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Abstract : Design Approaches to Improve Organic Solar Cells
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Abstract: Organic solar cells (OSC)s are valuable economical and environmental friendly devices capable to generate electricity from sunlight. This is because of their simple fabrication process and minimal material usage in comparison to the inorganic solar cells. OSCs have not been widely commercialized yet because of their relatively low power conversion efficiency and stability problem. It is expected that these obstacles will be surmounted in a foreseeable future upon rigorous research studies performed in the field. This paper is devoted to reviewing the design related strategies that can be taken to enhance OSC performance. These strategies can be accomplished through modulating the architecture of the devices and by considering the alignment of the molecular energy levels between their active layer components. Keywords: Organic solar cell, Nanostructure material, OSC performance, OSC efficiency, OSC improvement.Download Full Article |
Abstract : Solvent Isotope Effect on Transfer Hydrogenation of H2O with Glycerine under Alkaline Hydrothermal Conditions
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Abstract: Solvent isotope effect was investigated with 1H-, 2H-NMR, LC-MS and Gas-MS analyses on transfer hydrogenation of H2O with glycerine under alkaline hydrothermal conditions. The results from solvent isotope studies showed that (1) the H on the β-C of lactate was almost exchanged by D2O, which suggests that the hydroxyl (-OH) group on the 2-C of glycerine was first transformed into a carbonyl (C=O) group and then was converted back into a -OH group to form lactate; (2) The presence of large amountsof D was found in the produced hydrogen gas, which shows that the water molecules acted as a reactant; and (3) D% in the produced hydrogen gas was far more than 50%, which straightforwardly shows that acetol was formed in the first place as the most probable intermediate by undergoing a dehydration reaction rather than a dehydrogenation reaction. Keywords: Solvent isotope effect, transfer hydrogenation, glycerine, hydrothermal reaction.Download Full Article |
Abstract : Wind Turbine and Photovoltaic Hybrid Generations under Extreme Operating Gust
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Abstract: A micro-grid consisting of a 300kW wind turbine and a 40kW photovoltaic array is investigated under extreme operating gust (EOG) wind scenarios. The micro-grid is connected to the 380-V utility through a utility-side converter using natural-frame control, which provides a constant voltage of the DC link between the micro-grid and utility. The impact of the extreme gust wind variations on the micro-grid performance is studied for variable speed wind energy system equipped with a squirrel-cage induction generator. The Hurghada city, Red Sea, Egypt is taken as a case study for the wind speed profile. A detailed model of extreme gust-wind speed variation is implemented and simulated using PSIM commercial software package, based on climate characteristics of Hurghada city. The indirect rotor field oriented control (FOC) method is implemented to the generator-side converter to keep the system stable under the extreme gust wind conditions and to control the squirrel-cage induction generator (SCIG) speed for maximum power-point tracker (MPPT) regime. Power quality of the utility-side converter in terms of operation at different power factors, voltage value and THD are verified. Keywords: Gust winds, induction generator, micro-grid, photovoltaic, wind turbine.Download Full Article |
Abstract : Zinc Oxide Nanostructures for Efficient Energy Conversion in Organic Solar Cell
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Abstract: We present a new approach of solution-processed using zinc oxide (ZnO) nanostructures as extraction layer material for organic solar cells. It is low chemical reaction compatibility with all types of organic blends and its good adhesion to both surfaces of ITO/glass substrate and the active layer (blends). Parameters such as the thickness and the morphology of the films were investigated to prove that these factors greatly affect the efficiency of organic solar cells. In this work, ZnO layer with thickness of approximately 53 nm was used as an interlayer to prevent pin-holes between the electrode and the polymer layer. The polymer layer was coated on the ZnO layer with the thickness of about 150 nm. The thick polymer layer will form a non-uniform surface because of the solvent, 1-2dichlorobenzene will etch away some region of the polymer layer and forming pin-holes. ZnO nanostructures layer was used to prevent pin-holes between the polymer layer and electrode. From the surface morphology of ZnO layer, it shows a uniform surface with particle grain size obtained between 50 -100 nm. The presence of the interlayer has a positive effect on the electrical characteristics of the solar cells. It was found that an organic solar cell with thickness less than 150 nm shows the optimum performance with efficiency of 0.0067% and Fill Factor (FF) of about 19.73. Keywords: Nanostructures, extraction layer, pin-holes, poly (3-hexylthiophene) (P3HT), [6,6]-phenyl C61-butyric acid methyl ester (PCBM).Download Full Article |
