Butterfly wings inspire ‘invisible’ solar technologies

Supported by a three-year EPSRC fellowship, the research aims to manufacture novel bio-inspired optics for integration into lightweight solar panel technologies through applying unique properties seen in the nanostructures of certain butterfly wings — specifically the cabbage white butterfly (Pieris brassicae) and glasswing butterfly (Greta-Oto).

Currently developing solar concentrators, such as magnifying lenses, can use cheap glass or plastic optics to concentrate sunlight onto photovoltaic panels. In its fellowship summary, the team highlighted that whilst these systems, called CPV systems, can reduce the amount of expensive, heavily mined photovoltaic material required whilst maintaining overall power output, they can also be cumbersome.

Due to this, the researchers believe that combining the disciplines of concentrator photovoltaics with the natural lightweight butterfly wing structures via biomimicry could result in solar energy technology with a tripled power-to-weight ratio when compared with current tech.

“The nanostructures of some butterfly wings achieve exceptional optical properties within very thin layers,” said principal investigator Dr Katie Shanks, a postdoctoral researcher at Exeter University’s Environment and Sustainability Institute.

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Explaining how these properties can be applied to future solar tech, Shanks explained that cabbage white butterflies have lightweight reflective wings (for reflective funnels and light trapping layers), glasswing butterflies have lightweight anti-reflective/transparent wings (for protective cover glasses and focusing lenses) and there are ultra-absorbent black butterfly wing scales (for increased light absorption at the final energy conversion stage).

“Imagine a solar panel that doesn’t look like a solar panel — instead, it’s one thin layer in a window, or a wall or an EV car panel,” Shanks added. “It can be transparent, luminescent or any colour you want, because we are manipulating light at a scale smaller than the light itself.”

Key challenges involved in the research will be finding the most cost effective and eco-friendly methods, which will likely be influenced by state-of-the-art materials still under development, Shanks noted. 

Exeter is working closely with partners at Loughborough and Swansea Universities in the UK, the University of Jaen in Spain, and Australia’s University of New South Wales in addition to various industrial partners in optics, coatings and PV manufacturing.

“Biomimicry optics have a range of properties and other discoveries are anticipated within natural nanostructures which will be useful for the industrial partners to explore for their own products,” Shanks said. 

“Ideally, this research will highlight one or more nanostructures and techniques worthy of commercialisation into the envisaged solar devices. This will need bigger funding at the end of this research even if successful prototyping is completed within the fellowship as planned.

“There are many steps between lab stage prototyping and full scale marketable products but due to the current UK climate emergency targets, there will be a push for this technology's development to commercial level in time for the 2035-2050 targets.”