Next Solar Cells Could Rely on Nanoflower Power
The germanium sulfide "nanoflowers" have petals only 20-30 nanometers thick, and provide a large surface area in a small amount of space.
CREDIT: North Carolina State University
Microscopic crystalline "flowers" could lead to next-generation batteries and solar power cells, researchers say.
Materials scientists have created flowerlike structures from incredibly thin petals of germanium sulfide, a cheap, nontoxic material that is very good at absorbing solar energy and converting it to electricity. Scientists reasoned that flowers of germanium sulfide would be much better than flat panels at capturing light, since the many flower petals would provide far more surface area in the same amount of space.
To create the flowerlike structures, scientists first heat germanium sulfide powder in a furnace until it starts to vaporize. This gas is then blown into a cooler area, where it solidifies as a crystalline sheet only about 30 nanometers (billionths of a meter) wide – about 15 times thicker than a molecule of DNA.
As the researchers grow these layers of germanium sulfide in stacks atop each other, they branch out from one another. The result is a pattern of crystalline petals similar to a carnation's or marigold's – flowerlike structures about 100 microns in diameter, or the width of a human hair.
Past research has suggested germanium sulfide is also good at energy storage — for example, in latching onto and getting electricity from the chemicals used in the rechargeable lithium ion batteries now found in many mobile devices. As such, these crystalline nanoflowers could help lead to improved batteries, serving as scaffolds with an extraordinary amount of surface area where electricity-generating reactions can take place.
"Energy storage can be an even more interesting application than solar cells for germanium sulfide nanoflowers," researcher Linyou Cao, a materials scientist at North Carolina State University, told TechNewsDaily.
One might imagine rows of these flowers placed on the surfaces of sheets that get rolled up to fit within batteries.
"We're now working to demonstrate the exceptional capabilities of these nanoflowers in energy storage," Cao said.
The researchers also are exploring other materials. "Nanoflowers made of molybdenum sulfide could be even better for energy storage," Cao said.
The scientists detailed their findings online Sept. 25 in the journal ACS Nano.