Solar cells based on cadmium and tellurium could move closer to theoretical levels of efficiency because of some sleuthing by researchers at the Department of Energy's Oak Ridge National Laboratory.
A team led by Jonathan Poplawsky of the Center for Nanophase Materials Sciences used advanced microscopy techniques to discover efficiency differences of crystalline structures of various mixtures of cadmium, tellurium and selenium. In fact, selenium is an integral part of the formulation that resulted in a world record for solar cell efficiency. The team's paper is published in Nature Communications.
While some of today's solar cells use a blend of cadmium and tellurium to convert light into electricity, adding the optimum amount of selenium in the right places could help increase efficiency from the current mark of about 22 percent to levels approaching the theoretical limit of 30-33 percent. The trick is to determine the best ratio of selenium.
"Using different microscopy methods, we were able to gain a better understanding of the phases, compositions and crystalline structures that allow these materials to convert light into electricity more efficiently," said Poplawsky, adding that the availability of data is limited. "In some instances, adding too much selenium changes the crystalline structure of cadmium-tellurium and dramatically reduces the conversion efficiency."
For this study, researchers studied four solar cells with different selenium contents - and corresponding changes in crystal structure - and learned that the one with the highest level of selenium did not perform well. Neither did the one with the lowest selenium content. The alloy composition that performed best consisted of approximately 50 percent cadmium, 25 percent tellurium and 25 percent selenium.
To make their determination, researchers used a combination of analytical techniques, including atom probe tomography, transmission electron microscopy and electron beam induced current. These are capabilities within the CNMS, a DOE Office of Science User Facility.
"We have shown that the amount of selenium incorporated into the cadmium-tellurium controls whether the small crystals inside the solar cell form as crystal structure A or crystal structure B," Poplawsky said. "This information can be used as a roadmap for solar cell producers to make improved cadmium-tellurium solar cells that use selenium additions, and hopefully increase the overall efficiency."
Poplawsky noted that solar panels typically use silicon as the material for converting sunlight into electricity. Cadmium-telluride, however, has an advantage over silicon because it can absorb the same amount of sunlight with 98 percent less semiconducting material, thus reducing the overall cost of the solar panel. This also makes solar panels composed of cadmium, tellurium and selenium more competitive with other forms of electricity generation.
ORNL co-authors of the paper, titled "Structure and Compositional Dependence on the CdTexSe1-x Alloy Layer Photoactivity in CdTe-based Solar Cells," are Wei Guo, Karren More and Donovan Leonard.
This research was funded by DOE's SunShot Initiative in collaboration with the National Sciences Foundation.
UT-Battelle manages ORNL for the DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.
About the SunShot Initiative
The SunShot Initiative is a collaborative national effort that aggressively drives innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, the Energy Department supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour. Learn more at energy.gov/sunshot.
Cutline: The entire solar material for the sample with less than or equal to 30 percent selenium is photoactive (top) while the bottom of the solar material for the image below contains greater than 35 percent selenium and has reduced photoactivity.
NOTE TO EDITORS: You may read other press releases from Oak Ridge National Laboratory or learn more about the lab at http://www.
Twitter - http://twitter.
RSS Feeds - http://www.
Ron Walli | EurekAlert!
ISFH-CalTeC is “designated test centre” for the confirmation of solar cell world records
16.01.2018 | Institut für Solarenergieforschung GmbH
A water-based, rechargeable battery
09.01.2018 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
16.01.2018 | Materials Sciences
16.01.2018 | Materials Sciences
16.01.2018 | Power and Electrical Engineering