Molecular Electronics: Electric Current Sets a Single Molecule Rotating

Electrical components are becoming ever smaller. Eventually, however, miniaturisation reaches physical limits: Even an extremely thin conductive track carrying current between components is no longer stable at room temperature when it is just a few atoms wide. Molecules can provide the necessary stability through the stronger bonds between their atoms. Researchers are therefore investigating how individual molecules can perform specific electrical functions.

A team at Karlsruhe Institute of Technology (KIT) has succeeded in developing and operating a molecular electric motor. The researchers describe an entirely new drive mechanism in Nature Chemistry: When current flows through a helical molecule, recoil from the electrons causes its moving part to rotate in a particular direction – comparable to a garden hose moving as water flows through it.

A Substantial Advance

“The new drive mechanism represents a substantial advance in our understanding of molecular electric motors,” explains co-author Dr. Lukas Gerhard from the Institute for Quantum Materials and Technologies at KIT. “While previous approaches rely on the energetic excitation of the molecule and its subsequent energy dissipation, meaning the release of energy into the surroundings, we make use of the recoil principle.” 

Using a scanning tunnelling microscope, the researchers had precisely directed current through specially made molecules and examined their response. The new mechanism could enable more energy-efficient operation. However, much more research is needed before any potential application. One possibility would be surface coatings that drive specific chemical reactions.

cka, October 28, 2026