Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular self-assembly controls graphene-edge configuration

10.09.2014

A research team headed by Prof. Patrick Han and Prof. Taro Hitosugi at the Advanced Institute of Materials Research (AIMR), Tohoku University discovered a new bottom-up fabrication method that produces defect-free graphene nanoribbons (GNRs) with periodic zigzag-edge regions. This method, which controls GNR growth direction and length distribution, is a stepping stone towards future graphene-device fabrication by self-assembly.

Graphene, with its low dimensionality, high stability, high strength, and high charge-carrier mobility, promises to be a revolutionary material for making next-generation high-speed transistors. Moreover, graphene's properties are predicted to be directly controllable by its structure.


Graphene nanoribbons are fabricated by molecular assembly on a Cu(111) substrate. On this surface system, GNRs on grow in six azimuthal directions exclusively. White lines in the inset highlight the zigzag edges of a ribbon.

Credit: Patrick Han

For example, recent works have demonstrated that the bandgap of armchair GNRs is controlled by the ribbon width. However, the property-tailoring capabilities of other edge conformations (e.g., the zigzag edge is predicted by theory to have magnetic properties) have not been tested, because their defect-free fabrication remains a major challenge.

"Previous strategies in bottom-up molecular assemblies used inert substrates, such as gold or silver, to give molecules a lot of freedom to diffuse and react on the surface," says Han. "But this also means that the way these molecules assemble is completely determined by the intermolecular forces and by the molecular chemistry." Currently, there is no molecule that can assemble to produce zigzag-edge GNRs.

To target the zigzag edge, the AIMR team used a copper surface—a substrate more reactive than gold or silver—to introduce new substrate-to-molecule interactions, in addition to the intermolecular interactions. The effects of this strategy were demonstrated using a precursor molecule known to form armchair-edge GNRs.

On copper, scanning tunneling microscope images revealed a molecular assembly that is entirely different than that on gold or silver, yielding GNRs with periodic zigzag-edge regions. Future directions include the assessment of other reactive surfaces for bottom-up GNR fabrication, and the determination of the property-tailoring effects of the GNR edges shown in this work.

Moreover, the surface reactivity of the copper substrate also has a profound effect on both the GNR length distribution and surface growth direction. Unlike previous assemblies, the current method produces shorter ribbons, only in six surface azimuthal directions. These features could be exploited for making single graphene interconnections between prefabricated structures by self-assembly.

"Diffusion-controlled assemblies, as seen on gold and silver, produce bundles of long GNRs. These methods are good for making interconnect arrays, but not single connections", Han says. "Our method opens the possibility for self-assembling single graphene devices at desired locations, because of the length and of the direction control."

###

Publication Information

Patrick Han, Kazuto Akagi, Filippo Federici Canova, Hirotaka Mutoh, Susumu Shiraki, Katsuya Iwaya, Paul S. Weiss, Naoki Asao, Taro Hitosugi, "Bottom-Up Graphene-Nanoribbon Fabrication Reveals Chiral Edges and Enantioselectivity", ACS Nano, 2014, in press DOI: 10.1021/nn5028642

Contact Information

(About Research)
Prof. Patrick Han
Advanced Institute for Materials Research, Tohoku University
E-MAIL: pxh@wpi-aimr.tohoku.ac.jp
TEL: +81-22-217-6170

(about Public Relations)
Yasufumi NAKAMICHI
Public Relations & Outreach office, Advanced Institute for Materials Research, Tohoku University
E-MAIL: outreach@wpi-aimr.tohoku.ac.jp
TEL: +81 22 217 6146

About AIMR

The Advanced Institute for Materials Research (AIMR) at Tohoku University is one of nine World Premier International Research Center Initiative (WPI) Program established with the support of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), aimed at developing world-class research bases in Japan. After its establishment in 2007, AIMR has been active in conducting research activities and creating new systems in order to become a global center for materials science. Since 2012, AIMR has also been conducting fundamental research by finding connections between materials science and mathematics.

Learn more at http://www.wpi-aimr.tohoku.ac.jp

Yasufumi Nakamichi | Eurek Alert!

Further reports about: GNR GNRs Molecular controls copper graphene materials properties self-assembly

More articles from Materials Sciences:

nachricht New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University

nachricht Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>