Weed Could Bring Affordable Solar Power Worldwide

Purple pokeberry power (Photo: Muffet on Flickr)

Never underestimate the power of weeds. Case in point: the common pokeberry weed - native to North America, South America, East Asia and New Zealand and whose red dye was once used by American Civil War soldiers to write letters home - may now hold the secret for revolutionizing the next generation of low-cost photovoltaic cells, making widespread, affordable homegrown solar power a real possibility, especially for developing nations.
Researchers at Wake Forest University's Center for Nanotechnology and Molecular Materials were able to create a more efficient fiber-based solar cell by coating the solar cell's fibers with the pokeberry dye, which helps the fibers absorb more sunlight.

Coupled with the humble pokeberry's red dye, the fiber-based solar cells generate twice as much power than current thin-film technology. And what's even better is that the pokeberry can grow anywhere, including dry and inhospitable places.

"They're weeds," says the center's director Dr. David Carroll. "They grow on every continent but Antarctica."

With their spin-off company FiberCell Inc., Wake Forest is now developing these fiber-based solar cells for the commercial market.

So how does a fiber-based solar cell work?
Made of millions of tiny, plastic cylinders or fibers that trap sunlight until it is absorbed, this configuration means that a fiber-based cell can collect light at any angle, from sunrise to sunset because there is much more surface area available.

To manufacture these highly-efficient 'hybrid' cells, the plastic fibers are stamped onto plastic sheets and the absorber dye (this is where cheap and locally-grown pokeberries come in) is sprayed on. The sheets are flexible, which means that manufacturers can make them and ship them at a low cost to developing countries. Once there, local factories can spray the absorbent pokeberry dye on the cells.

Dr Carroll points out that compared to a plant making flat-cell solar panels, which would cost about $15 million, a fiber-based solar cell finishing plant would only cost $5 million, which would make this kind of solar power much more accessible.

"We could provide the substrate," says Carroll. "If Africa grows the pokeberries, they could take it home.

"It's a low-cost solar cell that can be made to work with local, low-cost agricultural crops like pokeberries and with a means of production that emerging economies can afford."

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