While most college students aren’t professionals yet, some are closer than others. According to MIT News, a pair of college students won a Materials Science and Engineering contest with a truly innovative solar design. Here’s an excerpt:
Biomimicry — known as “innovation inspired by nature” — has led to the invention of bullet trains, vaccines, adhesives, and light bulbs, among other things.
Add to that list the winning invention of last night’s MADMEC competition: Influenced by the anti-reflective wings of the glasswing butterfly, an MIT team created a low-cost coating for solar cells that mitigates reflection, allowing the cells to absorb nearly all light to boost efficiency.
For that invention, the two-student team, aptly named Glasswings, took home the grand prize of $10,000 from the ninth annual MADMEC contest, organized each year by MIT’s Department of Materials Science and Engineering (DMSE) and sponsored this year by Saint Gobain, and Dow Chemical…
Reflection is an issue for many optoelectronic devices, including photovoltaics, smartphone displays, and windows, Al-Obeidi said during his team’s presentation. Typical solar cells made of silicon, for instance, reflect up to 30 percent of light, reducing efficiency.
As a solution, manufacturers use anti-reflective coatings. But these coatings are expensive to produce and even still don’t absorb all light. “We asked the question, ‘How does nature solve these problems?’” Al-Obeidi said, “because nature usually has a pretty interesting solution.”
As it turns out, the transparent wings of the glasswing butterfly are coated with nanostructures that resemble tapered pillars on pedestals. These “nanopillar” structures act essentially as anti-reflective coatings, reflecting 2 to 5 percent of light from the butterfly’s wings.
The team reconstructed these tapered nanostructures in a coating, but kept the process simple, inexpensive, and scalable. To do so, they used common photovoltaic materials and fabrication tools. This involved depositing oxide on a glass film, applying a patterned mask of silver, and etching — removing layers from the surface, except those protected by the mask — with different gases.
But the trick was tweaking the etching gases during the process, which allowed them to customize the nanostructure shape. Essentially, they could shrink the diameter at the top of the structure and keep a thicker diameter at the base to create tapered nanopillars.
“That structure’s very unique, because it’s been shown by modeling that that has the best optical properties … which has to be structured by things that are more complicated than this simple technique,” Al-Obeidi said.
The coating is significantly less expensive and quicker than other anti-reflective coatings, Al-Obeidi said, and is economically viable for solar cells if the price point is less than $14 per square meter. The coating can also be used to reduce glare on glass and other displays.