Low-Loss Singulation of TOPCon Half Solar Cells by TLS and Al2O3 Edge Passivation

This work addresses the separation of tunnel-oxide passivated contact (TOPCon) host solar cells into half solar cells. It demonstrates the feasibility of achieving almost loss-free cell performance after edge passivation by the passivated edge technology (PET). It is shown that edge passivation with aluminum oxide (Al2O3) is also compatible with TOPCon solar cells that have been fabricated with Al-free Ag screen printing paste for the front side finger contacts applying laser-enhanced contact optimization (LECO). The half solar cells, with an edge length of 182 mm x 91 mm, are separated from industrial pseudo-square M10-format TOPCon host solar cells by thermal laser separation (TLS) from the front side. An optimized TLS process results in an efficiency loss of only slightly above 0.1%abs. A high-throughput prototype tool with a capacity of about 16,000 half solar cells per run is used for an Al2O3 layer deposition on the cut edges. Using optimized processes, the PET recovered approximately 85%rel of the cutting losses in pseudo fill factor by applying Al2O3 edge passivation and annealing. Thus, TLS in combination with high-throughput Al2O3 edge passivation is a viable approach for industrial fabrication of highly efficient TOPCon half solar cells, whether LECO and Al-free Ag pastes are applied or not.