Taking cues from the natural world, scientists at MIT have discovered a way to create solar cells that – like plants – can reliably draw on and convert sunlight into energy. Part of the challenge has been to address the destructive nature of long-term exposure to UV rays. But in order to work, solar panels need to be able to withstand the rigors of daily sunlight without significant degradation.
How is it that plants don’t shrivel up and die with regular UV light exposure?
Can we create solar cells that repair themselves?
MIT scientists have discovered a way to create solar cells that use the same strategy as plants to prevent degradation from solar exposure. In nature, the light-capturing molecules required for photosynthesis are continuously broken down and reassembled. This means that the cellular structures that absorb solar energy are always fresh and new.
Michael Strano, the Charles and Hilda Roddey Associate Professor of Chemical Engineering at MIT, and his team of graduate students and researchers have successfully replicated nature in a set of self-assembling molecules that can turn sunlight into electricity. By manipulating the level of solution in the lab, the molecules can be repeatedly broken down and then reassembled quickly.
Their paper on the work was published on Sept. 5 in Nature Chemistry.
According to Strano, the idea of replicating plant biology in solar cells occurred as he reflected on the fact that, during the height of the sun on a summer day, “a leaf on a tree is recycling its proteins about every 45 minutes, even though you might think of it as a static photocell.” Strano decided that attempting to translate nature’s repair mechanism to solar cells that can repair themselves could improve long-term performance and efficiency of solar panels.
The process of creating self-repairing solar cells is not easily summarized here (you can read the entire summary of the discovery and process at the MIT Press Release). We can say that it involves carbon nanotubes, phospholipids and five other compounds. Under proper conditions, the compounds will react to spontaneously assemble themselves into a light-harvesting structure that produces an electric current.
The practical significance of this solar research is that efficiency can be improved over time. Degradation of solar cells can result in up to 90% drop in efficiency. But if solar cells can repair themselves, high efficiency can be maintained, which will both lower the cost of solar electricity and make this renewable resource more attractive.