MIT Researchers discover that Graphene (aka "wonder material") creates electricity when struck by light. This new discovery could revolutionize solar power, medicine, astronomy, photography and defense

Extreme Tech

 

Oh graphene! The cheap, easy-to-manufacture one-atom-thick sheet of carbon can add yet another weird, fantastical, and possibly life-changing ability to its list of characteristics: it has an incredibly sensitive thermoelectric response to light. In layman’s terms: graphene, when struck by light of almost any wavelength, can produce an electric current.

The discovery was made by a team of researchers from MIT in the US and the National Institute for Materials Science in Japan. A sheet of graphene was treated so that it had two regions with different electrical properties (a p-n junction). Then, by shining an 850nm infrared laser on the material a temperature difference between the two regions is created, and an electrical current flows. This effect is caused by a hot carrier response, where the electrons gain enough energy to move, but the underlying lattice of carbon stays cool.

Now, this is significant because a hot carrier response has only ever been observed in materials that are reduced to (almost) absolute zero, or when an intensely powerful laser is used to heat the material. Graphene’s hot carrier response occurs at room temperature and across a wide range of frequencies, and — most importantly — it only requires a very weak source of light to trigger the effect.

Since its discovery in 2004 (by pulling a thin layer off a piece of pencil graphite using sticky tape) a host of unique electronic, mechanic, and optic properties have led graphene to be dubbed a “wonder material” — and in this new discovery, all three of these spheres overlap to produce an effect that could revolutionize solar power, medicine, astronomy, photography, defense, and more.

 

It should be stressed that this is just a preliminary discovery, and so it’s hard to divine what the ultimate applications might be, but we can definitely do some educated guesstimating. First, this thermoelectric effect could be used in solar panels. Current photovoltaic panels based on silicon technology are only sensitive to a fraction of the sun’s emitted wavelengths — a graphene solar panel could be cheaper to make and more efficient. In biology, this effect could be used to detect disease and toxin molecules, many of which emit a small amount of light when illuminated from an outside source.

In astronomy and photography, graphene could be used as a highly-sensitive photodetector that works across a huge swath of the spectrum, including infrared which many sensors struggle with. The same tech could be applied to night-vision goggles for military use — and of course, in almost every case listed above, graphene would be a cheaper alternative to the current solutions.

All this, from a material that was only isolated a few years ago! In the long run, we really don’t know the full extent of what graphene-based technologies will enable us to do; it will probably be all of the above and then some.

Read more about graphene, or about MIT’s discovery

[Image credit: University of Manchester]