/I 3-, Co(bpy) 3 2+/3+ , and Cu(dmp) 2 1+/2+ redox couples. The best cell performance is achieved for the dye-redox couple combination YKP-88 and Co(bpy) 3 2+/3+ , reaching an average efficiency of 4.7% and 5.0% for the best cell, compared to 3.7% and 3.9% for the I-/I 3-couple with the same dye. Electrical impedance spectroscopy highlights the influence of dye and redox couple chemistry on the balance of recombination and regeneration kinetics. Combined with the effects of the interaction of the redox couple with the ZnO surface, these aspects are shown to determine the solar cell performance. Minimodules based on the best systems in both parallel and series configurations reach 1.5% efficiency for an area of 23.8 cm 2

Brookite-Based Dye-Sensitized Solar Cells: Influence of Morphology and Surface Chemistry on Cell Performance

The transport and recombination properties of dye-sensitized solar cells based on phase-pure anatase and brookite nanomaterials are compared as a function of the surface chemistry and morphology. Phase-pure brookite has been synthesized from amorphous TiO₂ using two different solutions at low and high pH, resulting in different size and morphology of brookite nanoparticles. The smaller short-circuit current density (<i>J</i>_SC = 6.6 mA cm^–2) for acidic brookite compared to anatase (9.8 mA cm^–2) was related to the light harvesting efficiency because of the lower amount of dye adsorbed. However, a larger open-circuit voltage for acidic brookite indicates the promise of the material. The basic brookite-based solar cells gave a very low <i>J</i>_SC (0.10 mA cm^–2), which increased dramatically by a factor of about 30 after an acid treatment of the films, illustrating the effect of surface chemistry. A combination of experiments shows that the improvement is related to an increase in injection efficiency. Electrochemical impedance and intensity-modulated photocurrent and photovoltage spectroscopies show that electron transport is faster in the acid-treated basic brookite nanomaterial, related to the larger feature sizes. However, the recombination kinetics is also significantly faster, with as net result a smaller diffusion length and hence smaller collection efficiency

Comparative Transcriptomes of the Body Wall of Wild and Farmed Sea Cucumber Isostichopus badionotus

Overfishing of sea cucumber Isostichopus badionotus from Yucatan has led to a major population decline. They are being captured as an alternative to traditional species despite a paucity of information about their health-promoting properties. The transcriptome of the body wall of wild and farmed I. badionotus has now been studied for the first time by an RNA-Seq approach. The functional profile of wild I. badionotus was comparable with data in the literature for other regularly captured species. In contrast, the metabolism of first generation farmed I. badionotus was impaired. This had multiple possible causes including a sub-optimal growth environment and impaired nutrient utilization. Several key metabolic pathways that are important in effective handling and accretion of nutrients and energy, or clearance of harmful cellular metabolites, were disrupted or dysregulated. For instance, collagen mRNAs were greatly reduced and deposition of collagen proteins impaired. Wild I. badionotus is, therefore, a suitable alternative to other widely used species but, at present, the potential of farmed I. badionotus is unclear. The environmental or nutritional factors responsible for their impaired function in culture remain unknown, but the present data gives useful pointers to the underlying problems associated with their aquaculture