Laser‐doped solar cells exceeding 18% efficiency on large‐area commercial‐grade multicrystalline silicon substrates

Large-area multicrystalline silicon solar cells fabrication by laser doping is studied in this paper. The liquid dopant solution is sprayed onto the SiNx:H film to act as dopant source. Laser doping is performed to locally melt silicon substrates, and phosphorus dopant atoms are incorporated into the liquid silicon by liquid-phase diffusion to form a selective emitter. Light-induced plating is carried out for front side metallization. The influences of laser energy density and pulse overlap on electrical performance of large-area multicrystalline silicon solar cells are obtained. The laser energy density and pulse overlap are optimized in consideration of sufficient built-in voltage and small-scale laser-induced damage. The typical spectral response for large-area multicrystalline silicon solar cells by laser doping is presented. The typical efficiency distribution for 1-day production of the 10 MW production line shows the overall average efficiency above 18% on large-area commercial-grade multicrystalline silicon substrates for the 4 months of operation, confirming the potential for transferring high-efficiency selective emitter silicon solar cells by laser doping into a production line. Copyright © 2012 John Wiley & Sons, Ltd.