“Fool’s gold” is pretty smart for solar cells
Fool’s gold may not live up to its name after all. Iron pyrite – aka iron sulfide – has been mistakenly overlooked as an efficient solar cell material
for too long, according to researchers at
Oregon State University in Corvallis, who
took a closer look at its properties and
uncovered a promising alternative to
today’s thin-film materials.
of pyrite, formulated a few design rules
that preserved the favorable aspects of
pyrite, and identified Fe2SiS4 and Fe2GeS4
as new absorber candidates,” Keszler said.
This relatively new approach to materials science is known as inverse design.
“As experimentalists, we work very
closely with theory groups at the National
Renewable Energy Lab [in Golden] and
the University of Colorado to first extract
design rules from a combination of high-
level calculations and chemical princi-
ples,” Keszler said. “We then go to the
lab to make new materials and examine
their physical properties.”
Iron, silicon and sulphur are among
the three most available and low-cost
elements on Earth, and, thanks to their
high absorption coefficients, much less
of the material is required. This means
that they can be used in thin-film devices,
which can be fabricated at low cost.
The results of the study were published
Aug. 10, 2011, in the online edition of
Advanced Energy Materials.
But despite the many promising findings, Keszler and his colleagues are not
fooled – they acknowledge that much
work remains to be done. In fact, Keszler
said, a marketable alternative to traditional solar cell materials is still about
10 years off.
“The quality of Fe2SiS4 and Fe2GeS4
needs to continue to improve so that fun-
damental, intrinsic performance can be es-
tablished,” he said. “Appropriate contacts
need to be developed, and integration
issues with respect to cell fabrication
need to be addressed.”
The group is working on advancing
thin-film quality so the properties and
performance of the materials can be
benchmarked against theoretical predic-
tions. They also are looking to refine
design rules so that other materials with
promise for higher performance in solar
cells can be identified. l
This iron germanium sulfide thin-film solar absorber could be a promising new technology for solar energy.
Courtesy of Betterton Design.