Local edge passivation of laser-scribed cells for compensating cut losses

The present work explores the application of Direct Atomic Layer Processing (DALP®) using NANOFABRICATOR® tool from ATLANT 3D for local edge passivation of laser-scribed cells. Owing to the defects created at the edges by laser scribing, the carrier lifetime decreases significantly in these regions as defects act as recombination centers. To compensate and minimize these losses, a 50 nm blanket layer of TiO₂, using titanium iso-propoxide (TTIP) as precursor and water as co-reactant, was deposited locally using atomic layer deposition (ALD) around the edges, thereby covering the impacted areas. Since the precursor, tunnel oxide passivated contact (TOPCon), solar cells used here were without metallization, the cell parameters like lifetime, lifetime at maximum power point (V_mpp), implied open circuit voltage (iV_oc) and implied fill factor (iFF) are evaluated in this study. The device is probed using a Sinton WCT120-PL tool and MDP Mapper from Freiberg Instruments for lifetime characterization before and after passivation. Layer deposition followed by annealing lead to a significant improvement of 149 μs in lifetime and a gain of 8.6 mV in implied open circuit voltage (iV_oc).