Optical cavity helps graphene soak up more light
Graphene, the 2D wonder material made up of a sheet of carbon one atom thick, has a long list of superpowers, but one thing it hasn't been great at is absorbing light. Now, a study from the University of Central Florida (UCF) has found a way to boost graphene's light absorption, allowing it to make better use of that energy.
Normally, graphene can only absorb less than two percent of the visible light spectrum. In attempting to boost that statistic, previous studies have embedded metal particles onto sheets of graphene, but that just resulted in the metal itself absorbing the light with little benefit to the material underneath.
In the new study, the UCF team decided to alter the shape of the graphene but not the composition of the material. To do that, the researchers first placed it on a polymer substrate, then stamped a nanoscale pattern into the graphene. That created an optical cavity in the material, so that when light hits it, the waves bounce back and forth between the faces of the graphene. That lets the material absorb far more of the light than it normally would.
The researchers say that their design allowed a single layer of graphene to absorb more than 45 percent of the light that hits it, but with further optimization they believe that figure could reach almost 90 percent.
The technique is also dynamically tunable, allowing the graphene to absorb different wavelengths of light as needed. That means it could have eventual applications in optoelectronic devices, like night vision systems, infrared cameras, gas and chemical sensors, touchscreens, and glucose testing devices.
The research was published in the journal Physical Review B.
Source: University of Central Florida