Abstracts Invited Speakers
| Challenges in Nanomaterials for Sun Light to Electrical Energy Conversion, Artificial Photosynthesis and Energy Storage Joan R. Morante, Catalonia Institute for Energy Research, Spain Abstract: In the last years, single crystal nanomaterials have emerged as building blocks of innovative devices and circuit architectures, due to their new and astonishing properties derived from their reduced size and well-controlled chemical and physical properties. To date, a great effort has been made to achieve control in the synthesis as well as in the electrical and optical properties of these nanomaterials. Nevertheless, the development of real proof-of-concepts nanodevices remains in a very promising preliminary stage. The use of these nanomaterials reveals and emphasizes both phonon- and photon-related properties, owing to the fact that they are monocrystals at the nanoscale with a strong coupling between surface and bulk transport phenomena together with geometric issues due to the limited sized of the nanostructure. These one-dimensional nanostructures show flashing and exciting features concerning photon absorption, electron-hole separation; chemical interactions at the surface and surface-state population effects on bulk characteristics and so on. However, they still have a large amount of unsolved questions related to the fundamental knowledge of the mechanisms which take place as active elements for solar energy conversion to electrical energy by means of photovoltaic effect, for thermoelectric effects; or for direct conversion of sun photons to chemical energy in controlled photocatalytic processes. In this contribution, the use of low dimensional nanostructured material with different geometries (i.e. axial and coaxial nanowires or core/shell nano particles) to obtain competitive devices with real integration chances is reviewed in detail. These nanostructures, which are among the most promising nanomaterials, have already demonstrated their suitability to build up electronic transistors, chemical and biochemical sensors and photodetectors with high sensitivity, stable and reproducible characteristics; and to design photovoltaic, thermoelectric and photocatalytic elements with outstanding performances. Challenges for achieving very high photovoltaic efficiency; thermo electrical figure of merit; photo catalytic or photo electrochemical – artificial photosynthesis- efficiencies for the above applications will be analyzed and discussed as key stones for the future nanoenergy technologies. Likewise, special attention will be paid to the use of some of these nanostructured materials as active elements in energy storage system which is one of the most outstanding problems in the tomorrow energy models. Device examples and an overview of the possible applications of the technology based on low dimensional structures will be presented. Future work guidelines to achieve more complex systems based on these nanomaterials, good enough to become commercial products will be also discussed.
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| Single and Multi-Crystalline Silicon for Photovoltaic (and Microelectronic) Applications Talid R. Sinno, University of Pennsylvania Abstract: The production of ultra-pure silicon crystals is a key step in the fabrication of both photovoltaic and microelectronic devices. Important issues in this process range from purification of the raw material (silica) to the crystallization of purified silicon into large, nearly perfect single crystals. This presentation first discusses the important steps in the large-scale industrial manufacture of ultra-pure silicon for the photovoltaic and microelectronic industries, which both require enormous quantities of the material. The latter part of the presentation focuses on microscopic issues, such as defect formation and impurity atom distribution, which reduce the efficiency of PV cells and the manufacturing yield of microelectronic devices. |
| Nanocrystals for Solar Cell Applications Marija Drndic, University of Pennsylvania Abstract: Nanocrystals are small particles a few nanometers in size. Their physical properties, such as light absorption and emission, can be controlled to a large extent by tuning their size, shape and composition. Efforts to explore nanocrystals unite the frontiers of physics, chemistry and engineering, and open up new applications. In this talk, I will discuss the efforts to integrate nanoparticles into efficient solar cells and outline some current challenges towards this goal. |
| Fuel Cells for Efficient Energy Conversion John M. Vohs, University of Pennsylvnia Abstract:Fuel cells have much potential as highly efficient energy conversion devices for use in distributed power systems, including those in the transportation sector. Their inherently high efficiency allows for better utilization of fossil fuels while decreasing the emission of greenhouse gasses, and coupled with renewable methods for hydrogen production they could allow for carbon neutral electrical power generation. In this talk I will initially give an overview of several of the most promising fuel cell technologies, including their operating principles and materials of construction, the applications that they are targeted for, and the technological barriers to their commercialization. I will then present an overview of our research into the development of microstructured anodes and cathodes for highly fuel flexible solid oxide fuel cells. |
| Liquid Crystals: Their contribution to the field of Photovoltaics Luz J. Martinez-Miranda, University of Maryland Abstract: Organic photovoltaic cells are studied because of their ease of fabrication and relatively low price. In 2003, the results of a heterojunction consisting of a liquid crystal and a polymer were published. Heterojunctions studied until then consisted principally of an electron donor polymer and an electron acceptor polymer. Liquid crystals exhibit molecular orientation in their ordered phases (the smectic and the nematic). Alignment of the liquid crystal such that the delocalized electrons are parallel to the substrate provides a path for electrons, and holes, to move between and to reach the electrodes. Nanoparticles incorporated in a liquid crystal tend to align in rows in the liquid crystal. Together they form a heterojunction whose properties can be varied according to the nanoparticle size and shape, and the type of liquid crystal used. Nanowires combined with liquid crystal have the same effect while providing more support to the structure. The enhanced ordering of the liquid crystals can contribute to the increase in the efficiency of solar cells made up of organic materials. |
| Alternatives to Petroleum-Sustainable Fuels and Chemicals for Biomass E. Kendall Pye, Lignol Innovations, Canada Abstract: Since the first oil well was drilled in 1853 life has changed dramatically in industrialized countries. Low cost crude oil has allowed automobiles, aircraft, goods transportation by trucks and diesel locomotives to replace horses and sailing ships. Home heating oil, construction materials like plywood and counter top laminates, everyday items such as nylon and polyester clothing, plastic film, driveway coatings and styrofoam containers, also depend on low cost oil. But crude oil is a finite and non-renewable resource and many predict that the "easy"- and therefore cheap - oil will soon be depleted. Will this mean a major change in our life styles? Not necessarily, because by using new technology, woody biomass such as corn stover and straw, together with plantation trees not now needed by a declining pulp and paper industry, can be sustainable sources of chemicals and transportation fuels that replace those currently made from oil. Biorefineries that process woody biomass into useful chemicals and fuels will replace oil refineries, but will be environmentally benign, will create a major new domestic industry and will reduce the need for oil imports from politically unstable countries. These trends will be discussed. |
