The phase-out of traditional incandescent bulbs in the U.S. and elsewhere, as well as a growing interest in energy efficiency, has given LED lighting a sales boost. That trend could be short-lived as key materials known as rare earth elements become more expensive. Scientists at Rutgers Univ., however, have now designed new materials for making household LED bulbs without using these ingredients.
Researchers have developed a new method for harvesting the energy carried by particles known as “dark” spin-triplet excitons with close to 100% efficiency, clearing the way for hybrid solar cells which could far surpass current efficiency limits. To date, this type of energy transfer had only been shown for “bright” spin-singlet excitons.
Researchers at NIST and the Univ. of Michigan have demonstrated a technique based on the quantum properties of atoms that directly links measurements of electric field strength to the International System of Units. The new method could improve the sensitivity, precision and ease of tests and calibrations of antennas, sensors, and biomedical and nano-electronic systems and facilitate the design of novel devices.
It’s a well-known phenomenon in electronics: Shining light on a semiconductor, such as the silicon used in computer chips and solar cells, will make it more conductive. But now researchers have discovered that in a special semiconductor, light can have the opposite effect, making the material less conductive instead. This new mechanism of photoconduction could lead to next-generation excitonic devices.
Conventional silicon solar cells could have an inexpensive competitor in the near future. Researchers in Europe have examined the working principle of a cell where an organic-inorganic perovskite compound acts as a light absorber. The scientists observed that charge carriers accumulate in a layer in these photovoltaic elements. If this jam can be dissolved, the already considerable efficiency of these solar cells could be further improved.
Arrays of tiny conical tips that eject ionized materials are being made at the Massachusetts Institute of Technology. The technology, which harnesses electrostatic forces, has a range of promising applications, such as spinning out nanofibers for use in “smart” textiles or propulsion systems for fist-sized “nanosatellites.” The latest prototype array that generates 10 times the ion current per emitter that previous arrays did.
The world’s first “solar battery”, invented by researchers at Ohio State Univ., is a battery and a solar cell combined into one hybrid device. Key to the innovation is a mesh solar panel, which allows air to enter the battery, and a special process for transferring electrons between the solar panel and the battery electrode. Inside the device, light and oxygen enable different parts of the chemical reactions that charge the battery.
Nanostructures of virtually any possible shape can now be made using a combination of techniques developed to exploit the unique properties of so-called perovskites. The group based in the Netherlands, developed a pulsed laser deposition technique to create patterns in ultra thin layers, one atomic layer at a time. The perovskites’ crystal structure is undamaged by this soft lithography technique, maintaining electrical conductivity.
Drawn relentlessly by their electrical charges, lithium ions in a battery surge from anode to cathode and back again. Yet, no one really understands what goes on at the atomic scale as lithium ion batteries are used and recharged. Using transmission electron microscopy, researchers are now glimpsing what can happen to anodes as lithium ions work their way into them. The “atomic shuffling” these ions perform leads to rapid anode failure.
Thermal considerations are rapidly becoming one of the most serious design constraints in microelectronics, especially on submicron scale lengths. A study by researchers from the Univ. of Illinois at Urbana-Champaign has shown that standard thermal models will lead to the wrong answer in a 3-D heat-transfer problem if the dimensions of the heating element are on the order of one micron or smaller.
Michael Grätzel’s laboratory in Switzerland is producing hydrogen fuel from sunlight and water. By combining a pair of solar cells made with a mineral called perovskite and low cost electrodes, scientists have obtained a 12.3% conversion efficiency from solar energy to hydrogen, a record using earth-abundant materials as opposed to rare metals.
In a rare case of having their cake and eating it too, scientists from NIST and other institutions have developed a toolset that allows them to explore the complex interior of tiny, multi-layered batteries they devised. It provides insight into the batteries’ performance without destroying them, which results in both a useful probe for scientists and a potential power source for micromachines.
Researchers from the Univ. of Texas at Dallas have created technology that could be the first step toward wearable computers with self-contained power sources or, more immediately, a smartphone that doesn’t die after a few hours of heavy use. This technology taps into the power of a single electron to control energy consumption inside transistors, which are at the core of most modern electronic systems.
Blue organic light-emitting diodes (OLEDs) are one of a trio of colors used in OLED displays such as smartphone screens and high-end TVs. In a step that could lead to longer battery life in smartphones and lower power consumption for large-screen televisions, researchers at the Univ. of Michigan have extended the lifetime of blue organic light emitting diodes by a factor of 10.
Princeton Univ. researchers have developed a new method to increase the power and clarity of light-emitting diodes (LEDs). Using a new nanoscale structure made from flexible carbon-based sheet, the researchers increased the brightness and efficiency of LEDs made of organic materials by 57%.
A common complaints about solar power is that solar panels are still too expensive. Efforts at making them more efficient or longer-lasting have been limited. A new method developed in Okinawa could solve the expense problem: A hybrid form of deposition is being used to create perovskite solar cells from a mixture of inexpensive organic and inorganic raw materials, eliminating the need for expensive crystallized silicon.
An international team of physicists has shown that information stored in the nuclear spins of hydrogen isotopes in an organic light-emitting diode (LED) or organic LED can be read out by measuring the electrical current through the device. Unlike previous schemes that only work at ultracold temperatures, this is the first to operate at room temperature, and could be used to create extremely dense and highly energy-efficient memory devices.
Donald Sadoway and his colleagues at the Massachusetts Institute of Technology have already started a company to produce electrical-grid-scale liquid batteries, whose layers of molten material automatically separate due to their differing densities. But a newly developed formula substitutes different metals for the molten layers. The new formula allows the battery to work at a much lower temperature.
A collaboration between scientists in the Univ. of Chicago’s chemistry department, the Institute for Molecular Engineering and Argonne National Laboratory has produced the highest-ever recorded efficiency for solar cells made of two types of polymers and fulllerene. Researchers identified a new polymer that improved the efficiency of solar cells and also determined the method by which the polymer improved the cells’ efficiency.
For decades, the power conversion efficiency of organic solar cells was hampered by the drawbacks of commonly used metal electrodes, including their instability and susceptibility to oxidation. Now for the first time, researchers at the Univ. of Massachusetts Amherst have developed a more efficient, easily processable and lightweight solar cell that can use virtually any metal for the electrode, effectively breaking the “electrode barrier.”
Combining materials that exhibit magnetic and ferroelectric properties could be a boon for electronics designs, revolutionizing logic circuits and jumpstarting spintronics. This task has proven difficult until a recently developed inorganic synthesis technique, created by chemists at The City College of New York, produced a new complex oxide that demonstrate both properties.
Typically a highly conductive material, graphene becomes a semiconductor when prepared as an ultra-narrow ribbon. Recent research has now developed a new method to selectively dope graphene molecules with nitrogen atoms. By seamlessly stringing together doped and undoped graphene pieces, ”heterojunctions” are formed in the nanoribbons, allowing electric current to flow in only one direction when voltage is applied.
A flexible display incorporating graphene in its pixels’ electronics has been successfully demonstrated by the Cambridge Graphene Centre and Plastic Logic. The new prototype is an active matrix electrophoretic display, similar to the screens used in today’s e-readers, except it is made of flexible plastic instead of glass. This advance marks the first time graphene has been used in a transistor-based flexible device.
A team of U.S. and Swiss researchers have built a new basic model circuit consisting of a silver nanowire and a single-layer flake of molybdenum disulfide. This new combination of materials can efficiently guide electricity and light along the same tiny wire, a finding that could be a step towards building computer chips capable of transporting digital information at the speed of light.
When metallic lithium forms and deposits during the charging process in a lithium-ion battery, it can lead to a reduced battery lifespan and even short circuits. Using neutron beams, scientists have now peered into the inner workings of a functioning battery without destroying it. In the process, they have resolved this so-called lithium plating mystery.
Physicists studying the effects of embedding magnetic spins onto the surface of a superconductor recently report that the spins can interact differently than previously thought. This hybrid platform could be useful for quantum simulations of complex spin systems, having the special feature that the interactions may be controllable, something quite unusual for most condensed matter systems.
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