Competition for silicon: Molecular switches enable novel devices
The development of new electronic technologies requires a constant reduction of functional components. Within the framework of an international cooperation, a team of physicists at the TU Munich has now succeeded in using a single molecule as a switching element for light signals. “Switching with just one molecule brings future electronics one step closer to the absolute limit of miniaturization,” says nanoscientist Joachim Reichert from the Physics Department of the TU Munich.
The team initially developed a method that allows molecules in strong optical fields to be contacted electrically and controlled with the aid of an applied voltage. At a voltage of about one volt, the molecule changes its structure, becoming flat, conducting and scattering light.
This optical behaviour of the molecule, which varies depending on the structure, is exciting for the researchers. This is because the scattering activity – the Raman scattering is physically exploited here – can be observed and simultaneously switched on and off with the aid of the applied voltage.
The researchers used molecules specifically synthesised by a team from Basel and Karlsruhe for their switch, which specifically change their structure when they are charged. The molecules arranged on a metal surface are contacted with a very thin metal-coated tip of a glass fragment.
This serves simultaneously as electrical contact, light source and light collector. The researchers conduct laser light to the molecule and measure tiny spectroscopic signals depending on the applied voltage. Contacting individual molecules electrically is technically extremely challenging. The scientists have now successfully combined this method with single molecule spectroscopy. In this way, the smallest structural changes in molecules can be observed extremely precisely.
One goal of molecular electronics is to develop novel devices to replace conventional silicon-based devices with integrated and directly controllable molecules.
Due to its tiny dimensions, this nano system is suitable for applications in optoelectronics where light is to be switched with electrical voltages.
More information: https://www.e20.ph.tum.de/en/start/