References Toward cost-effective solar energy use Science, v 315, n 5813, 9 Feb. 2007, p Nanostructures for photovoltaics Materials Science and Engineering R: Reports, v 62, n 6, Nov 10, 2008, p Nanoscience and nanotechnology for advanced energy systems Current Opinion in Solid State and Materials Science, v 10, n 3-4, June/August, 2006, p Selected nanotechnologies for renewable energy applications International Journal of Energy Research, v 31, n 6-7, May, 2007, p

Renewable energy systems - Solar  Photovoltaics (PV): convert sun’s energy directly to electricity  Solar hydrogen: use sun’s energy to create H 2 by splitting water  H 2 storage: storing H 2 in solid-state forms  Hydrogen fuel cell: using H 2 to create electricity  Solar thermal: capturing and storing heat from sun  Photovoltaics (PV): convert sun’s energy directly to electricity  Solar hydrogen: use sun’s energy to create H 2 by splitting water  H 2 storage: storing H 2 in solid-state forms  Hydrogen fuel cell: using H 2 to create electricity  Solar thermal: capturing and storing heat from sun Solar furnace in France Solar thermal power plant in California Mojave desert. Nine plants with a total capacity of 350 MW providing enough electricity to meet the residential needs of a city with 250,000

Solar Cell Efficiency Efficiency limits for single-junction and tandem solar cells Solar Energy Materials and Solar Cells Volume 90, Issues 18-19, 23 November 2006, Pages th International Photovoltaic Science and Engineering Conference Carrier mobility, structural order, and solar cell efficiency of organic heterojunction devices Street, R.A. (Palo Alto Research Center) Source: Applied Physics Letters, v 93, n 13,, 2008, p Recent publications Designing randomness -the impact of textured surfaces on the efficiency of thin-film solar cells Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series, 2008 Conference on and Quantum Electronics and Laser Science Conference Lasers and Electro-Optics, QELS, 2008, p Enhanced efficiency of dye-sensitized solar cell using double-layered conducting glass Thin Solid Films, v 516, n 21, 1 Sept. 2008, p Ultra-high efficiency solar cells: The path for mass penetration of solar electricity Electronics Letters, v 44, n 16,, 2008

Textured silicon for reducing reflections

Tandem solar cell  Tandem solar cells contain two or more cells that enable light absorption over a broader range of wavelengths Triple-junction solar cell Novel materials for high-efficiency III-V multi-junction solar cells Solar Energy, v 82, n 2, Feb. 2008, p Thin film nanocrystalline silicon and nanostructured interfaces for multibandgap triple junction solar cells Surface and Interface Analysis, v 40, n 6-7, June/July, 2008, p Organic tandem and multi-junction solar cells Advanced Functional Materials, v 18, n 2, Jan 24, 2008, p

Dye-sensitized solar cells (DSSCs)

Nanostructures in DSSCs  Increase surface area of semiconductor to increase light absorption  Optimization of dye/semiconductor interface relies on nanoscale characterization and fabrication methods  Increase surface area of semiconductor to increase light absorption  Optimization of dye/semiconductor interface relies on nanoscale characterization and fabrication methods DSSC with ZnO nanowires TiO 2 nanotubes

Solar Energy  Improvements in efficiency  Significant reduction in manufacturing costs  Improvements in efficiency  Significant reduction in manufacturing costs All done in cost-effective manner  More energy from sunlight strikes Earth in 1 hour than all energy consumed by humans in an entire year Requirements for solar to be a primary source of energy  Captured  Converted  Stored  More energy from sunlight strikes Earth in 1 hour than all energy consumed by humans in an entire year Requirements for solar to be a primary source of energy  Captured  Converted  Stored To be cost competitive with fossil fuels, solar electricity must see Efficiencies of shipped PV modules: % at ~ $300/m 2