Nav: Home

Researchers gain key insight into solar material's soaring efficiency

May 22, 2019

The rows of blue solar panels that dot landscapes and rooftops are typically made out of crystalline silicon, the workhorse semiconductor found in virtually every electronic device.

Over the last decade, Colorado State University researchers have led pioneering studies into improving the performance and cost of solar energy by fabricating and testing new materials that extend beyond the capabilities of silicon. They have focused on a material that shows promise for replacing silicon, called cadmium telluride.

In collaboration with partners at Loughborough University in the United Kingdom, researchers at CSU's National Science Foundation-supported Next Generation Photovoltaics Center have reported a key breakthrough in how the performance of cadmium telluride thin-film solar cells is improved even further by the addition of another material, selenium. Their results were published in the journal Nature Energy earlier this month and are the subject of a "News and Views" article.

"Our paper goes right to the fundamental understanding of what happens when we alloy selenium to cadmium telluride," said Kurt Barth, a director of the Next Generation Photovoltaics Center and an associate research professor in the Department of Mechanical Engineering.

Until now, it was not well understood why the addition of selenium has clocked record-breaking cadmium telluride solar cell efficiency - the ratio of energy output to light input - of just over 22 percent. Together with CSU collaborators W.S. Sampath and Amit Munshi, Barth and an international team have solved that mystery. Their experiments revealed that selenium overcomes the effects of atomic-scale defects in cadmium telluride crystals, providing a new path for more widespread, less expensive solar-generated electricity.

The cadmium telluride thin films that the CSU team makes in the lab use 100 times less material than conventional silicon solar panels. They are thus easier to manufacture, and they absorb sunlight at nearly the ideal wavelength. Electricity produced by cadmium telluride photovoltaic cells is the lowest-cost available in the solar industry, undercutting fossil fuel-based sources in many regions of the world.

According to the paper, electrons generated when sunlight hits the selenium-treated solar panel are less likely to be trapped and lost at the material's defects, located at the boundaries between crystal grains as they are grown. This increases the amount of power extracted from each solar cell. Working with materials fabricated at CSU via advanced deposition methods, the team discovered this unexpected behavior by measuring how much light is emitted from selenium-containing panels.

As selenium is not evenly distributed across the panels, they compared luminescence emitted from areas where there was little-to-no selenium present and areas where the selenium was very concentrated.

"Good solar cell material that is defect-free is very efficient at emitting light, and so luminesces strongly," said Tom Fiducia, the paper's lead author and a Ph.D. student at the University of Loughborough, working with Professor Michael Walls. "It is strikingly obvious when you see the data that selenium-rich regions luminesce much more brightly than the pure cadmium telluride, and the effect is remarkably strong."
-end-
The National Science Foundation has supported the work of CSU's Next Generation Photovoltaics Center since 2009.

Colorado State University

Related Solar Cell Articles:

Experiments show dramatic increase in solar cell output
Researchers at MIT and Princeton have found a way to increase the output of silicon solar cells by allowing a single photon to release two electrons in the silicon.
Winds of change...Solar variability weakens the Walker cell
An international team of researchers has found robust evidence for signatures of the 11-year sunspot cycle in the tropical Pacific.
Improving solar cell efficiency with a bucket of water
Beth Parks has devised an astonishingly simple way to overcome a limitation of solar cells -- a bucket of water.
Solar panels for yeast cell biofactories
In a study in Science, a multidisciplinary team led by Core Faculty member Neel Joshi and Postdoctoral Fellows Junling Guo and Miguel Suástegui at Harvard's Wyss Institute for Biologically Inspired Engineering and John A.
A solar cell that does double duty for renewable energy
Researchers at the US Department of Energy's Lawrence Berkeley National Laboratory and the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, have developed an artificial photosynthesis device called a ''hybrid photoelectrochemical and voltaic (HPEV) cell'' that turns sunlight and water into two types of energy - hydrogen fuel and electricity.
More Solar Cell News and Solar Cell Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...