Over time, most solar cells degrade due to prolonged exposure to the sun's scathing rays and are rendered useless. But with a little inspiration from nature, researchers have now created a new solar material that regenerates its damaged energy-capturing packets on-demand.
A small prototype solar cell built from the self-healing material can continuously produce electricity for an entire week without losing any efficiency, the scientists report.
The team was inspired by plants in nature. The ingredients within a plant’s leaves that turn sunlight into energy aren't actually immune to the sun’s damage. Instead, the molecules do their job (pump out sugar), get destroyed, and in less than an hour they regenerate. This process happens over and over again – enabling the leaves to produce energy at the same efficiency as they did on day one of their operation.
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“Nature has figured out how to work with solar energy,” said study lead researcher Michael Strano, a professor at the Massachusetts Institute of Technology (MIT). "It makes a dynamic cell that can constantly repair itself."
Today’s solar materials, which range from the rigid-silicon panels found on rooftops to the flexible, organic kind that can be coated like paint onto surfaces, all degrade over time when exposed to sun and oxygen. The result of this damage is that the material’s ability to turn sunlight into electricity decreases over time.
Strano and his team have built what they call a “dynamic” solar cell. The light-capturing material is a mixture of several chemicals, including a photosensitive protein, a fatty substance called a phospholipid and carbon nanotubes .
The team found that when they added soapy liquid to the mix, the components of the material break apart and form a soupy solution. In this form, the material can’t produce electricity. However, when put into a special bag with tiny holes that only let the soapy molecules – called surfactants – leak out, the “disordered mess” turns into “a very structured, very ordered material” – one that can turn sunlight into electricity.
This process of adding and removing the surfactant can be repeated over and over again, allowing the mixture to constantly regenerate its electricity-producing structure.
There’s still a lot to do before this technology could be used in homes and buildings to produce electricity. For one, the initial efficiency — a measure of how much of the sun’s light the panel can convert into electricity – of the new system is much lower than today’s solar panels.
The researchers see this research as a “first step” in developing a solar cell capable of regeneration, Strano said.
Strano and his team detail their research online Sept. 5 in Nature Chemistry.
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