The solvent that Michael McGehee is holding in a test-tube-size bottle is an intense ruby red. His lab is testing a new semiconducting polymer that gives the liquid its color and is six times better in electronic performance than previous materials. “That’s why people are so excited by it,” says the assistant professor of materials science and engineering.
McGehee estimates that in three to five years, the semiconducting polymer, which looks like a wafer of thin red film in its solid state, will be used in flat-panel display televisions and in radio frequency identification tags, like those in cars that drive through automated toll booths. If the production price can be significantly reduced, from a couple of dollars to about a penny per tag, consumers may see them on purchases at big-box stores. “You wouldn’t need a checkout counter because people could just drive by with their carts,” McGehee says. “It would be faster and more convenient, and should cut down on shoplifting enormously. And it would give the store a very accurate inventory.”
McGehee was asked to test the performance of the new semiconducting polymer by Merck Chemicals in the United Kingdom, which developed it. His findings, which appeared in the April 2006 edition of Nature Materials, suggested that electronics made from polymers may provide inexpensive circuits for everyday products. But the polymer is not a replacement for the silicon in computer chips, which require much higher speeds. “It’s for applications where a large area is required, where flexibility is required and where low cost is required.”
McGehee’s main research project aims to produce solar cells that are 20 percent more efficient than today’s, and five to 10 times cheaper. Six years ago, he says, it was hard to find interested students for his lab. Today he’s turning them away. “A lot of students are concerned about global warming. Some will go into policy, some will learn about environmental issues, and others will say, ‘I’m an engineer and I want to make something to prevent global warming.’”
Students in McGehee’s lab are attempting to cut costs by printing solar cells on roll-to-roll coating machines like those used for photographic film. “We hope they would incorporate [solar cells] directly into roofing material, so people installing a roof would have solar cells built right into it.”
