Wrinkles and twists boost power from solar panels

Wrinkles and twists boost power from solar panels Taking their cue from the humble leaf, researchers have used microscopic folds on the surface of photovoltaic material to significantly improve the power output of flexible, low-cost solar cells. "Everything hinges on the fact that you can reproduce the wrinkles and folds," Loo said. But the folding technique increased absorption at this end of the spectrum by roughly 600%, the researchers found. "If you look at the solar spectrum, there is a lot of sunlight out there that we are wasting," Loo said. Loo said the researchers drew their inspiration from leaves. Its green surface is perfectly constructed to bend and control light to make certain that a maximum amount of solar energy is absorbed to create energy and nutrients for the tree. Recent work by Pilnam Kim, a postdoctoral researcher in Stone's lab, provided insight into how these microscopic structures could be applied to synthetic devices. The shallower ripples were classified as wrinkles and the deeper ones are called folds. The team found that a surface containing a mix of wrinkles and folds produced the very best results. "If you look at leaves very closely, they are not smooth, they have these sorts of structures," said Loo, who is deputy director of Princeton's Andlinger Center for Energy and the Environment. In addition to Loo, the researchers included: Howard Stone, the Donald R. Dixon Professor in Mechanical and Aerospace Engineering at Princeton, Jason Fleischer, an associate professor of electrical engineering at Princeton, Jong Bok Kim, Pilnam Kim, and Nicolas Pégard, a graduate student in Princeton's electrical engineering department; Soog Ju Oh, and Cherie Kagan, of the University of Pennsylvania. And that leads to a greater chance of the light's being absorbed. The research team's work involves photovoltaic systems made of relatively cheap plastic. So far, plastic panels have not been practical for widespread use because their energy production has been too low. Support for the research was delivered by the Office of Naval Research, the National Science Foundation, including those through the Princeton Center for Complex Materials, the Air Force Office of Scientific Research, and the Curtin-Stafford Fund at Princeton. In most cases, researchers have focused on increasing the efficiency of the plastic photovoltaic material itself. 6% efficiency. "It is flexible, bendable, light weight and low cost," Loo said. "On a flat surface, the light either is absorbed or it bounces back," said Loo, a professor of chemical and biological engineering at Princeton. A standard plastic panel's energy production would be diminished by 70 percent after undergoing bending. Although the technique results in an overall increase in efficiency, the results were particularly significant at the red side of the light spectrum, which has the longest wavelengths of visible light. Wrinkles and twists boost power from solar panels Trade News selected by Local Linkup on 30/04/2012