Researchers at Georgia Tech are experimenting with similar fiber-based organic solar cells. Zhong Lin Wang, professor of materials science and engineering at the university, says the approach has “major advantages” over conventional flat-cell designs. His lab has developed a hybrid cell consisting of optical fibers and a nanowire fuzz made of zinc oxide that is grown on the outside walls of the fibers. The nanowires, treated with light-absorbing dyes, are meant to provide a greater surface area for capturing sunlight. Wang says this approach enhances efficiency by a factor of six, though his lab has yet to go beyond a single fiber strand. “We are still working on integrating multiple fibers [on a larger surface],” he says.
Carroll started his research back in 2004, giving Wake University a head start on the path to commercialization. “Most of the devices out there now are on individual fibers,” he says. Carroll also says there’s no shortage of roll-to-roll processing techniques on the market that could make substrates covered with optical fibers. “We’ll be borrowing from those; this isn’t difficult to do,” he says. “Sensitivity to film thickness and coatings quality is much less than we had anticipated, meaning that manufacturing routes are much closer than we first anticipated.”
FiberCell is currently talking with investors and aims to produce its fiber-based organic cells for roof tiles and other products that would benefit from the ability to accept light from different angles “If I get this to perform near its maximum, then I have a device that should theoretically be able to surpass 15 percent efficiency, approaching 20 percent,” Carroll says. This would make organic photovoltaic technology competitive with today’s top silicon panels.
John Paul Morgan, an optical engineer and chief technology officer of concentrated photovoltaic solar company Morgan Solar, says the FiberCell approach will have to compete with other techniques designed to increase panel surface area and trap more light. Growing a forest of tightly grouped nanowires on top of a substrate, for example, has been shown to improve the efficiency of organic cells.
“Optical fibers are an interesting approach, but like other approaches it comes down to the challenges of fabrication,” said Morgan. “All new cell technologies face issues with moisture, electrical connections, wear and tear. If they can overcome these, then this could be a very viable idea. I’m excited to see what comes next.”