Anti-reflective Film Inspired By Moth's Eyes Improves Solar Cells

Shiny new solar cells... not a good thing when the point is to capture every last ray of sunshine. In an effort to find the least reflective surface possible, scientists have looked to an unlikely source: the compound eyes of night-flying moths.

These nocturnal insects not only need to see well at night, they also must avoid attracting the attention of predators. Having one of the latter swoop in and say “My, what bright shiny eyes you have!” just ain't gonna cut it. Tens of millions of years of evolution has resulted in moth's eyes being exceptionally unreflective. Now we know why: the surface of a moth's eye is covered in regularly arranged protrusions only about 100nm high, which drastically reduces the reflection of light.

Researchers led by Noboru Yamada, a scientist at Nagaoka University of Technology in Japan, along with colleagues at Mitsubishi Rayon Co. Ltd. and Tokyo Metropolitan University have managed to produce a film modeled after the microstructure of moth's eyes. The reflectance of this film is under 0.1% and light transmission is an astounding 99.6%. An added benefit is that the film is water repellent.

Use of the new film, which can now be mass-produced, will increase the efficiency of solar cells by around 5%. "People may think this improvement is very small,” states Yamada, “but the efficiency of photovoltaics is just like fuel consumption rates of road vehicles. Every little bit helps.”

Other possible uses for the new film are as an anti-reflection coating on windows, computer displays and TV screens. Mothra, are you ready for your closeup now? (via R&D, OSA, and TechOn! - and thanks to Lady Bee for the tip!)