A bullet fired through a block of wood will slow down. In a similar way, ions are decelerated when they pass through a solid material: the thicker the material, the larger the energy loss will be. However, as recent experiments in Austria have shown, this picture breaks down in ultra-thin target materials, which only consist of a few layers of atoms.
Of late, engineers have been paying more and more attention to nature’s efficiencies, such as the Lotus effect, which describes the way the Lotus plant uses hydrophobic surfaces to survive in muddy swamps. A researcher at Virginia Tech has developed a simpler two-step application process to create a superhydrophobic copper surface that leverages the Lotus effect.
Researchers have produced a stable porous membrane that is thinner than a single nanometer. The membrane consists of two layers of graphene on which have been etched tiny pores of a precisely defined size. Extremely light and breathable, the new material could help enable a new generation of ultra-rapid filters or functional waterproof clothing.
Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides. Researchers from Cornell Univ. 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.
A research group in Japan has developed a new advanced system that combines a super-resolution microscope and a deposition chamber for growing oxide thin films. With this system, they successfully observed for the first time the growing of metal-oxide thin films at an atomic level on the surface of single-crystal strontium titanate.
Researchers in Pennsylvania and Texas have shown the ability to grow high quality, single-layer materials one on top of the other using chemical vapor deposition. This highly scalable technique, often used in the semiconductor industry, can produce materials with unique properties that could be applied to solar cells, ultracapacitors for energy storage, or advanced transistors for energy efficient electronics, among many other applications.
Solid-state dye-sensitized solar cells have shown their potential in achieving high efficiency with a low cost of fabrication. Degradation of these cells shortens lifespan dramatically, however, and the causes of this are not well understood. After a detailed analysis, researchers in Okinawa have determined which material in the cells was degrading, and why.
New research on perovskite-based solar cells pioneered in the U.K. suggests that they can double up as a laser as well as photovoltaic device. By sandwiching a thin layer of the lead halide perovskite between two mirrors, the Univ. of Cambridge team produced an optically driven laser which proves these cells “show very efficient luminescence”, with up to 70% of absorbed light re-emitted.
A research team led by SLAC National Accelerator Laboratory scientists has uncovered a potential new route to produce thin diamond films for a variety of industrial applications, from cutting tools to electronic devices to electrochemical sensors. The scientists added a few layers of graphene to a metal support and exposed the topmost layer to hydrogen.
Until now, it has been hard to couple light generation into layered semiconductor systems. Scientists in Austria have recently solved this problem using metamaterials, which are able to manipulate light in the terahertz range due to their special microscopic structure. This represents the first combination of metamaterials and quantum cascade structures.
Because of their unique qualities, thermoelectric materials can convert waste heat into electricity. Researchers in the Netherlands have managed to significantly improve the efficiency of a common thermoelectric material by adjusting the fabrication conditions. The material may eventually be used to, for example, put the heat issued from a factory chimney or car exhaust pipe to good use.
In what was almost a chance discovery, researchers in Singapore have developed a solar cell material which can emit light in addition to converting light to electricity. This solar cell is developed from perovskite, a promising material that could hold the key to creating high-efficiency, inexpensive solar cells. The new cells not only glow when electricity passes through them, they can also be customized to emit different colours.
Researchers in the U.K. have developed a new antibacterial material which has potential for cutting hospital acquired infections. The combination of two simple dyes with nanoscopic particles of gold is deadly to bacteria when activated by light, even under modest indoor lighting. And in a first for this type of substance, it also shows impressive antibacterial properties in total darkness.
Imagine a computer so efficient that it can recycle its own waste heat to produce electricity. While such an idea may seem far-fetched today, significant progress has already been made to realize these devices. Researchers at the Univ. of Utah have fabricated spintronics-based thin film devices which do just that, converting even minute waste heat into useful electricity.
Researchers in California have used a beam of intense ultraviolet light to look deep into the electronic structure of a material made of alternating layers of graphene and calcium. While it's been known for nearly a decade that this combined material is superconducting, the new study offers the first compelling evidence that the graphene layers are instrumental in this process. The finding could lead to super-efficient nanoelectronics.
Researchers from North Carolina State Univ. have found a way to reduce the coercivity of nickel-ferrite (NFO) thin films by as much as 80% by patterning the surface of the material, opening the door to more energy efficient high-frequency electronics, such as sensors, microwave devices and antennas.
Researchers have discovered that creating a graphene-copper-graphene “sandwich” strongly enhances the heat conducting properties of copper, a discovery that could further help in the downscaling of electronics.
Will one-atom-thick layers of molybdenum disulfide, a compound that occurs naturally in rocks, prove to be better than graphene for electronic applications? Recent research into phenomena occurring in the crystal network of this material show signs that might prove to be the case. But physicists in Poland have shown that the nature of the phenomena occurring in layered materials are still ill-understood.
Thin films of spin ice have been shown to demonstrate surprising properties which could help in the development of applications of magnetricity, the magnetic equivalent of electricity. Researchers based at the London Centre for Nanotechnology, in collaboration with scientists from Oxford and Cambridge, found that, against expectations, the Third Law of Thermodynamics could be restored in thin films of the magnetic material spin ice.
Organic solar cells are a compelling thin-film photovoltaic technology in part because of their compatibility with flexible substrates and tunable absorption window. Belgium-based chipmaker imec has set a new conversion efficiency record of 8.4% for this type of cell by developing fullerene-free acceptor materials and a new multilayer semiconductor device structure.
Graphene is not the only ultrathin material that exhibits special electronic properties. Ultrathin layers made of tungsten and selenium have recently been created in Austria that show a high internal efficiency when used to gather sunlight. More than 95% of light passes straight through, but a tenth of what is stopped is converted to electricity.
Experts from the Univ. of Buffalo (UB), helped by colleagues from two Chinese universities, have developed an optical "nanocavity" that could help increase the amount of light absorbed by ultrathin semiconductors. The advancement could lead to the creation of more powerful photovoltaic cells and improvements in video cameras and even hydrogen fuel, as the technology could aid the splitting of water using energy from light.
The huge surface area and strong interactions between graphene layers causes facile “stacking” behavior that dramatically reduces available surface area, inhibiting graphene electronic properties. Researchers have tried to prevent this with carbon black, but this also carries undesirable property changes. By introducing protuberances on graphene during synthesis, researchers in China have found a solution to the stacking problem.
A team of researchers has developed a material that could help prevent blood clots associated with catheters, heart valves, vascular grafts and other implanted biomedical devices. Blood clots at or near implanted devices are thought to occur when the flow of nitric oxide, a naturally occurring clot-preventing agent generated in the blood vessels, is cut off. When this occurs, the devices can fail.
Ultraviolet light (UV) has not only harmful effects on molecules and biological tissue like human skin but it also can impair the performance of organic solar cells upon long-term exposure. Researchers in Germany have now developed a so-called plasmonic metamaterial which is compatible with solar technology and completely absorbs UV light despite being only 20 nm thin.