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<a href="http://web.mit.edu/mitei/news/seminars/" border="0" > <img src="http://web.mit.edu/miteicomm/announcements/mitei-series-banner.jpg" alt="MITEI: MIT Energy Initiative" style="padding-top:5px;"/></a>
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<h1>Organic and Dye Sensitized Solar Cells</h1>
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<h1>Michael McGehee</h1>
<h3>Associate Professor of Materials Science and Engineering and Director of the Center for Advanced Molecular Photovoltaics, Stanford University</h3>
<h3>Tuesday, March 8</h3>
<h3>4:15 PM</h3>
<h3><a href="http://whereis.mit.edu/?go=66"> Room 66-110 </a></h3></td>
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<p><strong>Abstract</strong></p>
<p>Organic solar cells and dye sensitized solar cells are very promising because they can be deposited rapidly in roll-to-roll coating machines without expensive vacuum chambers or high temperature processing. Since they can be lightweight and flexible, it may soon be possible to roll them onto rooftops at a cost several times lower than is now possible with silicon or cadmium telluride solar cells. Since organic semiconductors do not contain any rare or toxic elements, such as indium, cadmium or tellurium, organic solar cells could be used to provide the world with a significant fraction of its electricity.</p>
<p>My research group has used synchrotron x-ray diffraction and other characterization techniques to reveal in detail how semiconducting polymer chains and fullerene molecules pack in solar cells and shown how this packing influences the electronic processes that determine how well solar cells work. We have also measured the lifetime of polymer solar cells and found it to be as high as 7 years.</p>
<p>We have also pioneered the use of long range Forster energy transfer to improve light absorption in solar cells. We believe that the incorporation of energy relay dyes into dye sensitized solar cells (DSCs) is going to make it possible to raise their efficiency from 11 to 15% in the next few years by extending the region of the spectrum that the cells can absorb farther out into the infrared, where almost half of the sun's energy is located.</p>
<p>One of the great challenges to making highly efficient solar cells with solution deposited films that have high defect densities is keeping the films thin so the charge carriers can be collected before recombination occurs while at the same time absorbing all of the light. We have recently demonstrated that absorption and power conversion efficiency can be increased by as much as 20% simply by nanoimprinting an array of domes into the active layer before depositing a silver electrode so that incoming light can be coupled into plasmonic modes that travel in the plane of the solar cell.</p>
<p><strong>About the speaker</strong></p>
<p>Michael D. McGehee is an Associate Professor in the Materials Science and Engineering Department and Director of the Center for Advanced Molecular Photovoltaics at Stanford University. His research interests are patterning materials at the nanometer length scale, semiconducting polymers, large area electronics and renewable energy. He has taught courses on nanotechnology, organic semiconductors, polymer science and solar cells. He received his undergraduate degree in physics from Princeton University and his PhD degree in Materials Science from the University of California at Santa Barbara, where he did research on polymer lasers in the lab of Nobel Laureate Alan Heeger. He did postdoctoral research with Galen Stucky and Brad Chmelka at the University of California at Santa Barbara on the self-assembly of organic-inorganic mesostructures. He has won the 2007 Materials Research Society Outstanding Young Investigator Award and the Mohr Davidow Innovators Award.</p>
<p><strong>The Seminar Series is made possible with the generous support of IHS-CERA</strong></p>
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