Scientists at Aalto University, Finland, and the University of Vienna, Austria, have combined graphene and single-walled carbon nanotubes into a transparent hybrid material with conductivity higher than either component exhibits separately
Transparent conductive films (TCFs) have many applications in touch screens, organic light emitting diodes and solar cells. These applications need materials that are strong, energy efficient and stable, which is why companies and researchers are interested in carbon-based materials. This applies especially to networks of single-walled carbon nanotubes, which are expected to replace the metal-oxide films that are currently used.
LEFT: scanning transmission electron microscope image of single-walled carbon nanotubes on graphene. Due to strong van der Waals interaction, the bundle has collapsed into a wide ribbon. RIGHT: an atomically resolved closeup of an individual tube-graphene interface
Credit: Kimmo Mustonen / Jani Kotakoski, University of Vienna
Graphene is the thinnest imaginable material, it is just one atomic layer of carbon atoms. Rolling this into a cylinder makes a carbon nanotube, which is better suited to carrying electricity in real-world applications.
In an article published in ACS Nano, scientists at Aalto University and the University of Vienna introduce a hybrid material made by combining carbon nanotubes and graphene, which improves the conductivity of the film beyond what is possible when using each of these component structures separately.
Professor Kauppinen's group at Aalto has years of experience in making carbon nanotubes for TCFs. This new work applies the techniques they have developed to place densely-packed and clean random nanotube networks on graphene. "This is another application of the technologies we have developed over the past decades. Put simply, this work is about how the two materials are put together without solvents," Kauppinen explains.
In the study, the scientists used a process called thermophoresis to deposit nanotubes on prefabricated graphene electrodes. The hybrid films' conductivities were roughly twice as high as predicted.
The experiments conducted by the team at the University of Vienna, led by Jani Kotakoski, showed that the strong electrical interactions of graphene enhanced the flow of electrons between the nanotubes by encouraging charge-tunneling.
The team used a scanning transmission electron microscope to look at the material on the scale of individual atoms, and saw that the van der Waals interaction between the graphene and nanotubes was strong enough to collapse the circular nanotube bundles into flat ribbons.
The lead scientist from the Vienna group, Kimmo Mustonen, explains: "This is really an ingenious approach. The charge transport in nanomaterials is very sensitive to any external factors. What you really want is to avoid unnecessary processing steps if your goal is to make the ideal conductive film."
Mustonen adds, "It actually is quite remarkable. We of course knew that the interaction is quite strong. For instance, think of graphite; it is just a large number of graphene layers bound together by the same mechanism. Yet we did not expect that it has such a strong impact on conductivity."
The results provide opportunities to improve the conductivity of similar hybrid nanomaterials. The article was published in "ACS Nano" in September 2019.
Esko Kauppinen | EurekAlert!
Bio-circuitry mimics synapses and neurons in a step toward sensory computing
18.10.2019 | DOE/Oak Ridge National Laboratory
Chains of atoms move at lightning speed inside metals
17.10.2019 | Linköping University
A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)
It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.
The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...
Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.
Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...
A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.
The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...
Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).
Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...
02.10.2019 | Event News
02.10.2019 | Event News
19.09.2019 | Event News
18.10.2019 | Power and Electrical Engineering
18.10.2019 | Medical Engineering
18.10.2019 | Physics and Astronomy