Plasmonic Nanodiscs Boost 2-D Material’s Light Emission

Augmenting molybdenum disulfide with plasmonic nanodiscs transforms the 2-D material into a promising light emitter.

Researchers at Northwestern and Arizona State universities have found that a periodic array of 130-nm silver discs on top of a sheet of MoS₂ enhances the semiconductor’s light emission as much as 12 times. The use of nanostructures instead of a continuous film allows the material to retain its flexibility.

“We have known that these plasmonic nanostructures have the ability to attract and trap light in a small volume,” said Northwestern postdoctoral researcher Serkan Butun. “Now we’ve shown that placing silver nanodiscs over the material results in 12 times more light emission.”

Silver nanodiscs on monolayer molybdenun disulfide. Courtesy of Northwestern University.

The effect stems “from the fact that plasmonic resonance couples to both excitation and emission fields and thus boosts the light-matter interaction at the nanoscale,” the researchers wrote in Nano Letters (doi: 10.1021/acs.nanolett.5b00407). Similar engineering of other 2-D materials could lead to a new breed of photodetectors, sensors and photovoltaic devices, they said.

Monolayer MoS₂ is strong, lightweight and flexible, making it a good candidate for applications such as flexible electronics. But on its own, the material has very little interaction with light, limiting its use in light-emitting and -absorbing applications.

“The problem with these materials is that they are just one monolayer thick,” said Northwestern professor Dr. Koray Aydin. “So the amount of material that is available for light emission or light absorption is very limited. In order to use these materials for practical photonic and opto-electric applications, we needed to increase their interactions with light.”

For more information, visit www.northwestern.edu.