The challenge to miniaturise light emitting diodes (LEDs) has been met by a team of researchers in France, bring us a step closer to molecular computers.
The Institut de Physique et de Chimie des Matériaux de Strasbourg (IPCMS, CNRS/Université de Strasbourg), in collaboration with UPMC and CEA, has developed the first ever single-molecule LED. The device is formed from a single polythiophene wire placed between the tip of a scanning tunnelling microscope and a gold surface.
It emits light only when the current passes in a certain direction. As well as shedding light on the interactions between electrons and photons at the smallest scale, the work represents an advance towards creating components for a molecular computer.
Polythiophene (comprising hydrogen, carbon and sulphur) is a good conductor of electricity and is used to make the larger LEDs that are already on the market. The reseachers observed that light was only emitted when electrons travelled from the tip of the scanning tunnelling microscope towards the gold surface. When the polarity was reversed, light emission was negligible.
With the help of theoretical physicists, the researchers showed that this light was emitted when a negative charge (an electron) combined with a positive charge (a hole) in the nanowire and transmitted most of its energy to a photon. For every 100,000 electrons injected into the thiophene wire, a photon was emitted (its wavelength being in the red end of the spectrum).
The device gives researchers a new tool to probe phenomena that are produced when an electrical conductor emits light at the quantum scale. Moreover, the researchers believe they have taken a first step towards making molecule-sized components that combine electronic and optical properties; such components could form the basis of a molecular computer.
It emits light only when the current passes in a certain direction. As well as shedding light on the interactions between electrons and photons at the smallest scale, the work represents an advance towards creating components for a molecular computer.
Polythiophene (comprising hydrogen, carbon and sulphur) is a good conductor of electricity and is used to make the larger LEDs that are already on the market. The reseachers observed that light was only emitted when electrons travelled from the tip of the scanning tunnelling microscope towards the gold surface. When the polarity was reversed, light emission was negligible.
With the help of theoretical physicists, the researchers showed that this light was emitted when a negative charge (an electron) combined with a positive charge (a hole) in the nanowire and transmitted most of its energy to a photon. For every 100,000 electrons injected into the thiophene wire, a photon was emitted (its wavelength being in the red end of the spectrum).
The device gives researchers a new tool to probe phenomena that are produced when an electrical conductor emits light at the quantum scale. Moreover, the researchers believe they have taken a first step towards making molecule-sized components that combine electronic and optical properties; such components could form the basis of a molecular computer.