Duke University chemists created a new set of flexible, electrically conductive nanowires from thin strands of copper atoms mixed with nickel. The copper-nickel nanowires, in the form of a film, conduct electricity even under conditions that break down the transfer of electrons in plain silver and copper nanowires, a new study shows.
Because films made with copper-nickel nanowires are stable and are relatively inexpensive to create, they are an attractive option to use in printed electronics, products like electronic paper, smart packaging and interactive clothing, said Benjamin Wiley, an assistant professor of chemistry at Duke. His team describes the new nanowires in a NanoLetters paper published online May 29.
The new copper-nickel nanowires are the latest nanomaterial Wiley's lab has developed as a possible low-cost alternative to indium tin oxide, or ITO. This material is coated on glass to form the transparent conductive layer in the display screens of cell phones, e-readers and iPads.
Indium, at $600 - $800 per kilogram, is an expensive rare-earth element. Most of it is mined and exported from China, which is reducing exports, causing indium's price to increase. Indium tin oxide is deposited as a vapor in a relatively slow, expensive coating process, adding to its cost. And the film is brittle, which is a major reason the signature pads at grocery store checkout lines eventually fail and why there is not yet a flexible, rollable iPad.
Last year, Wiley's lab created copper nanowire films that can be deposited from a liquid in a fast, inexpensive coating process. These conductive films are much more flexible than the current ITO film. Copper is also one-thousand times more abundant and one-hundred times cheaper than indium. One problem with copper nanowire films, however, is that they have an orange tint that would not be desirable in a display screen. The copper-based films also oxidize gradually when exposed to air, suffering from the same chemical reaction that turns the Statue of Liberty or an old penny green, Wiley said.
Nickels, however, rarely turn green. Inspired by the U.S. five-cent piece, Wiley wondered if he could prevent oxidation of the copper nanowires by adding nickel. He and his graduate student, Aaron Rathmell, developed a method of mixing nickel into the copper nanowires by heating them in a nickel salt solution.
"Within a few minutes, the nanowires become much more grey in color," Wiley said.
Rathmell and Wiley then baked the new nanowires at various temperatures to test how long they conducted electricity and resisted oxidation. The tests show that the copper-nickel nanowire films would have to sit in air at room temperature for 400 years before losing 50 percent of their electrical conductivity. Silver nanowires would lose half of their conductivity in 36 months under the same conditions. Plain copper nanowires would last only 3 months.
While the copper-nickel nanowires stack up against silver and copper alone, they aren't going to replace indium-tin-oxide in flat-panel displays any time soon, Wiley said, explaining that, for films with similar transparency, copper-nickel nanowire films cannot yet conduct the same amount of electricity as ITO. "Instead, we're currently focusing on applications where ITO can't go, like printed electronics," he said.
The greater stability of copper-nickel nanowires makes them a better alternative to both copper and silver for applications that require a stable level of electrical conductivity for more than a few years, which is important for certain printed electronics applications, Wiley said.
He explained that printed electronics combine conductive or electronically active inks with the printing processes that make magazines, consumer packaging and clothing designs. The low cost and high speed of these printing processes make them attractive for the production of solar cells, LEDs, plastic packaging and clothing.
A Durham, NC startup company, NanoForge Corp., which Wiley co-founded has begun manufacturing copper-nickel nanowires to test in these and other potential applications.
"Synthesis of Oxidation-Resistant Cupronickel Nanowires for Transparent Conducting Nanowire Networks'" Rathmell, A. R., Nguyen, M., Chi, M. and Wiley, B. J. NanoLetters, May 29, 2012. DOI: 10.1021/nl301168r
Ashley Yeager | EurekAlert!
Researchers measure near-perfect performance in low-cost semiconductors
18.03.2019 | Stanford University
Robot arms with the flexibility of an elephant’s trunk
18.03.2019 | Universität des Saarlandes
DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.
The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
25.03.2019 | Trade Fair News
25.03.2019 | Life Sciences
25.03.2019 | Information Technology