Molybdenum disulfide light absorption study via plasma nanostructures

When molybdenum disulfide met light about two years ago, MIT scientists began investigating the potential of molybdenum disulfide (MoS2) as a photovoltaic material. The result was a bit of a mess. They concluded that the conversion efficiency of the material was very low, but another encouraging finding was that by squeezing three pieces of molybdenum disulfide down to a nanometer thick, the material could absorb 10% of direct sunlight. That's an order of magnitude more sunlight than gallium arsenide and silicon can absorb.

Molybdenum disulfide investigation of enhancing light absorption 

While the discovery of this new material is encouraging, it's not enough to get everyone clamoring for molybdenum disulfide to replace silicon in photovoltaics and other photovoltaic materials.  

Now, researchers at Northwestern University are synthesizing molybdenum disulfide with plasmonics to further improve the material's light absorption and photoluminescence properties.

The use of plasma nanostructures to enhance solar photovoltaic effects is not new.  Back in 2012, researchers at Princeton University developed a plasma nanostructure that can be used in a sampler cell to absorb 96 percent of the light hitting a material's surface and improve its electrical conversion efficiency by about 175 percent.

Plasma primions use the oscillations that occur when photons hit dense electrons on a metal surface.  In addition to plasma applications in photovoltaics, plasma primitives have many other potential applications, including data transfer and high-resolution lithography on computer chips.

Using plasmonic Silver Nanodisc Arrays, the Northwestern team was able to significantly enhance the photoexcitation effects of molybdenum disulfide, according to a study in Nano Letters.

We already know that these plasma nanostructures have the ability to attract and trap small amounts of light.  Serkan Butun, a postdoctoral researcher.  "Now we have shown that by placing silver nanosheets on the surface of [molybdenum disulphide] material, you can increase light emission by more than 12 times."  

This 12-fold increase in light emission is due to the coupling of plasmon resonance with light excitation and emission, which enhances the interaction between light and nanomaterials.  

The researchers believe that the photoemission enhancement effect will lead to the application of molybdenum disulfide in light-emitting diodes. 

This is a huge step forward, but it is not the end of the story.  Koray Aydin, director of the project, said in an interview.  There are ways to further enhance light emission, but we haven't found them yet.  The most effective way to increase light emission is with our ultra-thin molybdenum disulfide material.