The U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) has expanded Natcore Technology Inc.'s original license by adding new patents, under which Natcore will develop and commercialize a line of black-silicon products for solar cells.
Natcore's anti-reflective coating process begins with an uncoated, textured silicon wafer. First, nanoscale pores are etched into the wafer surface, using gold or silver nanoparticles, by submerging the wafer for a few minutes in a liquid solution at room temperature.
Next, using the company's liquid phase deposition process, Natcore scientists fill the pores and then over-coat them with silicon dioxide. This combination step both coats and passivates, thereby allowing lower reflectance, the company explains.
NREL says its most meaningful new black-silicon patent relates to the use of copper nanoparticles in the etching process instead of nanoparticles of gold or silver.
"Because copper is less expensive than the precious metals, this new patent could enable Natcore to further reduce the cost of solar cells," explains Chuck Provini, Natcore’s president and CEO. "This could be another step toward our goal of halving the cost and increasing the output of solar cells."
Natcore scientists have created a black surface on a silicon wafer with an average reflectance in the visible and near-infrared region of the solar spectrum of 0.3%, which Natcore says makes it the "blackest" silicon solar cell surface ever recorded.
The original NREL-Natcore license was granted in December 2011. Natcore and NREL have also entered into a cooperative research and development agreement to develop commercial prototypes that embody NREL's black-silicon inventions.