27 March 2018

It may in the future be possible to harvest energy with the aid of leaves fluttering in the wind. Researchers at the Laboratory of Organic Electronics at Linköping University have developed a method and a material that generate an electrical impulse when the light fluctuates from sunshine to shade and vice versa.

Magnus Jonsson and Mina Shiran Chaharsoughi Magnus Jonsson and Mina Shiran Chaharsoughi Photo credit: Thor Balkhed“Plants and their photosynthesis systems are continuously subjected to fluctuations between sunshine and shade. We have drawn inspiration from this and developed a combination of materials in which changes in heating between sunshine and shade generate electricity,” says Magnus Jonsson, docent and principal investigator for the research group in organic photonics and nano-optics at the Laboratory of Organic Electronics, Linköping University.

The results, which have been verified in both experiments and computer simulations, have been published in Advanced Optical Materials.

Nanoantennas

Together with researchers from the University of Gothenburg, Magnus Jonsson and his team have previously developed small nanoantennas that absorb sunlight and generate heat. They published an article together in Nano Letters in 2017, describing how the antennas when incorporated into window glass could reduce cold downdraughts and save energy. The antennas, with dimensions in the order of tens of nanometers, react to near infrared light and generate heat.

Mina Shiran Chaharsoughi, PhD student in Magnus Jonsson’s group, has now developed the technology further and created a tiny optical generator by combining the small antennas with a pyroelectric film.

“Pyroelectric” means that an electrical voltage develops across the material when it is heated or cooled. The change of temperature causes charges to move and the generation of an electric current in the circuit.

The antennas consist of small metal discs, in this case gold nanodiscs, with a diameter of 160 nm (0.16 micrometres). They are placed on a substrate and coated with a polymeric film to create the pyroelectric properties.

Large areas

“The nanoantennas can be manufactured across large areas, with billions of the small discs uniformly distributed over the surface. The spacing between discs in our case is approximately 0.3 micrometres. We have used gold and silver, but they can also be manufactured from aluminium or copper,” says Magnus Jonsson.

Blowin’ in the wind, Magnus Jonsson och Mina Shiran ChaharsoughiBlowin’ in the wind, Magnus Jonsson och Mina Shiran Chaharsoughi Photo credit: Thor BalkhedThe antennas generate heat that is then converted to electricity with the aid of the polymer. It is first necessary to polarize the polymer film in order to create a dipole across it, with a clear difference between positive and negative charge. The degree of polarisation affects the magnitude of the generated power, while the thickness of the polymer film seems not to have any effect at all.

“We force the polarisation into the material, and it remains polarised for a long time,” says Mina Shiran Chaharsoughi.

Air from a fan

Mina Shiran Chaharsoughi carried out an experiment in order to demonstrate the effect clearly, holding a twig with leaves in the air flow from a fan. The motion of the leaves created sunshine and shade on the optical generator, which in turn produced small electrical pulses and powered an external circuit.

“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,” says Magnus Jonsson.

Applications that are closer to hand can be found in optics research, such as the detection of light at the nanometre scale. Other applications may be found in optical computing.

Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations,
Mina Shiran Chaharsoughi, Daniel Tordera, Andrea Grimoldi, Isak Engquist, Magnus Berggren, Simone Fabiano, Magnus P. Jonsson, Laboratory of Organic Electronics, Linköping University, Campus Norrköping, Advanced Optical Materials 2018. DOI 10.1002/adom.201701051

And the earlier article published in Nano Letters

Contact

More news from LOE

Person in labcoat and gloves pours a blue liquid onto a glass surface.

New sustainable method for creating organic semiconductors

Researchers at LiU have developed a new, more environmentally friendly way to create conductive inks for use in organic electronics. The findings pave the way for future sustainable technology.

Two researchers connect a beaker of water to some wires.

Electronic “soil” enhances crop growth

Barley seedlings grow on average 50% more when their root system is stimulated electrically through a new cultivation substrate.  LiU-researchers have developed an electrically conductive “soil” for hydroponics.

Crecent-shaped aerogel with water droplets.

Aerogel can become the key to future terahertz technologies

Researchers at LiU have shown that the transmission of terahertz light through an aerogel made of cellulose and a conducting polymer can be tuned. This is an important step to unlock more applications for terahertz waves.

Latest news from LiU

Professor Mattias Lindahl is contributing to a global ISO standard

There are hundreds of definitions of circular economy in the world, which leads to confusion. A new ISO standard with a definition widely accepted and disseminated will remedy the situation.

Tre persons in lab coates.

Better neutron mirrors can reveal the inner secrets of matter

An improved neutron mirror has been developed by researchers at LiU by coating a silicon plate with extremely thin layers of iron and silicon mixed with boron carbide. It paves the way for better studies of materials.

Lonely child in silhouette.

Lack of guidelines on care for children subjected to sexual abuse

Only half of 34 surveyed European countries have national guidelines on how to provide health care and treatment to children who have been subjected to sexual abuse. This is shown in a study led by researchers at Barnafrid at Linköping University.