The October 2023 issue of IEEE Spectrum is here!

Close bar

First Single-Molecule LED

Researchers have made the smallest possible organic light-emitting diode

1 min read
First Single-Molecule LED
APS

Illustration: APS
Artist illustration of a single-molecule organic light-emitting diode

By coaxing light out of a single polymer molecule, researchers have made the world’s tiniest light-emitting diode. This work is part of an interdisciplinary effort to make molecular scale electronic devices, which hold the potential for creating smaller but more powerful and energy-efficient computers.

Guillaume Schull and his colleagues at the University of Strasbourg in France made the device with the conducting polymer polythiophene. They used a scanning tunneling microscope tip to locate and grab a single polythiophene molecule lying on a gold substrate. Then they pulled up the tip to suspend the molecule like a wire between the tip and the substrate.

The researchers report in the journal Physical Review Letters that when they applied a voltage across the molecule, they were able to measure a nanoampere-scale current passing through it and to record light emitted from it.

Conventional organic light-emitting diodes are semiconductors sandwiched between two electrodes. A voltage applied between the electrodes creates electrons and holes. When these two oppositely charged particles meet, photons are emitted.

The same thing happens here, except on a much tinier, single-molecule level. When the microscope tip had a large negative voltage, the researchers calculate that one photon was emitted for every 100 000 electrons that surged from the tip and into the molecule. The photon had a red wavelength. When the researchers flipped the voltage bias, the light emission was negligible.

The Conversation (0)
back view of man in baseball cap holding controllers for robot arms, which are in silhouette in front of him, just outside of the shadows

Video Friday: Good Behaviors

3 min read