Moth eyes may hold key to more efficient solar cells

Physorg.com is reporting on a new process from Peng Jiang, an assistant professor at the University of Florida that looks to the structure of moth eyes for increased solar cell efficiency. Jiang method increases the amount of sunlight absorbed by reducing the amount of sunlight reflected. Jiang says that the current “bluish anti-reflective coating you see on solar cells these days is not very efficient beyond a narrow range [of wavelengths].” Reflections start increasing when the wavelength falls below 500nm and above 800nm.

When Jiang and his team looked at moth eyes, which are not very reflective, they discovered that moth eyes have tiny orderly bumps on their corneas. The bumps are in an array that prevents reflections. Jiang uses a method called “spin coating” to create the same effect. Nanoparticles in a liquid suspension are placed on a silicon wafer. As the wafer is spun, the force distributes the nanoparticles in the liquid, and a “sort of mask” is created that’s used as a template to etch the nanoparticles onto the wafer.

Jiang says that the process is very easy to do technologically, and that it’s also inexpensive. Its use will create solar cells that have less than 2 percent reflection, which compares to the 35 to 40 percent reflection rate current seen. Jiang also says that his group is ready to take the next step and actually start manufacturing cells with this anti-reflection array.  ‘We think it is ready now,” he says. “We are close to a start-up company that could use this process to make solar cells.” And he also hopes to improve upon the design. “Right now, this is done with single crystalline silicon wafers. We hope to extend the technology to work on multi-crystalline silicon, which is where solar cell technology is moving in the future.”

Moth Eye anti-reflection array on solar cell
Silicon wafer with anti-reflection array, modelled after a moth eye. Credit: Peng Jiang

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