7 research outputs found

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

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    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

    Electrochemistry for solar energy conversion systems : a selection of mexican contributions

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    Electrochemistry is a key technology to synthesize, study and scale-up materials and processes for applications in solar energy conversion systems. Mexico has had a tradition of excellence in electrochemistry research and methodology development, and this paper intends to honor some of the key contributors in the subjects of solar energy conversion to useful heat or electricity. We summarize the use of electrochemical techniques as a tool for the deposition and characterization, including the analysis of electrodeposition solutions and deposition mechanisms. In addition, we describe the use of electrodeposited and hybrid ZnO films for application in dye-sensitized solar cells, which are photoelectrochemical systems, and discuss the mechanisms that govern solar cell performance.Special Issue. Tribute to the electrochemical emeritus researchers of SNI</p

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

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    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

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    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

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

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    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
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