An untreated silicon solar cell absorbs only 67.4 percent of sunlight shone upon it, and the remaining unharvested light is a major barrier hampering the widespread adoption of solar power. However, a silicon surface treated with a new reflective coating developed by researchers at Rensselaer absorbs 96.21 percent of sunlight. The nanoengineered coating also allows those panels to absorb the entire spectrum of sunlight from any angle, regardless of the sun's position in the sky. This breakthrough would enable a new generation of stationary, more cost-efficient solar arrays.
Typical antireflective coatings are engineered to transmit light of one particular wavelength. Rensselaer's coating stacks seven of these layers so 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. The layers have heights of 50 to 100 nm, and are made up of silicon dioxide and titanium dioxide nanorods positioned at an oblique angle. The new coating can be affixed to nearly any photovoltaic materials for use in solar cells.