Researchers at the California Institute of Technology (Caltech) and the Karlsruh Institute of Technology (KIT), in Germany, have developed a technique that improves the ability of photovoltaic cells to absorb sunlight. For this, they have been inspired by the wings of the black butterfly (Pachliopta aristolochiae), which inhabit South and Southeast Asia.
According to a study published in the latest issue of the journalScience Advances, the wings of these Lepidopterans are covered in micro- and nanostructured scales that harvest sunlight at a wide range of angles and wavelengths.
The scientists note that the finding will have applications to improve the light-gathering capabilities of thin-film solar cells, a technology where efficiencies are currently quite limited.
"The structural design of the wings of this butterfly - based on ridges and small holes - simultaneously provides good mechanical stability while harvesting light very efficiently," says Radwanul Siddique of Caltech, a lead author.
To gain a better understanding of the optical properties of the wing structure, Siddique and his colleagues created a 3D model of nanostructures based on microscopic images of the butterfly's wings and calculated their light absorption capacities.
They then designed thin photovoltaic absorbers made of silicon to mimic the structure of the butterfly wing. The results showed a 200% increase in the absorption integrated in the model made with nanoholes.
The researchers say that the design's absorption capacity can be further improved by optimizing its engraving profile, for example by using an inverted pyramid model rather than a cylindrical one.