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Firefly Structures Can Boost OLED Efficiency

Fireflies could help make organic light-emitting diodes (OLEDs) significantly more efficient, Korean researchers say.

Fireflies, which generate bioluminescent light more efficiently than many other animals, use their glow to attract mates. Previous research suggests that this efficiency was due not only to the chemicals that the insects use to produce light, but also to the lantern that holds these chemicals.

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Mismatched 2-D Layers Combine to Create New Optoelectronic Devices

Researchers have had success in using two-dimensional (2-D) materials to fabricate layered structures through epitaxy (the growth of crystals on a substrate), but only if they shared similar crystal lattices.

Now researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL) have shown that 2-D materials with dissimilar crystal lattices can still be grown together using epitaxy techniques. The ORNL team was able to grow a layer of gallium selenide—a p-type semiconductor—on top of molybdenum diselenide—an n-type semiconductor. This combination resulted in an atomically thin solar cell.

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Tesla Coil Remotely Induces Nanotubes to Self Assemble

Nikola Tesla conjured up all sorts of interesting experiments for his famed “Tesla Coils.” Today, however, their main use has been relegated largely to impressing visitors at science museums.

That is about to change. Researchers at Rice University have used Tesla coils to get carbon nanotubes to self-assemble into long chains, a phenomenon the scientists have dubbed “Teslaphoresis.” Controlled assembly of nanomaterials from the bottom up could be useful in applications including regenerative medicine where the nanotubes would act as nerves as well as fabricating electronic circuits without touching them.

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One-Step Process Could Lead to Roll-to-Roll Production of Touchscreen Displays

Touchscreen displays have two types of conductor paths that enable a finger tap or swipe to trigger some response. There are those that cover the display so that when a finger passes over them, they open and close circuits. Then there are the larger conductor paths that are on the edges of the display, where all the smaller ones converge.

This design has always required a multiple-step manufacturing process that has made production costs high. Now researchers at the Leibniz Institute for New Materials (INM) in Germany have developed a one-step process for producing both of these conductor paths that should dramatically reduce manufacturing costs for touchscreen displays.

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White Graphene Helps Batteries Keep Their Cool in High Temperatures

While this blog has devoted a fair amount of attention to the use of nanomaterials to improve the charge capacity of electrodes in Li-ion batteries, mentions of research into the use of nanomaterials for electrolytes and separators has been more scarce on these pages. Nonetheless, a lot of research is going on with the aim of improving the thermal stability of Li-ion batteries’ electrolytes and separators.

Now, researchers at Rice University are combining their work on improving the thermal stability of electrolytes with research into separators made from a new material: hexagonal boron nitride. In research described in the journal Advanced Energy Materials, the researchers were able to produce a Li-ion battery that operated for more than a month at temperatures as high as 150 degrees Celsius (302 °F) with very little loss of efficiency.

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Graphene Filter Could Make Wireless Data Transmission 10 Times Faster

Researchers at Ecole Polytechnique Fédérale de Lausanne (EPFL) and the University of Geneva in Switzerland have developed a graphene filter for microchips that could potentially lead to wireless transmission rates 10 times as fast what chips deliver today.

In research described in the journal Nature Communications, the Swiss researchers actually fabricated what is known as a non-reciprocal isolator. The isolator filters backward radiation, preventing waves from being reflected back towards their source.

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Wafer-scale Nanotube Film Is Finally Here

Single-walled carbon nanotubes (SWCNTs) used to be the darling of those who were looking for an alternative to silicon in digital electronics. The first SWCNT-based transistors were fashioned almost twenty years ago, but scaling up the use of SWCNTs since then to very large scale integration (VLSI) processes has remained elusive.

There were two persistent problems with SWCNTs that led to much of the research community pursuing graphene instead of SWCNTs as the next great post-silicon hope: an inconsistency between semiconducting and metallic nanotubes and the frustration of trying to get all of the nanotubes to align on a wafer.

Now researchers at Rice University claim that they have struck upon a method that produces a uniform and wafer-scale film of highly aligned and densely packed SWCNTs that may finally deliver on the long-promised potential of SWCNTs.

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2-D Boron Is an Intrinsic Superconductor

Just as we were getting confirmation that graphene could be coaxed into behaving as a superconductor, we now get research out of Rice University indicating that the two-dimensional version of boron may be the only flatlands material that is an intrinsic superconductor.

Researchers at Rice, led by Boris Yakobson, have used computer calculations to determine that boron is a natural low-temperature superconductor, and may, in fact, be the only 2-D material with this intrinsic property.

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World's Smallest Diode Is Made of DNA

Scientists have now created what they say is the world's smallest diode, one the size of a single (rather short) molecule of a DNA. This work could help spur development of DNA components for molecular electronics, its creators claim.

Diodes—also known as rectifiers—allow electric current to flow in just one direction. More than 40 years ago, scientists proposed miniaturizing diodes and other electronic components down to the size of single molecules, an idea that eventually helped give birth to the field of molecular electronics, which could help push computing beyond the limits of conventional silicon devices. [See “Whatever Happened to the Molecular Computer?IEEE Spectrum, October 2015]

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Light Could Become the Dominant Form of Heat Transfer

We know that when you touch a hot cup of tea it can warm your hands. That’s heat conduction: Two surfaces of different temperatures make physical contact and heat is transferred from one to the other. We are also pretty aware of convective heat transfer, though it may not be quite as simple. In convection, the heat transfer occurs when a fluid—this can be air, some other gas, or even a liquid—is caused to move away from a source of heat and in the process carries energy with it. For instance, above the hot surface of a stove, the air being warmed expands, becomes less dense than the surrounding cold air, and rises.

The reason for this elementary explanation of heat transfer is to set them apart from another means of thermal energy transfer. Objects can also transfer heat to their surroundings using light, but that method of heat exchange has always been thought to be very weak compared with conduction and convection. Now, in collaborative research among researchers at Columbia, Cornell, and Stanford, they discovered that we just weren’t doing it right. Their conclusion: light could become the most dominant form of heat exchange between objects.

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
Editor
Dexter Johnson
Madrid, Spain
 
Contributor
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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