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.
When it comes to imaging, every single photon counts if there is barely any available light. This is the point where the latest technologies often reach their limits. Researchers have now developed a single photon avalanche photodiode that can read individual photons in just a few picoseconds. The speed allows the image sensor to capture high quality images with very low light levels.
New tests of nanostructured material developed by scientists at Rice University and Massachusetts Institute of Technology could lead to better armor against everything from gunfire to micrometeorites. The key, they found, was to use composites made of two or more materials whose stiffness and flexibility are structured in very specific ways—such as in alternating layers just a few nanometers thick.
Oxide catalysts play an integral role in many chemical transformations. Greener, more efficient chemical processes would benefit greatly from solid oxide catalysts that are choosier about their reactants, but achieving this has prove a challenge. Now, a team of researchers have developed a straightforward and generalizable process for making reactant-selective oxide catalysts by encapsulating the particles in a sieve-like film that blocks unwanted reactants.
Stanford University scientists have built the first solar cell made entirely of carbon, a promising alternative to the expensive materials used in photovoltaic devices today. Unlike rigid silicon solar panels that adorn many rooftops, Stanford's thin film prototype is made of carbon materials that can be coated from solution.
By combining ion processing and nanolithography, scientists from Aalto University in Finland and the University of Washington have managed to create complex 3D structures at nanoscale. The breakthrough was made while studying the irregular folding of metallic thin films after they were processed by reactive ion etching. After determining the cause, the researchers realized they could control the bending activity with an ion beam.
In Harvard University's Pierce Hall, the surface of a small germanium-coated gold sheet shines vividly in crimson. A centimeter to the right, where the same metallic coating is literally only about 20 atoms thicker, the surface is a dark blue, almost black. The colors from the logo of the Harvard School of Engineering and Applied Sciences, where researchers have demonstrated a new way to customize the color of metal surfaces by exploiting an overlooked optical phenomenon.