Researchers from the ICFO, ICREA, MIT and UC Riverside, have now showed that a graphene-based photodetector converts absorbed light into an electrical voltage at an extremely high speed. The efficient conversion of light into electricity is crucial to various technologies, from cameras to solar cells. It can also play a part in data communication applications, since it allows information to be carried by light and converted into electrical information that can be processed in electrical circuits.

Graphene is known to be an excellent material for conversion of light to electrical signals, but it was unknown exactly how fast graphene responds to ultrashort flashes of light. The researchers developed a device capable of converting light into electricity in less than 50 femtoseconds (a twentieth of a millionth of a millionth of a second). Facilitated by graphene's nonlinear photo-thermoelectric response, the observation of femtosecond photodetection response times was enabled.