Good Day Sunshine

Get ready for spray-on sunshine. Scientists at the University of South Florida have created some of the world's tiniest solar cells, about one-quarter the size of a grain of rice. The minuscule proportions potentially offer a huge advantage over traditional solar technology. Ordinary silicon solar cells (like the ones used in rooftop arrays) are brittle and wafer-like, limiting their applications. In contrast, the new, tiny cells are made from an organic polymer that can be dissolved into liquids, allowing them to be sprayed or painted onto virtually any flexible surface.

For manufacturers, applying these cells could be as simple and inexpensive as screenprinting, says Xiaomei Jiang, the project's lead researcher. Once perfected, the technology could be used directly on electronic devices such as iPods and cell phones-or even sprayed onto your backpack, which could then function as a kind of miniature power plant for the devices inside. First, however, Jiang must figure out how to give the cells more power. In initial tests, an array of 20 cells produced only 7.8 volts. But Jiang is beefing up their capabilities and says they could be commercially available in the next year or two.