High temperature solar absorbers using titanium aluminium nitride stacks

What is it about?

We show that titanium aluminium nitride coatings can be continuously tuned from absorbing to reflecting by changing the Ti-Al ratio, are stable to over 900C, and design a stack that absorbs 92% of sunlight while radiating very little heat.

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Why is it important?

One way of converting sunlight into electricity is to first convert it to heat. For maximum efficiency this should absorb a lot of sunlight, operate at high temperature, and ideally not re-emit much heat. In technical terms, this needs a coating that is heat-stable, absorbs light wavelengths well but reflects infrared wavelengths. We have shown that titanium aluminium nitride stacks are very good for this because they can be continuously tuned from reflecting to absorbing, form solid coatings and are very heat stable.