TOPCon shingle solar cells: Thermal laser separation and passivated edge technology

This work shows the first demonstration of thermal laser separation (TLS) and post-metallization passivated edge technology (PET) applied to tunnel-oxide passivated contact (TOPCon) shingle solar cells. The shingle solar cells with 26.46 mm x 158.75 mm size are separated from industrial full-square TOPCon host solar cells. The singulation is performed either by TLS from the front side (emitter side) or by conventional laser scribe and mechanical cleaving (LSMC) from the rear side (emitter-free side). The TLS optimized in this work yields up to 0.2%(abs) more efficient shingle cells after separation in comparison with LSMC-separated shingle cells. The most promising PET sequence identified for the singulated TOPCon cells consists of depositing an 8-nm-thin aluminum oxide layer by thermal atomic layer deposition at a temperature below 200 degrees C in conjunction with subsequent hotplate annealing at 250 degrees C. Application of the PET yields a boost of up to 0.5%(abs) in energy conversion efficiency for edge-passivated TOPCon shingle cells in comparison with their performance directly after separation. This efficiency-increasing impact of the PET sequence is found not to be strongly dependent on the separation process applied. The most efficient TOPCon shingle cell after PET achieves an efficiency of 22.0% and has been singulated by TLS.