Enhancing the Efficience of Solar Cells

Enhancing the efficiency of solar cells is a project which is sponsored by the Department of Energy.  This process is achieved by improving the absorbance of sunlight.  CLT focused on surface texturing of multi-crystalline solar cells for enhanced absorptivity.  A pulsed laser beam with tailored temporal pulse shape is scanned with 15 m/s across the wafer surface placing more than 100,000 dimples per second in the surface of the solar cell.  Fast controls with 50ns loop time were developed to accurately synchronize the laser with the scanner.  A special beam splitter optic was also developed splitting the laser beam into 4 beams of equal intensity.  This allows 450,000 dimples per second.  Subsequent etching of the dimples results in light trapping features.  CLT also developed high rate drilling for emitter wrap through (EWT) cells together with a laser manufacturer resulting in >6,000 holes per second in 200 um wafers with only 18W of laser power -- a 3x productivity improvement.