There is high interest in methods to produce 2D crystals by exfoliating materials with layered structures, but certain ions or solvents can infiltrate materials with layered structures, forcing exfoliation spontaneously and complicating efforts to build practical materials. While working to develop these procedures, researchers in Japan have reported an unusual phenomenon that layered materials undergo drastic swelling without breaking into separate 2D crystal layers.
Scientists at the U.S. Naval Research Laboratory have fabricated a vapor sensor using a single monolayer of molybdenum disulfide (MoS2) on a silicon dioxide wafer. They show that it functions effectively as a chemical vapor sensor, exhibiting highly selective reactivity to a range of analytes, and providing sensitive transduction of transient surface physisorption events to the conductance of the monolayer channel.
Imagine if you could drink a glass of water just by inserting a solid wire into it and sucking on it as though it were a soda straw. It turns out that if you were tiny enough, that method would work just fine—and wouldn’t even require the suction to start. New research has demonstrated, for the first time, that when inserted into a pool of liquid, nanowires naturally draw the liquid upward in a thin film that coats the surface of the wire.
According to recent research at Rice University, vanadium oxide and graphene may be a key new set of materials for improving lithium-ion storage. Ribbons created at Rice from these two materials 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. Initial capacity remains at 90% or more after more than 1,000 cycles.
Semiconducting polymers are an unruly bunch, but University of Michigan engineers have developed a new method for getting them in line that could pave the way for cheaper, greener, "paint-on" plastic electronics.
A current optical-sensing technology can launch and guide a single light wave, called a surface-plasmon-polariton (SPP) wave, that travels along the flat interface of the sample to be analyzed. However, only one wave can be used, allowing the analysis of just one substance. Researchers at Penn State University have designed a thin film that can create additional channels for the SPP waves.
For years, researchers have developed thin films of bismuth telluride, which converts heat into electricity or electricity to cooling, on top of gallium arsenide to create cooling devices for electronics. But it was not clear how this could be done because the atomic structures do not appear to be compatible. Researchers from North Carolina State University and RTI International have now solved the mystery.
A multi-university research team has used a new spectroscopic method—energy-momentum spectroscopy—to gain a key insight into how light is emitted from layered nanomaterials and other thin films. The technique lets researchers understand the source and orientation of light in light-emitting thin films and could lead to better LEDs, solar cells, and other devices that use layered nanomaterials.
Until recently, there has been no systematic way of evaluating how different anti-fog coatings perform under real-world conditions. A team of MIT researchers has developed such a testing method, and used it to find a coating that outperforms others not only in preventing foggy buildups, but also in maintaining good optical properties without distortion.
The salinity difference between freshwater and saltwater could be a source of renewable energy. However, power yields from existing techniques are not high enough to make them viable. A team led by physicists in France has discovered a new means of harnessing this energy. Their method of osmotic flow through boron nitride nanotubes generates electric currents with 1,000 times the efficiency of any previous system.
Northwestern University’s Yonggang Huang and the University of Illinois’ John A. Rogers are the first to demonstrate a stretchable lithium-ion battery—a flexible device capable of powering their innovative stretchable electronics. Their battery continues to work—powering a commercial light-emitting diode (LED)—even when stretched, folded, twisted and mounted on a human elbow. The battery can work for eight to nine hours before it needs recharging, which can be done wirelessly.
New research by Yale University scientists helps pave the way for the next generation of solar cells, a renewable energy technology that directly converts solar energy into electricity. In a pair of recent papers, Yale engineers report a novel and cost-effective way to improve the efficiency of crystalline silicon solar cells through the application of thin, smooth carbon nanotube films.
Recent research shows that a newly discovered class of materials, called layered oxide heterostructures, could have optimal electrical characteristics. A research team at the Vienna University of Technology, together with colleagues from the United States and Germany, has now shown that these heterostructures can be used to create a new kind of extremely efficient ultra-thin solar cells.
Like turning coal to diamond, adding pressure to an electrical material enhances its properties. Now, University of Illinois at Urbana-Champaign researchers have devised a method of making ferroelectric thin films with twice the strain, resulting in exceptional performance.
Researchers have tried for decades to replicate the effects of transistors in transition metal oxides by using a voltage to convert the material from an insulator to a metal, but the induced change only occurs within a few atomic layers of the surface. Recently, however, scientists in Japan have discovered that applying a voltage to a vanadium dioxide film several tens of nanometers thick converts the entire film from an insulator to a metal.
Found in flat screens, solar modules, or in new organic light-emitting diode (LED) displays, transparent electrodes have become ubiquitous. But since raw materials like indium are becoming more and more costly, researchers have begun to look elsewhere for alternatives. A new review article sheds some light on the different advantages and disadvantages of established and new materials for use in these kinds of contact electrodes.
Physicists have recently demonstrated that the application of a very strong alternating electric field to thin liquid crystal cells leads to a new distinct nonlinear dynamic effect in the response of the cells. Researchers were able to explain this result through spatio-temporal chaos theory. The finding has implications for the operation of liquid crystal devices because their operation depends on electro-optic switch phenomena.
Researchers in Germany have developed a new generation of image sensors that are more sensitive to light than the conventional silicon versions. Simple and cheap to produce, they consist of electrically conductive plastics which are sprayed onto the sensor surface in an ultra-thin layer. The chemical composition of the polymer spray coating can be altered so that even the invisible range of the light spectrum can be captured.
Researchers at the Aalto University School of Chemical Technology have applied atomic layer deposition (ALD) technique to the synthesis of thermoelectric materials. Converting waste energy into electricity, these materials are a promising means of producing energy cost-effectively and without carbon dioxide emissions in the future.
In an advance toward stain-proof, spill-proof clothing, protective garments and other products that shrug off virtually every liquid—from blood and ketchup to concentrated acids—scientists are reporting development of new "superomniphobic" surfaces. These new surfaces display extreme repellency to two families of liquids: Newtonian and non-Newtonian.
It may be possible soon to charge cell phones, change the tint on windows, or power small toys with peel-and-stick versions of solar cells. A partnership between Stanford University and the National Renewable Energy Laboratory aims to produce water-assisted transfer printing technologies that support thin-film solar cell production.
Massachusetts Institute of Technology engineers have created a new polymer film that can generate electricity by drawing on a ubiquitous source: water vapor. The new material changes its shape after absorbing tiny amounts of evaporated water, allowing it to repeatedly curl up and down. Harnessing this continuous motion could drive robotic limbs or generate enough electricity to power micro- and nanoelectronic devices, such as environmental sensors.
Growth of new materials is the cornerstone of materials science. At the same time, the energy crisis has brought the spotlight on synthesis and growth of materials for clean energy technologies. However, researchers in these areas do simply grow materials—they assemble the atoms and molecules that form so-called thin films on various substrates, a complex, time-consuming process. Now, a team of engineers is using microwave energy to assemble atoms into thin films and grow them directly onto a substrate at low temperatures.
A research group at NIST has developed a relatively simple, fast, and effective method of depositing uniform, ultrathin layers of platinum atoms on a surface. The new process exploits an unexpected feature of electrodeposition of platinum—if you drive the reaction much more strongly than usual, a new reaction steps in to shuts down the metal deposition process, allowing an unprecedented level of control of the film thickness.
A sensor invented by Tufts University bioengineers, when attached temporarily to a tooth, could one day help dentists fine-tune treatments for patients with chronic periodontitis, for example, or even provide a window on a patient’s overall health. The thin foil-like sensor is built from gold, silk, and graphite, has a built-in antenna to receive power and signals, and is applied directly to a tooth.