Nanomaterials that Split Sunlight Into Separate Colors
Could Bring Solar Panels to 50% Efficiency
© Pink Floyd
Couldn’t Resist the Pink Floyd Reference…
I don’t know about you, but I love to follow the progress of technology. Every year batteries improve so they can hold more power, LEDs become brighter, CPUs become faster, hard drives can hold more data, etc. And the beautiful thing is that most of these improvements usually end up being less expensive, or at least priced similarly, to the technologies they supplant. What’s not to like? One area where a lot of progress has been made over the past few decades is solar panels, yet there’s still a lot of headroom left to push things further. That’s exactly what a new DARPA-funded project is trying to do by using nanostructured materials to make solar panels much more efficient than they currently are (they claim they can get to above 50% efficiency, against the less than 20% which is the norm right now).
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The idea is clever: By decomposing sunlight into its constituents and aiming each of those are precisely tuned solar cells that are most efficient when absorbing that specific color, much higher levels of conversion efficiency can be possible. At least that’s the theory.
In the last several years scientists have gotten better at manipulating light at a very small scale, sorting it by color, trapping it, and guiding it from one spot to another using thin layers of material that incorporate tiny features that are often smaller than the wavelength of light. [...]
The challenge with this approach is that no one makes these precisely structured materials over the large areas and in the large volumes needed in the solar industry. But Atwater compares the device to a flat screen TV, which is itself a sophisticated device for manipulating light, with its millions of transistors for switching on and off different colored pixels.
So it seems like the problem here is more one of economies of scale than anything else, and that’s encouraging. Scaling up is a more predictable process than hoping for a technical breakthrough to happen. Even if it takes many years before these types of solar panels can be produced at competitive prices, if they reach anywhere close to their theoretical efficiency levels, they’ll change the world.