One of the problems plaguing solar cells is their inability to absorb all of the light they receive. Currently, the bluish anti-reflective coating you see on most cells is 60 or 65 percent efficient, meaning nearly a third of the light is bounced back into the sky. That’s because the coating is only able to absorb a narrow range of wavelengths from the sun’s rays. Now, however, researchers at the University of Florida and Portland State University think they may have found a better way and their inspiration comes from an unlikely source: moth eyes.
A compound moth eye [left] is made up of thousands of ommatidia, which work like tiny cameras. Each is made up of a primitive cornea and lens (like our eyes) and a cluster of photoreceptor cells that tell light from dark and some measure of color. The compound eyes of moths are structured such that they are exceptionally anti-reflective—likely an evolutionary development to protect them from nocturnal predators.
What the researchers have discovered is that they can mimic those patterns by applying nanoparticles in a liquid suspension to a spinning silicon wafer. Bin Jiang, at Portland State University, describes the process as akin to putting “glass beads in a box and then shak[ing] it. All the beads arrange themselves into an array pattern.”
The process results in a coating with less than two percent reflection. The kicker? It’s also cheaper and simpler to produce than the standard (inefficient) blue coating. The team hopes soon to put the technology to work through a start-up company.