The next wave of solar cells might be green… literally. Quantum mechanics is helping to make better solar cells – and may give us another perspective on why plants are green in the process.
A big problem in solar power is that sunlight is not constant: because of seasonal changes, night-time and clouds, the amount of sunlight that reaches panels is constantly shifting. This means we must regulate the power from the cells so that the grid doesn’t fry on sunny days and the lights don’t flicker as clouds pass. Trouble is, this dents the efficiency of the panels.
This is a potential issue for plants, too. Unlike solar cells, plants can regulate light levels by dissipating some solar energy as heat. But it turns out that plants’ green colour may also play a role.
Nathan Gabor at the University of California, Riverside, stumbled on this idea by chance. “I was sitting at this seminar, and I thought to myself ‘physicists are often credited with explaining why the sky is blue’,” he says. “So I thought, ‘well, why are plants green?’ ”
Gabor found that, while there are many hypotheses, none have been definitively proven. “The evolutionary evidence has several missing links along the way,” he says. So, when he and his team designed a solar cell that would efficiently regulate its power intake and output, they were surprised to find a potential answer.
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