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 ≈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. Latest investigation of laser interaction on passivated contact devices such as TOPCon, to form nickel/copper plated contacts, reveal interesting findings. With optimized wavelength and pulse duration, damage from laser is kept highly superficial and is reversible by thermal annealing process. This allows reducing the polysilicon thickness, thereby decreasing production costs and also enables an efficiency gain of 1% (absolute).