For years, popcorn has remained quiet, biding its time. Once an underachiever, now it’s ready to burst out from the shadows, able to finally give to humanity, prove its worth and save the world. And you thought it was just there to make you feel vaguely queasy after a movie marathon. How wrong you were.
Popcorn is the inspiration for a new technology that looks like it could help make solar cells more efficient, courtesy of the University of Washington.
“By using a popcorn-ball design — tiny kernels clumped into much larger porous spheres — researchers at the University of Washington are able to manipulate light and more than double the efficiency of converting solar energy to electricity,” says the University.
Go popcorn, you buttery charmer!
The popcorn design will let dye-sensitised solar cells get better conversion rates – able to bring them more in line with their silicon counterparts.
Here’s more from Washington:
Dye-sensitized solar cells, first popularized in a scientific article in 1991, are more flexible, easier to manufacture and cheaper than existing solar technologies. Researchers have tried various rough surfaces and achieved higher and higher efficiencies. Current lab prototypes can convert just over one tenth of the incoming sun’s energy into electricity. This is about half as efficient as the commercial, silicon-based cells used in rooftop panels and calculators.
The UW researchers did not attempt to maximize the overall efficiency of a dye-sensitized solar cell to match or beat these previous records. Instead, they focused on developing new approaches and compared the performance of a homogeneous rough surface with a clumping design. One of the main quandaries in making an efficient solar cell is the size of the grains. Smaller grains have bigger surface area per volume, and thus absorb more rays. But bigger clumps, closer to the wavelength of visible light, cause light to ricochet within the thin light-absorbing surface so it has a higher chance of being absorbed.
“You want to have a larger surface area by making the grains smaller,” Cao said. “But if you let the light bounce back and forth several times, then you have more chances of capturing the energy.”
Other researchers have tried mixing larger grains in with the small particles to scatter the light, but have little success in boosting efficiency. The UW group instead made only very tiny grains, about 15 nanometers across. (Lining up 3,500 grains end to end would equal the width of a human hair.) Then they clumped these into larger agglomerations, about 300 nanometers across. The larger balls scatter incoming rays and force light to travel a longer distance within the solar cell. The balls’ complex internal structure, meanwhile, creates a surface area of about 1,000 square feet for each gram of material. This internal surface is coated with a dye that captures the light.
The researchers expected some improvement in the performance but what they saw exceeded their hopes.
“We did not expect the doubling,” Cao said. “It was a happy surprise.”
Greenbang loves a happy ending.