Article published on www.sciencedaily.com October 11, 2012
Researchers from North Carolina State University have created
flower-like structures out of germanium sulfide (GeS) -- a semiconductor
material -- that have extremely thin petals with an enormous surface
area. The GeS flower holds promise for next-generation energy storage
devices and solar cells.
"Creating these GeS nanoflowers is exciting because it gives us a
huge surface area in a small amount of space," says Dr. Linyou Cao, an
assistant professor of materials science and engineering at NC State and
co-author of a paper on the research. "This could significantly
increase the capacity of lithium-ion batteries, for instance, since the
thinner structure with larger surface area can hold more lithium ions.
By the same token, this GeS flower structure could lead to increased
capacity for supercapacitors, which are also used for energy storage."
To create the flower structures, researchers first heat GeS powder in
a furnace until it begins to vaporize. The vapor is then blown into a
cooler region of the furnace, where the GeS settles out of the air into a
layered sheet that is only 20 to 30 nanometers thick, and up to 100
micrometers long. As additional layers are added, the sheets branch out
from one another, creating a floral pattern similar to a marigold or
carnation.
"To get this structure, it is very important to control the flow of
the GeS vapor," Cao says, "so that it has time to spread out in layers,
rather than aggregating into clumps."
GeS is similar to materials such as graphite, which settle into neat
layers or sheets. However, GeS is very different from graphite in that
its atomic structure makes it very good at absorbing solar energy and
converting it into useable power. This makes it attractive for use in
solar cells, particularly since GeS is relatively inexpensive and
non-toxic. Many of the materials currently used in solar cells are both
expensive and extremely toxic.
The paper, "Role of Boundary Layer Diffusion in Vapor Deposition
Growth of Chalcogenide Nanosheets: The Case of GeS," is published online
in the journal ACS Nano. The paper was co-authored by Cao; Dr.
Chun Li, a former postdoctoral researcher at NC State, now a professor
at the University of Electronic Science and Technology of China; Liang
Huang, a former visiting Ph.D. student at NC State; Gayatri Pongur
Snigdha, a former undergraduate student at NC State; and Yifei Yu, a
Ph.D. student at NC State. The work was supported by the U.S. Army
Research Office.
Find more about innovation on PV sector at www.ciel-et-terre.net/floating-solar-system/
Find more about innovation on PV sector at www.ciel-et-terre.net/floating-solar-system/