Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Herein, an alternative approach of metallization on tunnel oxide passivated contacts (TOPCon) devices, through the method of localized laser ablation and nickel-copper plating, is presented. The method is demonstrated to be a viable and effective alternative, yielding better performance and results than the conventional screen-printed contacts. The laser ablation process, with a lower increase in recombination current as compared to screen printing, proves to be a far less damaging process than the latter. TOPCon solar cells, fabricated and compared using the two metallization approaches, show a substantial improvement in an absolute power efficiency of approximate to 1%. Due to the highly superficial nature of damage with the optimized laser parameters, it enables the reduction of the poly-Si layer thickness down to 70 nm in the TOPCon stack and also a high cell conversion efficiency of 22%. This allows for a substantial reduction in ownership costs of the final device without compromising on performance, making TOPCon cells with plated contacts an attractive technological upgrade for industrial-level production following the passivated emitter rear contact cell technology.