Researchers at Northwestern University’s McCormick School of Engineering recently announced that they have developed a new material that absorbs a wide range of wavelengths and could lead to more efficient and less expensive solar technology.
A paper describing the findings, “Broadband polarization-independent resonant light absorption using ultra-thin plasmonic super absorbers,” was published recently in the journal Nature Communications, and it explains that solar cells are only as efficient as the amount of sunlight they collect. “The solar spectrum is not like a laser – it’s very broadband, starting with UV and going up to near-infrared,” said Koray Aydin, assistant professor of electrical engineering and computer science and the paper’s lead author. “To capture this light most efficiently, a solar cell needs to have a broadband response. This design allows us to achieve that.”
The Northwestern researchers used two unconventional materials – metal and silicon oxide – to create thin but complex, trapezoid-shaped metal gratings on the nanoscale that can trap a wider range of visible light. The use of these materials is unusual because on their own, they do not absorb light; however, they worked together on the nanoscale to achieve very high absorption rates.
So how do these findings relate to today’s solar applications? Well, here’s where it gets really complicated because this research is not directly applicable to solar cell technology. Metal and silicon oxide cannot convert light to electricity; in fact, the photons are converted to heat and that fact might allow novel ways to control the heat flow at the nanoscale. However, the innovative trapezoid shape could be replicated in semiconducting materials that could be used in solar cells. If applied to semiconducting materials, the technology could lead to thinner, lower-cost and more efficient solar cells.