Bulky solar-powered gear is nothing new, but imagine charging your iPod or cell phone while you jog along the beach, read a book in the park, or bike to work invisibly, from the clothing you wear.

Implausible? Not really: Researchers at the University of Southern California's Viterbi School of Engineering have produced flexible transparent carbon atom films that could change the way we collect solar energy.

The USC team's graphene organic photovoltaics, recently discussed in the journal ACS Nano, have a host of benefits: They're flexible, cheap to produce, are easy to manufacture, and they're light-weight. And while they're considerably less efficient than silicon cells, they offer unique applications.

Not the Most Efficient

These new organic photovoltaic (OPV) sheets may be innovative, but they're also inefficient in the grand scheme of PV technology.

According to Lewis Gomez De Arco, a doctoral student and a member of the team that built the graphene OPVs, 1000 watts of solar energy on one square meter of a standard silicon cell will produce 14 watts of electricity, but only 1.3 watts would be produced by a graphene OPV cell.

So how are they made? Researchers mix methane and hydrogen gases to form graphene deposits on a nickel plate. A layer of thermo plastic is applied to protect the graphene, and then the nickel is dissolved in an acid bath. The graphene is attached to a flexible polymer sheet, which is layered into an OPV cell. Graphene is used because it's highly conductive and it's transparent.

Clothing and Curtains That Collect Solar

Though comparatively inefficient, graphene OPVs boast cost effectiveness, flexibility, and the potential for mass production, which translates to opportunities for everyday use at home and on the go.

Gomez De Arco says it may eventually be possible to produce the OPVs similar to the way a newspaper press prints newspapers, and he imagines a variety of applications:

The flexibility of the graphene OPVs is at the core of the technology's potential. Indium-Tin-Oxide OPVs fail at a small angle of bending, according to USC researchers, but the graphene OPVs keep working despite repeated bending at larger stress angles. This flexibility gives graphene OPVs an advantage when it comes to textile applications, such as clothing and curtains.

While you probably won't find solar-collecting shirts on the market anytime soon, this new technology has unlocked the realistic potential for new applications that could transform the way we collect solar energy.

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