Laser structuring for back junction silicon solar cells

We demonstrate mask-free fabrication of a 22.0%-efficient crystalline Si solar cell by applying laser ablation of Si and by laser ablation of protective coatings. The bulk absorber material is a p-type float zone silicon wafer and the designated cell area is 4 cm(2). While the processing time of our laboratory-type of laser system is far too slow for industrial processing, we estimate on the basis of our experiments that laser processing of 12.5 x 12.5 cm(2)-sized solar cells in just a few seconds is feasible with commercially available equipment. Copyright (c) 2006 John Wiley & Sons, Ltd.