Flickering light: Electrical impulse

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  • Published: Apr 1, 2018
  • Author: David Bradley
  • Channels: Infrared Spectroscopy
thumbnail image: Flickering light: Electrical impulse

Generator

Blowin’ in the wind, Magnus Jonsson och Mina Shiran Chaharsoughi Photo credit: Thor Balkhed

A material that generates an electrical impulse when sunlight flickers over it has been developed by researchers at the Laboratory of Organic Electronics at Linköping University, Sweden and their colleagues, the work extends an infrared materials previously developed by the team.

"Plants and their photosynthesis systems are continuously subjected to fluctuations between sunshine and shade, explains principal investigator Magnus Jonsson."We have drawn inspiration from this and developed a combination of materials in which changes in heating between sunshine and shade generate electricity." The team has now corroborated their findings with both experiment and computer simulations, which they detail in the journal Advanced Optical Materials.

Jonsson and his colleagues worked with a team from the University of Gothenburg previously to develop nanoantennae that absorb sunlight and generate heat. They described details of that material in the journal Nano Letters in 2017. At the time, they suggested that the nanoantennae could be incorporated into window glass to reduce cold downdraughts and save energy. The nanoantennae reacted to near infrared light and generate heat.

Pyroelectric

Now, team member Mina Shiran Chaharsoughi has developed the technology further and created a tiny optical generator by combining the nanoantennae with a pyroelectric film. In pyroelectric materials an electrical voltage is developed when the substance is heated or cooled as the change in temperature causes charges to move. The nanoantennae consist of small metal discs, in this case gold nanodiscs, with a diameter of 160 nanometres. The team places them on a substrate and coats this with a polarised polymer film to allow the pyroelectric phenomenon to be manifest. The nanoantennae can be manufactured across a large area, with billions of the small discs uniformly distributed over the surface. The spacing between discs in the present study is about 0.3 micrometres. "We have used gold and silver, but they can also be manufactured from aluminium or copper," explains Magnus Jonsson. The degree of polarisation affects the magnitude of the generated power, while the thickness of the polymer film apparently has no effect on the current generated.

Optical sensor

"We force the polarisation into the material, and it remains polarised for a long time," explains Mina Shiran Chaharsoughi. Jonsson adds that, "The research is at an early stage, but we may in the future be able to use the natural fluctuations between sunshine and shade in trees to harvest energy." There are more immediate applications in optics research of course. For instance, the system might be used to create a nanoscopic light detector or tiny switching devices for optical computing.

Related Links

Adv Opt Mater 2018, online: "Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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