Ever wonder why wasps are more numerous and active during the summer? It’s because their bodies absorb sunlight and convert it into energy. With this fact in mind, Israeli and UK scientists have begun studying hornets and wasps (namely the Oriental Hornet) to see whether new solar cells could take a bit of inspiration from nature’s design.
According to the research team, led by Dr. Marian Plotkin from Tel-Aviv University, wasps benefit from solar energy due to the array of grooves that adorn their exoskeleton – each one measuring 160 nanometers in height. Meanwhile, the yellow part of the wasp’s body is made from a cuticle material bearing a series of interlocking oval-shaped protrusions, each of which feature a pinhole-sized depression. The yellow color of the cuticle comes from the pigment xanthopterin, which has the ability to change light into electrical energy. But beyond their body, even the wasps’ eyes are able to absorb light that can be converted into energy.
Within each layer of the wasp’s exoskeleton are rod-like structures embedded in a protein matrix, made from chains of the polymer chitin. This structure keeps the solar beams trapped in the wasp’s body, allowing it to bounce between layers. Using the wasp as inspiration, the UK/Israeli team made a dye-sensitized solar cell, which used xanthopterin as a light-harvesting molecule. Unfortunately the solar cell, which works in a similar way to the Gratzel cell (albeit with a nature-inspired structure), has a conversion efficiency of about 0.335 percent. Yes, this is quite a low conversion rate when compared to other solar cells, but it could still give way to benefits for the solar industry in general.
You should expect to see an increased use of xanthopterin in the production of solar cells in the future. We knew wasps had a purpose!
+ Tel-Aviv University
Image © Matti Paavola