Treating cadmium-telluride (CdTe) solar cell materials with cadmium-chloride improves their efficiency, but researchers have not fully understood why. Now, an atomic-scale examination of the thin-film solar cells led by the Department of Energy’s Oak Ridge National Laboratory has answered this decades-long debate about the materials’ photovoltaic efficiency increase after treatment. A research team from ORNL, the University of Toledo and DOE’s National Renewable Energy Laboratory used electron microscopy and computational simulations to explore the physical origins of the unexplained treatment process. The results are published in Physical Review Letters (PRL). Thin-film CdTe solar cells are considered a potential rival to silicon-based photovoltaic systems because of their theoretically low cost per power output and ease of fabrication. Their comparatively low historical efficiency in converting sunlight into energy, however, has limited the technology’s widespread use, especially for home systems. Research in the 1980s showed that treating CdTe thin films with cadmium-chloride significantly raises the cell’s efficiency, but scientists have been unable to determine the underlying causes. ORNL’s Chen Li, first author on the PRL study, explains that the answer lay in investigating the material at an atomic level. “We knew that chlorine was responsible for this magical effect, but we needed to find
The post Atomic switcheroo explains origins of thin-film solar cell mystery has been published on Technology Org.
Like a hungry diner ripping open a dinner roll, a fuel cell catalyst that converts hydrogen into electricity must tear open a hydrogen molecule. Now researchers have captured a view of such a catalyst holding onto the two halves of its hydrogen feast. The view confirms previous hypotheses and provides insight into how to make the catalyst work better for alternative energy uses. This study is the first time scientists have shown precisely where the hydrogen halves end up in the structure of a molecular catalyst that breaks down hydrogen, the team reported online April 22 in Angewandte Chemie International Edition. The design of this catalyst was inspired by the innards of a natural protein called a hydrogenase enzyme. “The catalyst shows us what likely happens in the natural hydrogenase system,” said Morris Bullock of the Department of Energy’s Pacific Northwest National Laboratory. “The catalyst is where the action is, but the natural enzyme has a huge protein surrounding the catalytic site. It would be hard to see what we have seen with our catalyst because of the complexity of the protein.” Ironing Out Expense Hydrogen-powered fuel cells offer an alternative to burning fossil fuels, which generates greenhouse gases. Molecular hydrogen
The post First view of nature-inspired catalyst after ripping hydrogen apart provides insights for better, cheaper fuel cells has been published on Technology Org.
When researchers asked people to tell the stories of how they fell in love, what were the eleven most common factors?
Variables that influence falling in love:
1. Similarity in attitudes, background, personality traits
2. Geographic proximity
3. Desirable characteristics of personality and appearance
4. Reciprocal affection, the fact that the other likes us
5. Satisfying needs
6. Physical and emotional arousal
7. Social influences, norms, and the approval of people in our circle
8. Specific cues in the beloved's voice, eyes, posture, way of moving
9. Readiness for a romantic relationship...
More
The city of Portland, OR will empty a 38-million gallon reservoir after a teenager allegedly urinated in it, according to the Associated Press. It's the second time in three years that Portland is flushing its Mount Tabor reservoir after a urine-related incident.
The reservoir is open-air and sits exposed to all of nature, leading many parties to question how necessary a draining would be, or how polluted 38 million gallons of water can really be by a single man's urine.
David Shaff, Portland's water bureau administrator, reserves a special disgust specifically for human urine. In 2011, when Shaff drained the reservoir following a urination, he reasoned to the Portland Mercury, "Do you want to be drinking someone's pee?… There's probably no regulation that says I have to be doing it but, again, who wants to be drinking pee?" This time around, Shaff wrote in a statement, "Our customers have an expectation that their water is not deliberately contaminated."
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Inexpensive computers, cell phones and other systems that substitute flexible plastic for silicon chips may be one step closer to reality, thanks to research published on April 16 in the journal Nature Communications. The paper describes a new proposal by University of Iowa researchers and their colleagues at New York University for overcoming a major obstacle to the development of such plastic devices—the large amount of energy required to read stored information. Although it is relatively cheap and easy to encode information in light for fiber optic transmission, storing information is most efficiently done using magnetism, which ensures information will survive for years without any additional power. “So a critical issue is how to convert information from one type to another,” says Michael Flatté, professor of physics and astronomy in the College of Liberal Arts and Sciences (CLAS) and director of the UI Optical Science and Technology Center. “Although it does not cost a lot of energy to convert one to the other in ordinary, silicon-chip-based computers, the energy cost is very high for flexible, plastic computing devices that are hoped to be used for inexpensive “throwaway” information processors. “Here we show an efficient means of converting information encoded in magnetic storage to
The post Information storage for the next generation of plastic computers has been published on Technology Org.
Yahia Makableh demonstrates how a small array of 9-millimeter, gallium-arsenide solar cells can provide energy for small devices. Engineering researchers at the University of Arkansas have achieved the highest efficiency ever in a 9 millimeter-squared solar cell made of gallium arsenide. After coating the cufflink-sized cells with a thin layer of zinc oxide, the research team reached a conversion efficiency of 14 percent. A small array of these cells – as few as nine to 12 – generate enough energy for small light-emitting diodes and other devices. But surface modification can be scaled up, and the cells can be packaged in large arrays of panels to power large devices such as homes, satellites, or even spacecraft. The research team, led by Omar Manasreh, professor of electrical engineering, published its findings in Applied Physics Letters and the April 2014 issue of Solar Energy Materials and Solar Cells. An alternative to silicon, gallium arsenide is a semiconductor used to manufacture integrated circuits, light-emitting diodes and solar cells. The surface modification, achieved through a chemical synthesis of thin films, nanostructures and nanoparticles, suppressed the sun’s reflection so the cell could absorb more light. But even without the surface coating, the researchers were able to achieve 9-percent efficiency
The post Researchers achieve higher solar-cell efficiency with zinc-oxide coating has been published on Technology Org.
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Methylammonium lead iodide perovskite In the past few years, perovskite solar cells have made large leaps forward in efficiency, recently achieving energy conversion with up to 16 percent efficiency. These simple and promising devices are easy enough to make and are made up of earth abundant materials, but little work has been done to explore their atomic makeup. Researchers at Brookhaven National Laboratory and Columbia University used high-energy x-rays at the National Synchrotron Light Source (NSLS) to characterize the structure of methylammonium lead iodide (MAPbI3) in titanium oxide – the active material in high-performance perovskite solar cells. Their results are reported in a paper published online in Nano Letters on November 22, 2013, Photoluminescent properties of these materials are thought to depend sensitively on the degree of structural order and defects. To characterize the structure, the researchers used beamline X17A at NSLS to study samples of the MAPbI3. Atomic pair distribution function analysis of x-ray diffraction data revealed that 30 percent of the material forms a tetragonal perovskite phase, while 70 percent exists in a disordered state. The presence of disordered material correlates with strong changes in the photoluminescence and absorbance spectra. Read more at: Phys.org
The post Disorder on the nanoscale may be responsible for solar-cell efficiency has been published on Technology Org.
Ever stop to consider why lotus plant leaves always look clean? The hydrophobic – water repelling – characteristic of the leaf, termed the “Lotus effect,” helps the plant survive in muddy swamps, repelling dirt and producing beautiful flowers. Of late, engineers have been paying more and more attention to nature’s efficiencies, such as the Lotus effect, and studying its behavior in order to make advances in technology. As one example, learning more about swarming schools of fish is aiding in the development of unmanned underwater vehicles. Other researchers are observing the extraordinary navigational abilities of bats that might lead to new ways to reconfigure aviation highways in the skies. Ranga Pitchumani , professor of mechanical engineering at Virginia Tech and currently on an invitational assignment as the chief scientist and director of the Concentrating Solar Power and Systems Integration programs of the U.S. Department of Energy’s SunShot Initiative, would like to see more efficiencies and clever designs in technology. His work reflects this philosophy. His recent development of a type of coating for materials that has little to no affinity for water emulates the Lotus effect. Commonplace material coatings are as simple as paints and varnishes. More sophisticated coatings might be used
The post New material coating technology mimics nature’s lotus effect has been published on Technology Org.
An artist’s rendering of the thickness-driven, metal-insulator transition in sub-nanometer films of a lanthanum nickelate. Nickel atoms are shown in gold, oxygen atoms in white, and lanthanum atoms in red, and metallicity is achieved in going from two to three atomic layers. Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance and other exotic properties. These possibilities have scientists excited to understand everything about these materials, and to find new ways to control their properties at the most fundamental levels. Researchers from Cornell and Brookhaven National Laboratory have shown how to switch a particular transition metal oxide, a lanthanum nickelate (LaNiO3), from a metal to an insulator by making the material less than a nanometer thick. The team, which published its findings online April 6 in Nature Nanotechnology (to appear in the journal’s May issue), includes lead researcher Kyle Shen, associate professor of physics; first author Phil King, a recent Kavli postdoctoral fellow at Cornell now on the faculty at the University of St. Andrews; Darrell Schlom, the Herbert Fisk Johnson Professor of Industrial Chemistry; and co-authors Haofei Wei,
The post ‘Exotic’ material is like a switch when super thin has been published on Technology Org.
Equations are the lifeblood of mathematics, science, and technology. Without them, our world would not exist in its present form. However, equations have a reputation for being scary: Stephen Hawking's publishers told him that every equation would halve the sales of A Brief History of Time. [In Pursuit of the Unknown: 17 Equations That Changed the World]
This captures our aversion to equations well. Yet, as mathematician Ian Stewart argues in his book In Pursuit of the Unknown: 17 Equations That Changed the World, "[e]quations are too important to be hidden away."
Equations are a vital part...
MoreTrillions of microbes live in and on our body. We don’t yet fully understand how these microbial ecosystems develop or the full extent to which they influence our health. Some provide essential nutrients, while others cause disease. A new study now provides some unexpected influences on the contents of these communities, as scientists have found that life history, including level of education, can affect the sorts of microbes that flourish. They think this information could help in the diagnosis and treatment of disease.
A healthy human provides a home for about 100 trillion bacteria and other microbes. These microbes are known as the microbiome, and they normally live on the body in communities, with specialized populations on different organs.
Evolution has assured that both humans and bacteria benefit from this relationship. In exchange for somewhere to live, bacteria protect their hosts from harmful pathogens. Past analysis of the gut microbiome has shown that when this beneficial relationship breaks down, it can lead to illnesses such as Crohn’s disease, a chronic digestive disorder.
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