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Solar Energy Conversion (solar + energy_conversion)
Selected AbstractsStudies of the micellar effect on photogalvanics: Solar energy conversion and storage,EDTA,safranine O,DSS systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2010Prerna Gangotri Abstract The studies of the micellar effect on photogalvanics was done for solar energy conversion and storage in photogalvanic cell containing dioctyl sodium sulphosuccinate as anionic micellar species, EDTA as reductant and safranine O as photosensitizer. The photopotential and photocurrent generated were 800.0,mV and 65.0,µA respectively. The observed conversion efficiency was 0.2532 per cent, the fill factor was 0.38 and the maximum power of the cell was 52.0,µW whereas the power at power point of the photogalvanic cell was 26.34,µW. The rate of initial generation of current was 37.5,µA,min,1. The photogalvanic cell can be used for 80.0,minutes in the dark. The effects of different parameters on the electrical output of the photogalvanic cell were observed and a mechanism has also been proposed for the generation of photocurrent in the photogalvanic cell. Copyright © 2009 John Wiley & Sons, Ltd. [source] Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition techniqueCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006J. Joseph Abstract Stannous oxide (SnO2) thin film is one of the most widely used n-type transparent semi-conductor films in electronics, electro-optics and solar energy conversion. By achieving controlled non-stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo-electronic, optical and electrical properties of the doped and undoped films were studied. The results of X-ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U-V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n-type to p-type and p-conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enhancement of Thermoelectric Figure-of-Merit by a Bulk Nanostructuring ApproachADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Yucheng Lan Abstract Recently a significant figure-of-merit (ZT) improvement in the most-studied existing thermoelectric materials has been achieved by creating nanograins and nanostructures in the grains using the combination of high-energy ball milling and a direct-current-induced hot-press process. Thermoelectric transport measurements, coupled with microstructure studies and theoretical modeling, show that the ZT improvement is the result of low lattice thermal conductivity due to the increased phonon scattering by grain boundaries and structural defects. In this article, the synthesis process and the relationship between the microstructures and the thermoelectric properties of the nanostructured thermoelectric bulk materials with an enhanced ZT value are reviewed. It is expected that the nanostructured materials described here will be useful for a variety of applications such as waste heat recovery, solar energy conversion, and environmentally friendly refrigeration. [source] Studies of the micellar effect on photogalvanics: Solar energy conversion and storage,EDTA,safranine O,DSS systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2010Prerna Gangotri Abstract The studies of the micellar effect on photogalvanics was done for solar energy conversion and storage in photogalvanic cell containing dioctyl sodium sulphosuccinate as anionic micellar species, EDTA as reductant and safranine O as photosensitizer. The photopotential and photocurrent generated were 800.0,mV and 65.0,µA respectively. The observed conversion efficiency was 0.2532 per cent, the fill factor was 0.38 and the maximum power of the cell was 52.0,µW whereas the power at power point of the photogalvanic cell was 26.34,µW. The rate of initial generation of current was 37.5,µA,min,1. The photogalvanic cell can be used for 80.0,minutes in the dark. The effects of different parameters on the electrical output of the photogalvanic cell were observed and a mechanism has also been proposed for the generation of photocurrent in the photogalvanic cell. Copyright © 2009 John Wiley & Sons, Ltd. [source] New routes to sustainable photovoltaics: evaluation of Cu2ZnSnS4 as an alternative absorber materialPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2008Jonathan J. Scragg Abstract Thin film heterojunction solar cells based on chalcopyrites such as Cu(In,Ga)Se2 have achieved impressive efficiencies. However concern about the long term sustainability of photovoltaics based on scarce or expensive raw materials has prompted the search for alternative absorber materials. In this work, films of the p-type absorber Cu2ZnSnS4 (CZTS) were prepared by electroplating metallic precursors sequentially onto a molybdenum-coated glass substrate followed by an nealing in a sulfur atmosphere. The polycrystalline CZTS films were characterized by photoelectrochemical methods, which showed films were p-type with doping densities of the order of 1016 cm,3 and a band gap of 1.49 eV, close to the optimum value for terrestrial solar energy conversion. Preliminary results obtained for solar cells fabricated with this material are promising. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Limiting efficiency for current-constrained two-terminal tandem cell stacksPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2002Andrew S. Brown Tandem stacks of solar cells have clearly shown their ability to increase the efficiency of solar energy conversion. In the past, the challenge in making these devices often has been in the materials science area, working around the constraints imposed by different materials to meet requirements imposed by lattice constant and bandgap. However, developments in the field of low-dimensional structures; particularly superlattices, may allow generic approaches to developing tandem stacks of large numbers of cells. The current flowing through such devices will have to be constrained so that it is the same through all the cells within the stack since separately contacting such large numbers of cells is impractical. The series-constrained two-terminal tandem solar cell is compared with the unconstrained tandem solar cell for stacks containing both small and large numbers of cells. As expected, we find that the detailed balance limiting efficiencies for the two-terminal cell are less than those for the unconstrained device involving the same number of cells, due to the constraint imposed by current matching. However the difference is always less than 1.5% relative under the design spectrum. However, the two-terminal case shows much greater variation in efficiency if the spectrum varies from that for which the design was optimised. A relationship is derived between the performance of a two-terminal stack of a finite number of cells and the performance of an unconstrained stack of an infinite number of cells. This shows that the performance of the two-terminal device approaches that of the unconstrained device as the number of cells in the stack approaches infinity. Copyright © 2002 John Wiley & Sons, Ltd. [source] Thinnest Two-Dimensional Nanomaterial,Graphene for Solar EnergyCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 7 2010Yun Hang Hu Prof. Abstract Graphene is a rapidly rising star in materials science. This two-dimensional material exhibits unique properties, such as low resistance, excellent optical transmittance, and high mechanical and chemical stabilities. These exceptional advantages possess great promise for its potential applications in photovoltaic devices. In this Review, we present the status of graphene research for solar energy with emphasis on solar cells. Firstly, the preparation and properties of graphene are described. Secondly, applications of graphene as transparent conductive electrodes and counter electrodes are presented. Thirdly, graphene-based electron- (or hole) accepting materials for solar energy conversion are evaluated. Fourthly, the promoting effect of graphene on photovoltaic devices and the photocatalytic property of graphene,semiconductor composites are discussed. Finally, the challenges to increase the power conversion efficiency of graphene-based solar cells are explored. [source] | |||||||||||||