This is an excerpt from EERE Network News, a weekly electronic newsletter.

January 19, 2005

Paint-On Solar Cell Captures Infrared Radiation

New research at the University of Toronto (U of T) promises to yield new ways to capture the sun's infrared radiation, a part of the solar spectrum that's not captured by today's low-cost flexible thin-film solar cells. Using particles of semiconductor only 6 nanometers in size, the U of T team created a suspension of the particles in a solvent, much like paint, and then applied it to a surface to dry. The particles are so small that quantum effects determine the wavelength of light that they absorb, causing them to absorb infrared radiation, the invisible heat radiation given off by warm objects. The key to success was combining these particles—sometimes called "quantum dots"—with a solvent that would cause them to evenly disperse across the surface of a material. According to one reviewer of the work, the finding has the potential of eventually allowing flexible solar devices to boost their efficiency significantly, capturing 30 percent of the sun's energy. Today's flexible solar cells consist of a thin film of semiconductor material deposited on a flexible plastic substrate. See the U of T press release.

Researchers at Georgia Institute of Technology are working to boost the efficiency of a new type of flexible solar cell, the organic solar cell, in which the inexpensive, flexible material that forms the cell is also able to capture the sun's energy and convert it into electricity. The Georgia Tech researchers built their solar cells by combining pentacene—a 22-carbon molecule in which the carbon atoms form five rings linked together in a chain—with C-60, a large soccer-ball-shaped carbon molecule also called Buckminsterfullerine, or "buckyballs." The resulting organic solar cells were able to convert 3.4 percent of the sun's energy into electricity. See the Georgia Tech press release.