Research Shows Graphene Can Enhance Power Of Light
28 February 2013
Scientists have discovered that graphene—the material that promises to revolutionize the global economy in the years to come, the way plastic did over the last century—can multiply the power of light by converting a single proton that it absorbs into multiple electrons that could drive electric currents.
The promising new discovery published in Nature Physics makes graphene a key alternative material for light detection and harvesting technologies, which are currently based on conventional semiconductors like silicon.
The discovery is the result of collaboration between researchers at the Institute of Photonic Science (ICFO), Massachusetts Institute of Technology (MIT), Germany's Max Planck Institute for Polymer Research and Spain's Graphenea S.L. Donostia-San Sebastian.
In most materials, one absorbed photon generates one electron. However, in the case of graphene, one absorbed photon is able to produce many excited electrons, thus generating larger electrical signals, said Frank Koppens, group leader at ICFO. This ability makes graphene the perfect material for any device that depends on converting light into electricity.
The experiment included sending a known number of photons with different energies (different colors) onto a monolayer of graphene. The team found that high energy photons (e.g. violet) were converted into a larger number of excited electrons than low energy photons (e.g. infrared). It was known that graphene is able to absorb a very large spectrum of light colors but now it has been shown that once the material has absorbed light, the energy conversion efficiency is very high.
The next challenge will be to find out how to extract the electrical current and increase the absorption of graphene to be able to design graphene devices that detect light more efficiently and potentially make more efficient solar cells.