[E&E seminars] Tomorrow - Organic and Dye Sensitized Solar Cells - Michael McGehee

[MIT Energy Initiative]

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Organic and Dye Sensitized Solar Cells



Michael McGehee

Associate Professor of Materials Science and Engineering and Director
of the Center for Advanced Molecular Photovoltaics, Stanford University

Tuesday, March 8

4:15 PM

Room 66-110



 Abstract



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.



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.



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.



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.



About the speaker



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.



The Seminar Series is made possible with the generous support of
IHS-CERA





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