Flexible silicon solar-cell fabrics may soon be reality

The findings by an international team of chemists, physicists and engineers, led by John Badding, a professor of chemistry at Penn State, will be posted by the journal Advanced Materials in an early online edition and will be published on a future date in the journal's print edition.

The team's new findings build on earlier work addressing the challenge of merging optical fibers with electronic chips -- silicon-based integrated circuits that serve as the building blocks for most semiconductor electronic devices such as solar cells, computers and cellphones.

Rather than merge a flat chip with a round optical fiber, the team found a way to build a new kind of optical fiber -- which is thinner than the width of a human hair -- with its own integrated electronic component, thereby bypassing the need to integrate fiber-optics with chips. To do this, they used high-pressure chemistry techniques to deposit semiconducting materials directly, layer by layer, into tiny holes in optical fibers.

Now, in their new research, the team members have used the same high-pressure chemistry techniques to make a fiber out of crystalline silicon semiconductor materials that can function as a solar cell -- a photovoltaic device that can generate electrical power by converting solar radiation into direct-current electricity.

"Our goal is to extend high-performance electronic and solar-cell function to longer lengths and to more flexible forms. We already have made meters-long fibers but, in principle, our team's new method could be used to create bendable silicon solar-cell fibers of over 10 meters in length," Badding said.

"Long, fiber-based solar cells give us the potential to do something we couldn't really do before: We can take the silicon fibers and weave them together into a fabric with a wide range of applications such as power generation, battery charging, chemical sensing and biomedical devices."

Badding explained that one of the major limitations of portable electronics such as smartphones and iPads is short battery life. Solar-boosted batteries could help solve this problem. "A solar cell is usually made from a glass or plastic substrate onto which hydrogenated amorphous silicon has been grown," Badding explained.

"Such a solar cell is created using an expensive piece of equipment called a PECVD (plasma-enhanced chemical vapor deposition) reactor and the end result is something flat with little flexibility. But woven, fiber-based solar cells would be lightweight, flexible configurations that are portable, foldable and even wearable."

“This material could then be connected to electronic devices to power them and charge their batteries. The military especially is interested in designing wearable power sources for soldiers in the field," Badding added.