Researchers at North Carolina State University have developed a new technique for creating high-quality semiconductor thin films at the atomic scale – meaning the films are only one atom thick. The technique can be used to create these thin films on a large scale, sufficient to coat wafers that are two inches wide, or larger.

“This could be used to scale current semiconductor technologies down to the atomic scale – lasers, light-emitting diodes (LEDs), computer chips, anything,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and senior author of a paper on the work. “People have been talking about this concept for a long time, but it wasn’t possible. With this discovery, I think it’s possible.”
“The key to our success is the development of a new growth mechanism, a self-limiting growth,” Cao says. The researchers can precisely control the thickness of the MoS2 layer by controlling the partial pressure and vapor pressure in the furnace. Partial pressure is the tendency of atoms or molecules suspended in the air to condense into a solid and settle onto the substrate. Vapor pressure is the tendency of solid atoms or molecules on the substrate to vaporize and rise into the air.

Source: http://news.ncsu.edu/

Imagine a bendable tablet computer or an electronic newspaper that could fold to fit in a pocket. The technology for these devices may not be so far off. Northwestern University researchers have recently developed a graphene-based ink that is highly conductive and tolerant to bending, and they have used it to inkjet-print graphene patterns that could be used for extremely detailed, conductive electrodes.
The resulting patterns are 250 times more conductive than previous attempts to print graphene-based electronic patterns and could be a step toward low-cost, foldable electronics.

“Graphene has a unique combination of properties that is ideal for next-generation electronics, including high electrical conductivity, mechanical flexibility, and chemical stability,” said Mark Hersam, professor of materials science and engineering at Northwestern’s McCormick School of Engineering and Applied Science. “By formulating an inkjet-printable ink based on graphene, we now have an inexpensive and scalable path for exploiting these properties in real-world technologies.”
A paper describing the research, has been published in the Journal of Physical Chemistry Letters.
Source: http://www.mccormick.northwestern.edu/

Northwestern University scientists have struck gold in the laboratory. They have discovered an inexpensive and environmentally benign method that uses simple cornstarch – instead of cyanide — to isolate gold from raw materials in a selective manner. This green method extracts gold from crude sources and leaves behind other metals that are often found mixed together with the crude gold. The new process also can be used to extract gold from consumer electronic waste. Current methods for gold recovery involve the use of highly poisonous cyanides, often leading to contamination of the environment. Nearly all gold-mining companies use this toxic gold leaching process to sequester the precious metal.

A modern day gold rush! A new method developed at Northwestern bypasses the use of toxic cyanide for gold purification by using an eco-friendly sugar (cyclodextrin) derived from starch
“The elimination of cyanide from the gold industry is of the utmost importance environmentally,” said Sir Fraser Stoddart, the Board of Trustees Professor of Chemistry in the Weinberg College of Arts and Sciences. “We have replaced nasty reagents with a cheap, biologically friendly material derived from starch.”
Source: http://www.northwestern.edu/

Researchers from the Georgia Institute of Technology have fabricated arrays of piezotronic transistors capable of converting mechanical motion directly into electronic controlling signals. The arrays could help give robots a more adaptive sense of touch. Mimicking the sense of touch electronically has been challenging, and is now done by measuring changes in resistance prompted by mechanical touch. The devices developed By Georgia Tech scientists rely on a different physical phenomenon – tiny polarization charges formed when piezoelectric materials such as zinc oxide are moved or placed under strain. In the piezotronic transistors, the piezoelectric charges control the flow of current through the wires just as gate voltages do in conventional three-terminal transistors.

“Any mechanical motion, such as the movement of arms or the fingers of a robot, could be translated to control signals,” explained Zhong Lin Wang, a Regents’ professor and Hightower Chair in the School of Materials Science and Engineering at the Georgia Institute of Technology. “This could make artificial skin smarter and more like the human skin. It would allow the skin to feel activity on the surface.”
Source: http://www.gatech.edu/

Scientists at Princeton University used off-the-shelf printing tools to create a functional ear that can “hear” radio frequencies far beyond the range of normal human capability. The researchers’ primary purpose was to explore an efficient and versatile means to merge electronics with tissue. The scientists used 3D printing of cells and nanoparticles followed by cell culture to combine a small coil antenna with cartilage, creating what they term a bionic ear.

“In general, there are mechanical and thermal challenges with interfacing electronic materials with biological materials,” said Michael McAlpine, an assistant professor of mechanical and aerospace engineering at Princeton and the lead researcher. “Previously, researchers have suggested some strategies to tailor the electronics so that this merger is less awkward. That typically happens between a 2D sheet of electronics and a surface of the tissue. However, our work suggests a new approach — to build and grow the biology up with the electronics synergistically and in a 3D interwoven format.”

Source: http://www.eurekalert.org/

Researchers from Purdue University have found a way to see synthetic nanostructures and molecules using a new type of super-resolution optical microscopy that does not require fluorescent dyes, representing a practical tool for biomedical and nanotechnology research.

A new type of super-resolution optical microscopy takes a high-resolution image (at right) of graphite “nanoplatelets” about 100 nanometers wide. The imaging system, called saturated transient absorption microscopy, or STAM, uses a trio of laser beams and represents a practical tool for biomedical and nanotechnology research.

“Super-resolution optical microscopy has opened a new window into the nanoscopic world,” said Ji-Xin Cheng, an associate professor of biomedical engineering and chemistry at Purdue University.”The diffraction limit represents the fundamental limit of optical imaging resolution,” Cheng said. “Stefan Hell at the Max Planck Institute and others have developed super-resolution imaging methods that require fluorescent labels. Here, we demonstrate a new scheme for breaking the diffraction limit in optical imaging of non-fluorescent species. Because it is label-free, the signal is directly from the object so that we can learn more about the nanostructure.”

Source: http://www.purdue.edu/

Researchers at the U.S. Department of Energy’s Brookhaven National Laboratory describe details of a low-cost, stable, effective catalyst that could replace costly platinum in the production of hydrogen. The catalyst, made from renewable soybeans and abundant molybdenum metal, produces hydrogen in an environmentally friendly, cost-effective manner, potentially increasing the use of this clean energy source.
Their ultimate goal is to find ways to use solar energy — either directly or via electricity generated by solar cells — to convert the end products of hydrocarbon combustion, water and carbon dioxide, back into a carbon-based fuel. Dubbed “artificial photosynthesis,” this process mimics how plants convert those same ingredients to energy in the form of sugars. One key step is splitting water, or water electrolysis.

“By splitting liquid water (H2O) into hydrogen and oxygen, the hydrogen can be regenerated as a gas (H2) and used directly as fuel,” explains Etsuko Sasaki, member of the Broohaven team.
“A very promising route to making a carbon-containing fuel is to hydrogenate carbon dioxide (or carbon monoxide) using solar-produced hydrogen,” adds Fujita, who leads the artificial photosynthesis group in the Brookhaven Chemistry Department.

Source: http://www.bnl.gov/

University of Nebraska-Lincoln materials engineers have developed a structural nanofiber that is both strong and tough, a discovery that could transform everything from airplanes and bridges to body armor and bicycles. Their findings are featured on the cover of this week’s April issue of the American Chemical Society’s journal, ACS Nano.

“Whatever is made of composites can benefit from our nanofibers,” said the team’s leader, Yuris Dzenis, McBroom Professor of Mechanical and Materials Engineering and a member of UNL‘s Nebraska Center for Materials and Nanoscience. “Our discovery adds a new material class to the very select current family of materials with demonstrated simultaneously high strength and toughness.”
Source: http://newsroom.unl.edu/

Researchers at the University of Exeter – United Kingdom – have developed a new photoelectric device that is both flexible and transparent. The device, described in a paper in the journal ACS Nano, converts light into electrical signals by exploiting the unique properties of the recently discovered materials graphene and graphExeter. GraphExeter is the best known room temperature transparent conductor and graphene is the thinnest conductive material. At just a few atoms thick, the newly developed photoelectric device is ultra-lightweight. This, along with the flexibility of its constituent graphene materials, makes it perfect for incorporating into clothing. Such devices could be used to develop photovoltaic textiles enabling clothes to act as solar panels and charge mobile phones while they are being worn.

Saverio Russo, Professor of Physics at the University of Exeter said: “This new flexible and transparent photosensitive device uses graphene and graphExeter to convert light into electrical signals with efficiency comparable to that found in opaque devices based on graphene and metals.
“We are only just starting to explore the interfaces between different materials at very small scales and, as this research shows, we are revealing unique properties that we never knew existed. Who knows what surprises are just around the corner.”

Source: http://www.exeter.ac.uk/

Though they be but little, they are fierce. The most powerful batteries on the planet are only a few millimeters in size, yet they pack such a punch that a driver could use a cellphone powered by these batteries to jump-start a dead car battery – and then recharge the phone in the blink of an eye.
Mechanical science and engineering professor William P. King led a group that developed the most powerful microbatteries ever documented.
Developed by researchers at the University of Illinois at Urbana-Champaign, the new microbatteries out-power even the best supercapacitors and could drive new applications in radio communications and compact electronics.

The graphic illustrates a high power battery technology from the University of Illinois. Ions flow between three-dimensional micro-electrodes in a lithium ion battery.

“Any kind of electronic device is limited by the size of the battery – until now,” King said. “Consider personal medical devices and implants, where the battery is an enormous brick, and it’s connected to itty-bitty electronics and tiny wires. Now the battery is also tiny.”
Now, the researchers are working on integrating their batteries with other electronics components, as well as manufacturability at low cost.

“Now we can think outside of the box,” said James Pikul, a graduate student and first author of the paper. “It’s a new enabling technology. It’s not a progressive improvement over previous technologies; it breaks the normal paradigms of energy sources. It’s allowing us to do different, new things.”

Source: http://news.illinois.edu/

Researchers are developing a new type of semiconductor technology for future computers and electronics based on “two-dimensional nanocrystals” layered in sheets less than a nanometer thick that could replace today’s transistors. New technologies will be needed to allow the semiconductor industry to continue advances in computer performance driven by the ability to create ever-smaller transistors.

“We are going to reach the fundamental limits of silicon-based CMOS technology very soon, and that means novel materials must be found in order to continue scaling,” said Saptarshi Das, who has completed a doctoral degree, working with Joerg Appenzeller, a professor and scientific director of nanoelectronics at Purdue‘s Birck Nanotechnology Center. “I don’t think silicon can be replaced by a single material, but probably different materials will co-exist in a hybrid technology.”

Source: http://www.purdue.edu/

Better integration of photonic and electronic components in nanoscale devices may now become possible, thanks to work by Khuong Phuong Ong and Hong-Son Chu from the A*STAR Institute of High Performance Computing and their co-workers in Singapore and the US. From computer simulations, they have identified that the compound BiFeO3 has the potential to be used to efficiently couple light to electrical charges through light-induced electron oscillations known as plasmons. The researchers propose that this coupling could be activated, controlled and switched off, on demand, by applying an electrical field to an active plasmonic device based on this material. If such a device were realized on a very small footprint it would give scientists a versatile tool for connecting components that manipulate light or electric currents.

Thin poles standing in water barely affect waves rolling past them. Similarly, nanostructured devices typically do not interact with light waves

Many devices used in everyday life — whether they be televisions, mobile phones or barcode scanners — are based on the manipulation of electric currents and light. At the micro- and nano-scales, however, it is typically challenging to integrate electronic components with photonic components. At these small dimensions, the wavelengths of light become long relative to the size of the device. Consequently, the light waves are barely detectable by the device, just as passing waves simply roll past thin poles in a water body (see image).

Source: http://www.research.a-star.edu.sg/research/6656

Professor Dong Rip Kim from Hangyang University – Korea – has succeeded in fabricating peel-and-stick thin film solar cells (TFSCs) with the collaboration of Stanford team led by Professor Xiaolin Zheng. This method makes possible the overcoming of hardships related to working with traditional solar cells, namely the lack of handling, high manufacturing cost, and limited flexibility while maintaining performance. Kim is currently in charge of the Hanyang University Nanotechnology for Energy Conversion Lab. His research interests are solar cells, energy conversion devices using nanomaterials, flexible electronics, nanoelectronics, and nanosensors. Among Kim’s recent publications are “Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates” in the journal of Scientific Reports, “Shrinking and Growing: Grain Boundary Density Reduction for Efficient Polysilicon Thin-Film Solar Cells” in the journal of Nano Letters, and “Thermal Conductivity in Porous Silicon Nanowire Arrays” in the journal of Nanoscale Research Letters.

“I will continue to focus on creating highly efficient but low costing energy conversion devices with nanotechnology,” Kim said. Moreover, his future research will focus on applying his method in other types of solar cells and in other applications.

Source: http://www.hanyang.ac.kr/

More powerful batteries could help electric cars achieve a considerably larger range and thus a breakthrough on the market. Laboratory of Inorganic Chemistry at ETH Zurich and Empa -Switzerland – have now developed a nanomaterial which enables considerably more power to be stored in lithium ion batteries. They provide power not only for electric cars, but also for electric bicycles, smartphones and laptops; nowadays, rechargeable lithium ion batteries are the storage media of choice when it comes to supplying a large amount of energy in a small space and light weight.

Monodisperse tin nanodroplets in an electron microscopic

During the development of the nanomaterial, the issue of the ideal size for the nanocrystals arose, which also carries the challenge of producing uniform crystals. “The trick here was to separate the two basic steps in the formation of the crystals – the formation of as small as a crystal nucleus as possible on the one hand and its subsequent growth on the other,” explains Maksym Kovalenko, head of the research team at ETH Zurich. By influencing the time and temperature of the growth phase, the scientists were able to control the size of the crystals. “We are the first to produce such small tin crystals with such precision,” says the scientist.

Source: http://www.ethlife.ethz.ch/

Scientists at Aalto University, Finland and Fraunhofer ISE, Germany report an efficiency of 18.7% for black silicon solar cells, the highest efficiency reported so far for a black silicon solar cell.
The researchers were able to apply a boron diffusion to create a pn-junction, maintaining the excellent optical properties of the black silicon structure. By applying atomic layer deposited Al203, an effective passivation of the nanostructured surfaces was achieved. The previous efficiency record of 18.2% was held by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) using thermal oxidation as a passivating layer.

“The quantum efficiency measurements reveal that the nanostructured front surface is of a high electrical quality comparable to a pyramidal textured surface”, says Assistant Professor Hele Savin of Aalto University.
Routes for improving the cell efficiency are already identified, and efficiencies clearly above 20% should be within reach.
Source: http://www.aalto.fi/

Researchers at the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) at Trinity College in Dublin – Ireland – are pursuing a new nanomaterial-based approach to neural networks that combines work in nanowires and memristors (2-terminal memory devices based on resistance switching effects). They develop a new computing paradigm that mimics the neural networks of the human brain. Both nanowires and memristors are part of the history of research into neural networks and artificial intelligence (AI). Researchers have been investigating the use of nanowires in building electronic meshes on which nerve tissues can be grown; the mesh, they hope, could link nerve cells with electronics. And almost from the time memristors were first isolated and characterized, researchers have been looking at using them in chips that would lead to artificial intelligence.
Professor John Boland, director of CRANN, and his colleagues will be using the research grant to build on their previous work. They already discovered that when electricity—or other stimuli such as chemicals or light—is applied to a random network of nanowires, it generates a chemical reactions at the junctions where the nanowires cross over each other.

This phenomenon is similar to the way the brain works, in that there are bundles of nerves that cross over one another, forming junctions. Over time, the human brain begins to learn which of these junctions is important and discards the rest.
Source: http://www.tcd.ie/

A team of scientists from Polytechnique Montréal (Canada), Northwestern University (USA), and Max Planck Institute of Microstructure Physics (Germany) led by Professor Oussama Moutanabbir has made a fascinating discovery of a novel process to precisely functionalize nanowires. By using aluminum as a catalyst instead of the canonical gold, the team demonstrated that the growth of nanowires triggers a self-doping process involving the injection of aluminum atoms thus providing an efficient route to dope nanowires without the need of post-growth processing typically used in semiconductor industry. The scientists investigated this phenomenon at the atomistic-level using the emerging technique of highly focused ultraviolet laser-assisted atom-probe tomography to achieve three-dimensional atom-by-atom maps of individual nanowires.

The discovery provides myriad opportunities to create entirely new class of nanoscale devices by precisely tailoring shape and composition of nanowires. The results of their breakthrough will be published in Nature.
Source: http://www.eurekalert.org/

A Stanford team has designed an entirely new form of cooling panel that works even when the sun is shining. Such a panel could vastly improve the daylight cooling of buildings, cars and other structures by radiating sunlight back into the chilly vacuum of space.
In the future we can imagine homes and buildings chilled without air conditioners. Car interiors that don’t heat up in the summer sun. Tapping the frigid expanses of outer space to cool the planet. Science fiction, you say? Well, maybe not any more.

“People usually see space as a source of heat from the sun, but away from the sun outer space is really a cold, cold place,” explained Shanhui Fan, professor of electrical engineering and the paper’s senior author. “We’ve developed a new type of structure that reflects the vast majority of sunlight, while at the same time it sends heat into that coldness, which cools manmade structures even in the day time.”

Source: http://engineering.stanford.edu/

The Rice University lab of materials scientist Pulickel Ajayan determined that Hybrid ribbons of vanadium oxide (VO2) and graphene, is a superior cathode for batteries that could supply both high energy density and significant power density. The ribbons created at Rice are thousands of times thinner than a sheet of paper, yet have potential that far outweighs current materials for their ability to charge and discharge very quickly. Cathodes built into half-cells for testing at Rice fully charged and discharged in 20 seconds and retained more than 90 percent of their initial capacity after more than 1,000 cycles.

“This is the direction battery research is going, not only for something with high energy density but also high power density,” Ajayan said. “It’s somewhere between a battery and a supercapacitor.”
These new Hybrid ribbons could be decisive to build high-power lithium-ion batteries suitable for electric cars.
The research appears online this month in the American Chemical Society journal Nano Letters.
Source: http://news.rice.edu/

Scientists from the Nano-Science Center at the Niels Bohr Institut, Denmark and the Ecole Polytechnique Fédérale de Lausanne, Switzerland, have shown that a single nanowire can concentrate the sunlight up to 15 times of the normal sun light intensity. The results are surprising and the potential for developing a new type of highly efficient solar cells is great.

Due to some unique physical light absorption properties of nanowires, the limit of how much energy we can utilize from the sun’s rays is higher than previous believed. These results demonstrate the great potential of development of nanowire-based solar cells, says PhD Peter Krogstrup on the surprising discovery that is described in the journal Nature Photonics.
Source: http://www.nbi.ku.dk/

A team of IBM researchers working on a U.S. Defense Advanced Research Projects Agency (DARPA)-funded program have found a way to transmit massive amounts of data with unprecedentedly low power consumption. Scientists predict that the supercomputers of the future—so-called “exascale computers“—will enable them to model the global climate, run molecular-level simulations of entire cells, design nanostructures, and more.

“We envision machines reaching the exascale mark around 2020, but a great deal of research must be done to make this possible,” says Jonathan E. Proesel, a research staff member at the IBM T. J. Watson Research Center in Yorktown Heights, N.Y. To reach that mark, researchers must develop a way to quickly move massive amounts of data within the supercomputer while keeping power consumption in check.

Source: http://www.eurekalert.org/

A new x-ray imaging technique yields unprecedented measurements of nanoscale structures. Now, owing to a happy accident and subsequent insight, researchers at the US Department of Energy’s (DOE) Brookhaven National Laboratory have developed a new and strikingly simple x-ray scattering technique—detailed in the February issue of the Journal of Applied Crystallography—to help draw nanomaterials ranging from catalysts to proteins into greater focus.
This rendering shows the high-intensity x-ray beam striking and then traveling through the gray sample material. In this new technique, the x-ray scattering—the blue and white ripples—is considerably less distorted than in other methods, producing superior images with less complex analysis.“During an experiment, we noticed that one of the samples was misaligned,” said physicist Kevin Yager, a coauthor on the new study. “Our x-ray beam was hitting the edge, not the center as is typically desired. But when we saw how clean and undistorted the data was, we immediately realized that this could be a huge advantage in measuring nanostructures.”

Source: http://www.bnl.gov/

A new technique developed by University of Toronto Engineering Professor Ted Sargent and his research group could lead to significantly more efficient solar cells. The solution? Spectrally tuned, solution-processed plasmonic nanoparticles. These particles, the researchers say, provide unprecedented control over light’s propagation and absorption. The new technique developed by Sargent’s group shows a possible 35 per cent increase in the technology’s efficiency in the near-infrared spectral region, says co-author Dr. Susanna Thon. Overall, this could translate to an 11 per cent solar power conversion efficiency increase, she says, making quantum dot photovoltaics even more attractive as an alternative to current solar cell technologies.

“There are two advantages to colloidal quantum dots,” Thon says. “First, they’re much cheaper, so they reduce the cost of electricity generation measured in cost per watt of power. But the main advantage is that by simply changing the size of the quantum dot, you can change its light-absorption spectrum. Changing the size is very easy, and this size-tunability is a property shared by plasmonic materials: by changing the size of the plasmonic particles, we were able to overlap the absorption and scattering spectra of these two key classes of nanomaterials.”

Source: http://media.utoronto.ca/

A researcher from North Carolina State University has developed a technique for creating high-density ceramic materials that requires far lower temperatures than current techniques – and takes less than a second, as opposed to hours. Ceramics are used in a wide variety of technologies, including body armor, fuel cells, spark plugs, nuclear rods and superconductors. At issue is a process known as “sintering,” which is when ceramic powders (such as zirconia) are compressed into a desired shape and exposed to high heat until the powder particles are bound together into a solid, but slightly porous, material. But new research from Dr. Jay Narayan, John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State, may revolutionize the sintering process.

“This technique allows you to achieve ‘theoretical density,’ meaning it eliminates all of the porosity in the material,” Narayan says. “This increases the strength of the ceramic, as well as improving its optical, magnetic and other properties.”
Source: http://news.ncsu.edu/

While the demand for ever-smaller electronic devices has spurred the miniaturization of a variety of technologies, one area has lagged behind in this downsizing revolution: energy-storage units, such as batteries and capacitors. Now, Richard Kaner, a member of the California NanoSystems Institute at UCLA and a professor of chemistry and biochemistry, and Maher El-Kady, a graduate student in Kaner‘s laboratory, may have changed the game.The UCLA researchers have developed a groundbreaking technique that uses a DVD burner to fabricate micro-scale graphene-based supercapacitors — devices that can charge and discharge a hundred to a thousand times faster than standard batteries. These micro-supercapacitors, made from a one-atom–thick layer of graphitic carbon, can be easily manufactured and readily integrated into small devices such as next-generation pacemakers.The new cost-effective fabrication method, described in a study published this week in the journal Nature Communications, holds promise for the mass production of these supercapacitors, which have the potential to transform electronics .

“The integration of energy-storage units with electronic circuits is challenging and often limits the miniaturization of the entire system,” said Kaner,. “This is because the necessary energy-storage components scale down poorly in size and are not well suited to the planar geometries of most integrated fabrication processes.” “Traditional methods for the fabrication of micro-supercapacitors involve labor-intensive lithographic techniques that have proven difficult for building cost-effective devices, thus limiting their commercial application,” El-Kady said. “Instead, we used a consumer-grade LightScribe DVD burner to produce graphene micro-supercapacitors over large areas at a fraction of the cost of traditional devices. Using this technique, we have been able to produce more than 100 micro-supercapacitors on a single disc in less than 30 minutes, using inexpensive materials.”
Source: http://newsroom.ucla.edu/