The performance of cadmium telluride (CdTe) thin-film
solar cells has improved in terms of efficiency by the addition of selenium in
ground-breaking research. The blue solar panels that are on the rooftops and
landscapes are made out of this semiconductor – crystalline silicon, which is
also found in many electronic devices.
A research team from the Georgia Institute of
Technology, the University of California San Diego and the Massachusetts
Institute of Technology has discovered that adding alkali metal to perovskite
solar cells could enable energy devices to last longer and maintain better
performance.
“Perovskites could really change the game in solar,”
David Fenning, a professor of nanoengineering at the University of California
San Diego, said in a statement. “They have the potential to reduce costs
without giving up performance. But there's still a lot to learn fundamentally
about these materials.”
Over the last decade, the researchers from Colorado
State University (CSU) have led pioneering studies to advance the performance
and reduce the cost of solar energy. They have tried fabricating and testing
new materials that usually extend beyond the capabilities of silicon. They
focused on a material that has shown promise for replacing the semiconductor –
it’s called cadmium telluride (CdTe).
In a key breakthrough, the researchers at CSU’s
National Science Foundation in collaboration with partners at Loughborough
University, United Kingdom, supported Next Generation Photovoltaics Centre and
they came up with how the performance of CdTe thin-film solar cells is improved
further by the addition of selenium. The result of the research was also
published recently in the journal, Nature Energy. In the context, Kurt Barth, a
director of the Next Generation Photovoltaics Centre and an associate research
professor in the Department of Mechanical Engineering said that their paper
goes right to the fundamental understanding of what happens when selenium is
alloyed to CdTe.
The CSU collaborators W.S. Sampath and Amit Munshi,
together with Barth and an international team could solve why the addition of
selenium clocked record-breaking CdTe solar cell efficiency – the ratio of
energy output to light input of over 22%. Their experiments highlighted that
selenium overcomes the effects of atomic-scale defects in cadmium telluride
crystals. And the results also provided a new path for widespread less
expensive solar-generated electricity.
Meanwhile, the paper also highlights that electrons
generated when sunlight hits the solar panel that is selenium-treated are less
prone to get trapped and lost at the material’s defects, located at the
boundaries between crystal grains. This increases the amount of power extracted
from the solar cells. Working with materials fabricated at CSU via advanced
deposition methods, the team discovered this unexpected behaviour by measuring
how much light is emitted from selenium-containing panels.
In the context, Tom Fiducia, the paper’s lead author
and a PhD student at the University of Loughborough, working with Professor
Michael Walls stated that good solar cell material that is defect-free is very
efficient at emitting light. It has also been reported that the National
Science Foundation has supported the work of CSU’s Next Generation Photovoltaics
Centre since 2009.
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