Phil Denby almost talked himself out of his big idea for very small solar cells—so small they could be turned into a transparent spray that could be applied to windows the way tint is applied to car windshields and sunglasses. The 32-year-old Yorkshire-born Brit was doing postdoctoral research in Bergen, Norway, when he revisited a notion he'd been mulling for years—that metal nanoparticles, bits of matter thousands of times smaller than the width of a human hair, could be used to create a thin solar film. "If it was a good idea, someone would have done it before me," Denby says of his thinking at the time. A colleague encouraged Denby to pursue it anyway, and now his five-person, Bergen-based development shop, EnSol, has a patent pending for the spray.
At 250 nanometers, EnSol's solar film is 800 times thinner than the silicon wafers that are used to make traditional solar cells, and dozens of times thinner than other solar films on the market. Using standard industrial coating techniques, EnSol's product could be applied to almost any surface, from windows to roof tiles—potentially turning whole buildings into solar panels. The cells could be manipulated to appear in any color. Denby won't say which metals EnSol uses, only that he says they are cheap and nontoxic.
With an initial grant of about $75,000 from the Research Council of Norway, Denby recruited Chris Binns, a nanotech specialist at the University of Leicester in Britain, to help produce sample cells. So far the two have been able to make only a few square centimeters of film at a time. "We've got this stuff, we shine light on it, and it produces a current," says Binns. The next step is to test the film's efficiency, the rate at which it captures sunlight. Commercial silicon cells average around 15 percent efficiency; EnSol is aiming for 20 percent and hopes to have a product ready for the market by 2016.
Robert W. Birkmire, director of the Institute of Energy Conversion at the University of Delaware, says that may be a challenge. "To actually make something that's marketable is a long road to hell," he says. Denby, now in talks with venture-capital firms, is making no guarantees. "It's very early in the day to say anything definite," he says. Denby wants to be sure investors are willing to stick with his idea. "It could be huge," he says. "I'm sort of a naïve scientist and would like to see a better world for everybody."
PhD in nanoscience from University of Manchester in Britain
EnSol, a five-person research outfit in Bergen, Norway
Transparent solar-cell film applied through a spray