Achieving Excellent Surface Passivation with J_0,s Less Than 0.5 fA cm^-2 Utilizing a Carbon-Incorporated Intrinsic...

Crystalline silicon solar cells are among the most efficient technologies in the photovoltaic industry, with their conversion efficiency being highly dependent on surface passivation. In this study, A carbon-incorporated intrinsic polysilicon layer is developed using plasma-enhanced chemical vapor deposition to form a tunnel oxide passivating contact (TOPCon)-like structure combined with silicon oxide. As a result, an implied open-circuit voltage (iV_oc) as high as 754 mV is achieved and a recombination current density as low as ≈0.3 fA cm^-2 for n-type lifetime wafers with a flat surface. Furthermore, the mechanism of the carbon atoms is elucidated, which indicates that the carbon atoms capture more H and increase the interfacial SiO_x integrity, thereby reducing defect state density to achieve excellent surface passivation. Additionally, carbon atoms effectively reduce the bulk Shockley-Read-Hall recombination to improve the film passivation. Consequently, this passivation technology is applied to back-junction TOPCon cells to reduce the coverage of the rear p-type TOPCon, achieving an improvement in iV_oc of 10 mV, with a 0.2% absolute increase in efficiency predicted by numerical simulations. Moreover, this passivation technology can also be applied to back-contact TOPCon cells, along with various scenarios requiring high passivation, presenting significant potential for application and widespread popularization.