Breakthrough: 'Light Pipes' Increase the Performance of Organic Solar Cells by More than 100%

fibercell diagram image

Image: FiberCell
These Organic Cells Could Theoretically Surpass 15% Efficiency
Organic solar cells are promising, but up to now, their low efficiency (sub-10%) has meant that they are not quite cost-effective in most applications. But this might change thanks to a breakthrough by FiberCell, a spinoff company that was created by Wake Forest University researchers. How did they make organic solar cells more efficient? They figured out how to have the cells capture more light by stamping optical fibers onto the polymer substrate that forms the foundation of the cell. These fibers, which they call 'light pipes', are perpendicular to the cell and literally pipe in sunlight. Read on for the details.
fibercell diagram image

Image: FiberCell

The beauty of the light pipes is that sunlight can enter the tip of a fiber at any angle and then bounce around until it is absorbed by the organic solar cell.

The best organic solar cells today are nearly 8 percent efficient, although efforts are ongoing to develop organic chemistries that would push the efficiency of such cells above 10 percent. But [David Carroll, professor of physics at Wake Forest University,] says improved chemistries alone won't be enough to catch up to the performance of silicon cells. "The answer doesn't lie in chemistry--it lies in the architecture of the cell itself," he says. [...]

The researchers tested a glass fiber cell in the lab and found that the fiber enhanced light absorption by about half. Carroll says that the cells can also produce twice as many watt-hours over the course of a day compared to flat panels because they can receive light from different angles. "It's the same thing as taking a flat device and pointing it directly at the sun all day long," he says. (source)

fibercell diagram image

Image: FiberCell

This is very similar conceptually to "hairy" solar panels that we wrote about a while ago. They use nanowires made from exotic materials like gallium arsenide, indium gallium phosphide instead of optical fibers, but the way they absorb light from many angles works the same.

The Future of FiberCell
The company is currently trying to get a cash injection from investors to produce cells for roof tiles and similar products because they are the applications that would benefit most from the "all angles" benefit of the light pipes.

David Caroll says: ""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." That would make these organic solar cells competitive with the best silicon-based solar panels!

Via Technology Review
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