Solar gain

Renewable energy from the sun is getting a boost in solar cell research at South Carolina

The golden rays of the sun are getting a little help from nano-sized particles of gold in a Department of Energy-sponsored research project on solar cells.

Two South Carolina chemistry professors are developing the special nanoparticles in their labs that could improve the light-gathering and electricity-generating efficiency of hybrid organic/inorganic solar cells.

Cathy Murphy and Richard Adams are collaborating with Wake Forest University physicist Dave Carroll on a threeyear, $810,000 grant sponsored by the Department of Energy. The grant is one of 27 funded by DOE from a pool of more than 600 proposals; all are related to solar energy research.

“Solar cells still are not cost effective for large-scale use,” Adams said. “But if they were more efficient, large-scale applications would make more sense.

There is a lot of solar energy, but it is fairly dilute—that’s why we need to improve the efficiency of solar cells.”

Murphy is developing silver and gold nano particles—shaped like tiny rods— that improve the absorption of visible light and amplify its effects. “You can tune the wavelength of light absorbed by changing the size of the nanorods,” Murphy said. “A single layer of these silver or gold nanorods in the solar cell is all that’s needed to get the improvement.”

Adams is developing metal sulfide nanoparticles that aid in creating photocurrents from the gathered solar energy. Carroll, their Wake Forest University collaborator, will load the nanoparticles into solar cells, which will be tested at the National Renewable Energy Laboratory in Golden, Colo.

The team plans to have a working solar cell model before the grant expires. “I think we have a good chance of making some improvements to the existing technology for solar cells,” Adams said. “If we can help improve their efficiency, we’ll have made a worthwhile contribution.”

To further its research on photovoltaic energy, South Carolina is recruiting a cluster of faculty in chemistry, mechanical engineering, and electrical engineering who will concentrate their research in this area. The cluster hire, which will be funded through the University’s Faculty Excellence Initiative, is expected to bring one or two faculty members to campus by this fall with more to follow.

“We anticipate exploring broad uses of solar energy and looking at combined photovoltaic and thermal systems,” said Roger Dougal, an electrical engineering professor who is chairing the search for the cluster recruitment. “The heat from a solar panel is low grade and usually thrown away, but it could be used in residential or commercial systems for hot water and space heating or with thermoelectrics to produce additional electric power.”

To get students interested early on about photovoltaic research, the College of Engineering and Computing offered a course on photovoltaics during the winter interim session at the Governor’s School for Science and Mathematics, a special high school for gifted students in Hartsville, S.C.