Addressing Edge Recombination Losses in Shingle Cells by Holistic Optimization of the Process Sequence

This work focuses on edge recombination losses of cut silicon solar cells, with special attention to shingle cells. We discuss a high-throughput method to form emitter windows by laser ablation of the p/n-junction along the cut line. To show the proof of concept, we fabricate symmetrical test structures that reveal a superior surface passivation in the ablation areas. Further, we present results where emitter windows are implemented into our PERC baseline sequence by a single additional structuring step. Shingle cells with emitter window show 83 %rel less losses in pseudo fill factor pFF after thermal laser separation (TLS) compared to cells with full area emitter. Additionally, we introduce an enhancement of the passivated edge technology (PET) by optimizing of atomic layer deposition. We prepared lifetime samples and cut solar cells. We find an increased effective lifetime of the excited carriers by a factor of 1.75. The pFF gain for cut solar cells is increased by 24 %rel. In total, our work provides two methods that can save up to 80 % of the power losses in cell cutting by TLS, and the methods are feasible for integration into existing industrial process chains.