11-06-02
BEHREND RESEARCHER DEVELOPS LESS COSTLY
METHOD TO CAPTURE SOLAR ENERGY
Dr. Bruce Wittmershaus and his undergraduate students in physics have teamed with Molecular Probes, Incorporated, of Eugene, Oregon, to develop new, less expensive ways to capture solar energy.
The project, supported by a $151,500 grant from the National Science Foundation, uses dyes manufactured by Molecular Probes to develop improved luminescent solar concentrator panels. These plastic panels absorb sunlight and concentrate light onto small areas of semiconductor solar cells that convert the light to electricity. By decreasing the amount of expensive semiconductor material needed, the plastic panels reduce costs.
Molecular Probes, Inc. is the leading manufacturer of fluorescent probes used extensively for visual labeling of cells in medicine and biology. It manufactures TransFluoSpheres, multiple-dye polystyrene spheres only 40 nanometers in diameter that are being used as part of project. The company is participating in Wittmershaus' research to learn more about the optical properties of its dyes with the aim of improving its current products and developing new ones.
"We enjoy those bright, fluorescent, neon-colored materials that enliven our homes and offices," said Wittmershaus, an associate professor of physics at Penn State Erie, The Behrend College. "These materials are constantly absorbing and re-emitting light. That emitted light can be captured and changed into electricity for our homes, businesses, and industry. This is not necessarily more efficient than semiconductor solar cells, but it can be cheaper."
Two major concepts underlie Wittmershaus's research. The first is total internal reflection. Fiber optics use internal reflection to trap light within the core of the fiber, transmitting the light over large distances with minimal losses. In a similar way, about seventy percent of the fluorescence from the dye in the panels is trapped inside and brought to the edges of the panel where it is efficiently absorbed by semiconductor solar cells and converted into electricity.
The second concept is that to absorb as much sunlight as possible, more than one dye is put into the panel. "As a result of total internal reflection, a translucent, flat surface colored by a single fluorescent dye will trap energy," said Wittmershaus. "Unique to our project is our use of multiple dyes, so that the most possible sunlight is absorbed for conversion to electrical energy. Eventually, we hope to make a plate which appears translucent black with its fluorescence too far into the red for your eyes to see."
Three papers and many conference presentations have resulted from the project, all including undergraduate student researchers. Much of the National Science Foundation funding supports student involvement in the project. To date, sixteen students have worked with Wittmershaus under the grant.
"Research is similar to the work environment and very different from the classroom," explains Wittmershaus. "The path taken is frustrating and sometimes full of obstacles and dead-ends. Its rewards highlight the power of good knowledge and deductive reasoning. This kind of student training is one of the best products of undergraduate research."
Contact:
Loretta Brandon
814-898-6063
e-mail: lzb6@psu.edu