Near-perfect light absorption by UMN team

Utilizing the bizarre capabilities of two-dimensional materials, researchers from the University of Minnesota, for the first time, have engineered an atomically thin material made from layers of molybdenum disulfide and graphene that can absorb nearly 100% light at room temperature, a discovery that could prove efficacious for a wide range of applications from optical communications to stealth technology.

The scientists detailed their finding in "Achieving near-perfect light absorption in atomically thin transition metal dichalcogenides through band nesting," a paper published in Nature Communications that details the team's near-perfect light absorbers (NPLAs), with an absorbance of at least 99%.

In light absorption, the frequency of the incoming light wave is at or near the energy levels of the electrons in the material – the electrons will take in the photons and change their energy state either by spitting them back out (reflecting) or heating up the material the electrons comprise.

Materials that absorb nearly all incident light or just naturally occurring illumination from a photon source, are valuable for applications that involve detecting or controlling light.

"Optical communications are used in basically everything we do," said Steven Koester, a professor at the College of Science and Engineering and a senior author of the paper. "The Internet, for example, has optical detectors connecting fiber optic links. This research has the potential to allow these optical communications to be done at higher speeds and with greater efficiency."

The researchers made this "near-perfect absorber" possible by using a technique called band nesting to manipulate the already unique electrical properties in a material made up of only two to three layers of atoms.

Their fabrication method is simple, low-cost and requires no nanopatterning (tiny etching) methods, which means it is easier to scale up than that of other light-absorbing materials being studied.

"The fact that we are able to achieve this near-perfect light absorption at room temperature with only two or three atomic layers of material is really the key innovation here," said Tony Low, an associate professor in the College of Science and Engineering. "And we were able to do that without using any complex and expensive patterning techniques, which could allow us to make perfect absorbers in a more feasible and cost-effective way."

With a material that is almost 100% effective at absorbing light, aside from the telecommunications and military aspects, perhaps it could be used in the energy sector as well to improve efficiencies in solar panels or to recycle the light put off in large cities.