Researchers Create Organic Photovoltaic Panels From Graphene

Despite the fact that graphene has been known to exist for decades, only recently have researchers begun to study graphene in earnest. The reason for the relatively late start into research using grapheme is that the material was difficult to make in quantities needed for research.

Once that hurdle was overcome, researchers quickly started to use graphene in all manner of study for a variety of uses. Graphene is being studied for use in semiconductors as a multiplier able to make processors many times faster than what we have access to today. Researchers are still studying better and cheaper methods of making grapheme and one important method was discovered in October of 2009 for growing graphene.

A team of researchers at the University of Southern California has discovered a way to use graphene to produce a flexible, printable sheet only four or less atoms thick. These graphene sheets can then be bound to a flexible polymer sheet to create a new type of organic photovoltaic cell or solar panel.

The resulting solar panel is thin and very flexible and the team believes that the material may one day be used for creating clothing that can generate power when worn in the sun. The big advantage of the graphene solar panel is that it is very flexible, much more so than existing solar panel materials.

“Organic photovoltaic (OPV) cells have been proposed as a means to achieve low cost energy due to their ease of manufacture, light weight, and compatibility with flexible substrates,” wrote Chongwu Zhou, a professor of electrical engineering in the USC Viterbi School of Engineering, in a paper recently published in the journal ACS Nano.

The team creates the flexible graphene sheets needed for the solar panels by chemical vapor deposition. Carbon atoms are deposited in the form of graphene films onto a nickel plate from a methane gas. After the molecules are deposited, a thin protective layer of thermo plastic covers them. After the protective layer is deposited, the nickel plate is dissolved in an acid bath.

The left over film is very flexible and can be incorporated into an OPV. The downside to an OPV compared to a traditional solar panel made of silicon is that the OPV is able to convert less solar radiation into electricity.

“For every 1000 watts of sunlight that hits a one square meter area of the standard silicon solar cell, 14 watts of electricity will be generated,” says Lewis Gomez De Arco, a doctoral student and a member of the team that built the graphene OPVs. “Organic solar cells are less efficient; their conversion rate for that same one thousand watts of sunlight in the graphene-based solar cell would be only 1.3 watts.”

The team thinks that in the future these OPV sheets could be made into a fabric that could be hung like curtains or worn as clothing that can generate power. Another interesting use would be to cover the seats in an electric car or hybrid with the material to help capture power for the vehicles battery systems.

www.dailytech.com

Asthetically Pleasing Solar Cells Save Energy

Solar engineers have long sought to develop an energy-generating glazing that is as capable of producing power as it is easy on the eyes. The feat may just have been accomplished by The Center for Architecture Science and Ecology (CASE), who have developed a concentrating solar system that is not only modern and attractive but extremely efficient and cost effective. The system is made up of rows of pyramid-shaped glass receptors that move with sulight throughout the day, magnifying the incoming light and capturing it in a small photovoltaic cell located in the center of each pyramid.

CASE’s receptors can be fitted to existing buildings or built into new designs. The concentrating solar cells are strung on wires with tracking mechanisms that turn the receptors in the direction of the sun throughout the day. Since they are made from glass they are transparent and allow light to pass through windows, which makes them perfect for adding solar power to building facades while maximizing available daylight.

The glass pyramid shape actually serves to magnify light and increase the natural lighting inside a building while decreasing the need for artificial light. The design is also meant to capture thermal energy trapped inside the glass pyramids that is not converted into electricity to be used for heating and cooling systems.

The receptors aren’t commercially available just yet, but a manufacturer has been lined up and the hope is to bring these cells to market as soon as the manufacturing process is finalized. The estimated cost return is less than two and a half years in a sunny place like Los Angeles and less than a decade in a foggy place like San Francisco.

www.case.rpi.edu