Sometimes high tech is positively old-fashioned. Consider the purple pokeberry: a favorite of kids wishing to stain their face and clothes–as well as Civil War soldiers, pressed for ink, writing letters home–it would now appear that the dye produced by the berries of this common weed holds the key to cheaper, more efficient solar panels.
Researchers at the Wake Forest University Center for Nanotechnology recently found that by coating their patented (and inexpensive) fiber-based solar cells with the red dye made from pokeberries, efficiency was increased . That’s because the dye acts as an absorber, helping the cell’s tiny fibers trap more sunlight and convert more power (nearly twice as much as conventional thin-film solar cells). Wake Forest’s fiber solar cells–currently being developed for the commercial market by their spin-off company, FiberCell, Inc.–are made from plastic fibers are stamped onto plastic sheets, with the same technology used to attach the tops of soft-drink cans. They’re then sprayed with an absorber–either a polymer or now, the less-expensive, homegrown option: purpe pokeberry dye.
The implications for light, flexible solar cells produced using a common manufacturing technology and sprayed with a cheap, widely available absorber are not lost on those developing them. According to David Carroll, Ph.D., the center’s director, they could easily be used in Africa, where residents could purchase the inexpensive fiber solar cells, then grow (and spray on) the absorber themselves. “They’re weeds,” Carroll said, in a statement, concerning purple pokeberries. “They grow on every continent but Antarctica.”
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