Researchers at Rensselaer Polytechnic Institute in New York have developed a new antireflective coating that boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire solar spectrum from nearly any angle.
An untreated silicon solar cell only absorbs about two-thirds of sunlight falling on it. After a silicon surface was treated with the new nanoengineered coating, however, the material absorbed 96.21 percent of the sunlight. Not only is this huge gain in absorption consistent across the entire spectrum of sunlight, from UV to visible light and infrared, but it allows equal absorption of light falling on the surface from any angle.
Conventional solar panels mainly absorb light from a source directly in front of them – many industrial solar arrays are mechanized to slowly move throughout the day so that their panels are perfectly aligned with the sun’s position in the sky. The new process makes this unnecessary – a stationary solar panel treated with the coating would absorb 96.21 percent of sunlight regardless of the position of the sun in the sky.
“To get maximum efficiency when converting solar power into electricity, you want a solar panel that can absorb nearly every single photon of light, regardless of the sun’s position in the sky,” said Shawn-Yu Lin, professor of physics at Rensselaer who led the research project. “Our new antireflective coating makes this possible.”
Typical antireflective coatings are engineered to transmit light of one particular wavelength. Lin’s new coating stacks seven of these layers, each with a height of 50 nanometers to 100 nanometers, one on top of the other, in such a way that each layer enhances the antireflective properties of the layer below it. These additional layers also help to “bend” the flow of sunlight to an angle that augments the coating’s antireflective properties. This means that each layer not only transmits sunlight, it also helps to capture any light that may have otherwise been reflected off of the layers below it.