Can silver nanodiscs raise ultra-thin MoS2’s LED performance potential?
With enhanced light emission properties, MoS2 could make a good candidate for light emitting diode technologies.
Monolayer MoS2’s ultra-thin structure is strong, lightweight, and flexible, which makes the material a good candidate for many applications, such as high-performance, flexible electronics. Such a thin semiconducting material, however, has little interaction with light, limiting the material’s use in light emitting and absorbing applications.
“The problem with these materials is that they are just one monolayer thick,” said Koray Aydin, assistant professor of electrical engineering and computer science at the McCormick School of Engineering. “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 optoelectric applications, we needed to increase their interactions with light.”
Aydin and his team tackled this problem by combining nanotechnology, materials science, and plasmonics, the study of the interactions between light and metal.
The team discovered that the nanodiscs enhanced light emission and determined the specific diameter of the most successful disc, which is 130 nanometers.
“We have known that these plasmonic nanostructures have the ability to attract and trap light in a small volume,” said Serkan Butun, a postdoctoral researcher in Aydin’s lab. “Now we’ve shown that placing silver nanodiscs over the material results in twelve times more light emission.”
The use of the nanostructures – as opposed to using a continuous film to cover the MoS2 – allows the material to retain its flexible nature and natural mechanical properties.
The team’s next step is to use the same strategy for increasing the material’s light absorption abilities to create a better material for solar cells and photodetectors.
“This is a huge step, but it is not the end of the story,” Aydin said. “There might be ways to enhance light emission even further. But, so far, we have successfully shown that it’s indeed possible to increase light emission from a very thin material.”
Supported by Northwestern’s Materials Research Science and Engineering Center and the Institute for Sustainability and Energy at Northwestern, the research is described in the March 2015 online issue of NanoLetters. Butun is first author of the paper. Sefaatiin Tongay, assistant professor of materials science and engineering at Arizona State University, provided the large-area monolayer MoS2 material used in the study.
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www.mccormick.northwestern.edu
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