Specialists of the Karlsruhe Institute of Technology (Germany) managed to transfer the nanostructure of butterfly wings to solar cells, raising the theoretical limit of the light absorption coefficient by 200%.
Pic: RADWANUL H. SIDDIQUE, KIT/CALTECH
Sunlight, reflected from the smooth surface of solar cells, is wasted. Wings of Pachliopta aristolochiae butterfly , outwardly completely black, are covered with nano-holes that help absorb light. Scientists drew attention to these structures and decided to reproduce them in a layer of silicon covering a film thin as a solar cell.
Subsequent analysis of light absorption yielded promising results: compared to a smooth surface, the absorption coefficient perpendicular to the incident light increased by 97% and continued to increase gradually to 207% at an angle of incidence of 50 degrees.
“This is especially interesting for European conditions. Usually we have scattered light, which falls on solar cells at a vertical angle” says Hendrik Hölscher, head of the team of scientists.
However, this does not mean that the performance of photocells will also increase threefold, since other factors are important. 200% is the theoretical limit of efficiency, says Guillaume Gomart, one of the researchers.
Before transferring nanostructures to solar cells, the researchers determined the diameter and location of the nano-holes in the butterfly’s wing, scanning it with an electron microscope. They then analyzed the light absorption coefficient for various hole patterns by computer simulations and found that the most stable absorption coefficient gives an unordered arrangement of holes of different diameters. Such a structure they transferred to the photocell layer, the holes in which differed in diameter from 133 to 343 nm, reports EurekAlert.
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