The new optical metamaterial is composed of the purest graphene possible. All it takes to generate a photocurrent from incoming light is chopping the material up in to some kind of special configuration. No separate junctions are required to produce electricity. The new discovery could yield implications for solar energy.
Graphene is an artificial nano-structure composed of carbon atoms that combine to create a hexagonal lattice so that each atom is placed on the corner of one of these hexagons. It is an extremely versatile, powerful material capable of absorbing thermal and kinetic energy, as well as converting that energy and light in to electricity. Graphene qubits are currently being used in quantum computers due to their adjustable voltage. Under the right conditions the material demonstrates superconductive properties, can shield an area from radiation or even harden upon impact. On top of all that Graphene is 200 times stronger and 6 times lighter then steel.
Metamaterials are very interesting in that they demonstrate unique properties distinct from the element or compound they are made of. All that is required is arranging them in to some kind of special geometric configuration. At this point, there are several graphene metamaterials including one that is created by stacking two single atom thick layers on top of each other, and another one that is formed by rotating those same layers 1.1 degrees out of alignment.
In this new international project co-led by a physicist at the University of California, scientists have figured out how to make the newly discovered pristine graphene even more powerful by chopping it up in to unique formations. Back in November scientists announced they had created the purest graphene ever, and that the newly purified carbon nano-structure shatters all previous records for conductivity. Now they hope to transform pristine graphene in to a new kind of high performance optical metamaterial by reshaping the hexagonal lattice. The results could yield yet another improvement to solar power enabled by graphene.
“We found that photocurrents may arise in pristine graphene under a special condition in which the entire sheet of graphene is completely free of excess electronic charge” i.e. pristine
“Generating the photocurrent requires no special junctions and can instead be controlled, surprisingly, by simply cutting and shaping the graphene sheet into unusual configurations, from ladder-like linear arrays of contacts, to narrowly constricted rectangles, to tapered and terraced edges.”
Photocurrents are a kind of electrical charge produced by contact with light. In other words, all that’s required for the graphene to generate electricity is assembling the material in to a very specific collection of shapes. Scientists connect narrow ribbons and crosses to wide open rectangular regions. When light illuminates the narrow ribbon electricity is generated, just like that.
Currently solar panels require separate junctions composed of a semi- conductor material. Now with pristine graphene they may be able to construct solar panels that require no junction at all.
Using graphene to improve solar power is not new by any stretch of the imagination, although it has gained a lot of traction over the past year. Just a few weeks ago scientists came up with a graphene hybrid solar panel that generates electricity from rain. Several months before that they even figured out how to improve a multi-junction solar panel by including a layer of graphene.