(Press-News.org) GAINESVILLE, Fla. — Doping may be a no-no for athletes, but researchers in the University of Florida's physics department say it was key in getting unprecedented power conversion efficiency from a new graphene solar cell created in their lab.
Graphene solar cells are one of industry's great hopes for cheaper, durable solar power cells in the future. But previous attempts to use graphene, a single-atom-thick honeycomb lattice of carbon atoms, in solar cells have only managed power conversion efficiencies ranging up to 2.9 percent. The UF team was able to achieve a record breaking 8.6 percent efficiency with their device by chemically treating, or doping, the graphene with trifluoromethanesulfonyl-amide, or TFSA. Their results are published in the current online edition of Nano Letters.
"The dopant makes the graphene film more conductive and increases the electric field potential inside the cell," said Xiaochang Miao, a graduate student in the physics department. That makes it more efficient at converting sunlight into electricity. And unlike other dopants that have been tried in the past, TFSA is stable — its effects are long lasting.
The solar cell that Miao and her co-workers created in the lab looks like a 5-mm-square window framed in gold. The window, a wafer of silicon coated with a monolayer of graphene, is where the magic happens.
Graphene and silicon, when they come together, form what is called a Schottky junction — a one-way street for electrons that when illuminated with light, acts as the power conversion zone for an entire class of solar cells. Schottky junctions are commonly formed by layering a metal on top of a semiconductor. But researchers at the UF Nanoscience Institute for Medical and Engineering Technologies discovered in 2011 that graphene, a semi-metal, made a suitable substitute for metal in creating the junction.
"Graphene, unlike conventional metals, is transparent and flexible, so it has great potential to be an important component in the kind of solar cells we hope to see incorporated into building exteriors and other materials in the future," said Arthur Hebard, distinguished professor of physics at UF and co-author on the paper. "Showing that its power-converting capabilities can be enhanced by such a simple, inexpensive treatment bodes well for its future."
The researchers said that if graphene solar cells reach 10 percent power conversion efficiency they could be a contender in the market place, if production costs are kept low enough.
The prototype solar cell created in the UF lab was built on a rigid base of silicon, which is not considered an economical material for mass production. But Hebard said that he sees real possibilities for combining the use of doped graphene with less expensive, more flexible substrates like the polymer sheets currently under development in research laboratories around the world.
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Credits
Writer
Donna Hesterman , donna.hesterman@ufl.edu, 352-846-2573
Source
Arthur Hebard, afh@ufl.edu, 352-222-6212
Source
Xiaochang Miao, xxmiaophy@gmail.com, 352-871-4116
CHICAGO--- Scars left behind by childhood cancer treatments are more than skin-deep. The increased risk of disfigurement and persistent hair loss caused by childhood cancer and treatment are associated with emotional distress and reduced quality of life in adulthood, according to a new study led by a Northwestern Medicine advanced practice nurse, Karen Kinahan, and based on data from the Childhood Cancer Survivor Study (CCSS).
The largest study of its kind, published May 21 in the Journal of Clinical Oncology, compared scarring, disfigurement and persistent hair loss ...
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Such materials could find applications in solar cells, light emitting diodes ...
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Bud has now become the first hurricane of the eastern Pacific Hurricane Season, as NASA visible and infrared satellite imagery revealed an organized structure of spiraling thunderstorms around the eye. Watches and warnings are already in effect for southwestern Mexico as Bud nears.
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EAST LANSING, Mich. — A new study testing the benefits of a virtual exercise partner shows the presence of a moderately more capable cycling partner can significantly boost the motivation – by as much as 100 percent – to stick to an exercise program.
The research out of Michigan State University's Department of Kinesiology shows women taking part in cycling exercises exercised twice as long when working with a virtual partner, results the authors said can be used to help people meet physical activity recommendations.
The work by Brandon Irwin and colleagues is published ...
When it comes to holding children accountable for crimes they commit, race matters.
According to a new study by Stanford psychologists, if people imagine a juvenile offender to be black, they are more willing to hand down harsher sentences to all juveniles.
"These results highlight the fragility of protections for juveniles when race is in play," said Aneeta Rattan, lead author of the study, which appears this week in the journal PLoS ONE.
Historically, the courts have protected juveniles from the most severe sentences. It has been recognized that children are different ...
Chinese researchers have designed and tested simulations of a "nanoclutch," a speed regulation tool for nanomotors. The nanoclutch consists of two carbon nanotubes (CNTs), one inside the other, separated by a film of water. Electrowetting forces control the friction between the water and the inner and outer walls of the CNTs. When the two tubes are electrically charged, the water confined between them can transmit the torque from the inner tube to the outer tube, and the device is said to be in the engaged state. When the CNTs are uncharged, the device is in the disengaged ...
Scientists at the Georgia Institute of Technology achieved a 17-percent increase in boiling efficiency by using an acoustic field to enhance heat transfer. The acoustic field does this by efficiently removing vapor bubbles from the heated surface and suppressing the formation of an insulating vapor film. As reported in the American Institute of Physics' (AIP) journal the Physics of Fluids, bubble removal was enhanced because the acoustic field induces capillary waves on the bubble, causing its contact line to contract and detach the bubble from the surface. The mechanisms ...
Researchers from Vestfold University College in Norway have created a simple, efficient energy harvesting device that uses the motion of a single droplet to generate electrical power. The new technology could be used as a power source for low-power portable devices, and would be especially suitable for harvesting energy from low frequency sources such as human body motion, write the authors in a paper accepted to the American Institute of Physics' (AIP) journal Applied Physics Letters. The harvester produces power when an electrically conductive droplet (mercury or an ionic ...
NASA's next flagship mission — the James Webb Space Telescope — will carry the largest primary mirror ever deployed. This segmented behemoth will unfold to 21.3 feet in diameter once the observatory reaches its orbit in 2018.
A team of scientists at NASA's Goddard Space Flight Center in Greenbelt, Md., now is developing an instrument that would image and characterize planets beyond the solar system possibly from a high-altitude balloon has borrowed a page from the Webb telescope's playbook. It has created an infinitely smaller segmented mirror that currently measures ...
