Forum for Science, Industry and Business

Molecular switch will facilitate the development of pioneering electro-optical devices

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative effort, a team of physicists at the Technical University of Munich has succeeded to use single molecules as switching elements for light signals.

Electrically switchable organic molecule.

Image: Yuxiang Gong / TUM / Journal of the American Chemical Society

"Switching with just a single molecule brings future electronics one step closer to the ultimate limit of miniaturization," says nanoscientist Joachim Reichert from the Physics Department of the Technical University of Munich.

Different structure – different optical properties

The team initially developed a method that allowed them to create precise electrical contacts with molecules in strong optical fields and to address them using an applied voltage. At a potential difference of around one volt, the molecule changes its structure: It becomes flat, conductive and scatters light.

This optical behavior, which strongly depends on the structure of the molecule, is quite exciting for the researchers because the scattering activity – Raman scattering, in this case – can be both observed and, at the same time, switched on and off via an applied voltage.

Challenging technology

The researchers used molecules synthesized by a team based in Basel and Karlsruhe. The molecules change their structure in a specific way when they get charged. They are arranged on a metal surface and contacted using the corner of a glass fragment with a very thin metal coating as a tip.

This serves as an electrical contact, light source and light collector, all in one. The researchers used the fragment to direct laser light to the molecule and measure tiny spectroscopic signals that vary with the applied voltage.

Establishing reliable electric contacts between individual molecules is extremely challenging from a technical point of view. The scientists have now successfully combined this procedure with single-molecule spectroscopy, allowing them to observe even the smallest structural changes in molecules with great precision.

Competition for Silicon

One goal of molecular electronics is to develop novel devices that can replace traditional silicon-based components using integrated and directly addressable molecules.

Thanks to its tiny dimensions, this nanosystem is suitable for applications in optoelectronics, in which light needs to be switched by an electrical potential.

Publication:

Hai Bi, Carlos-Andres Palma, Yuxiang Gong, Peter Hasch, Mark Elbing, Marcel Mayor, Joachim Reichert und Johannes V. Barth,
Voltage-Driven Conformational Switching with Distinct Raman Signature in a Single-Molecule Junction: J. Am. Chem. Soc. 140, 14, 4835-4840
Link: http://dx.doi.org/10.1021/jacs.7b12818

Further information

The research project was funded by the German Research Foundation (DFG) via the Cluster of Excellence Munich-Centre for Advanced Photonics (MAP) and the SPP 1243, as well as the European Union (ERC Advanced Grant MolArt and FET Measure 2D-ink) and the China Scholarship Council (CSC).

Contact:

Dr. Joachim Reichert / Prof. Dr. Johannes Barth
Technical University of Munich
Surface and Interface Physics (E20)
Tel.: +49 89 289 12608 – E-Mail: e20office@ph.tum.de
http://www.e20.ph.tum.de/en/

Weitere Informationen:

https://www.tum.de/nc/en/about-tum/news/press-releases/detail/article/34665/ Link to the press release

Dr. Ulrich Marsch | Technische Universität München

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...