Nitrogen‐Incorporated Silicon Dioxide Interlayer Enables Pinhole‐Reduced and Robust TOPCon With a High Implied Open‐Circuit Voltage over 760 mV

ABSTRACT Tunnel oxide passivating contact (TOPCon) technology has emerged as an industrial cornerstone for high‐efficiency crystalline silicon (c‐Si) solar cells. However, its passivation performance remains constrained by the thermal fragility of the ultrathin silicon dioxide (SiO x ) interface and the resulting formation of pinholes. Here, we report a nitrogen (N)‐incorporated TOPCon structure in which nitrogen (N) atoms are in situ doped into amorphous silicon via plasma‐enhanced chemical vapor deposition (PECVD) and are driven to the SiO x during annealing to form a robust SiO x N y interlayer. First‐principles calculations reveal that SiO x N y exhibits significantly enhanced bonding strength and superior thermal stability. Finite element simulations further show that SiO x N y possesses a thermal expansion coefficient better matched to both c‐Si and poly‐Si, suppressing stress concentration, preventing interface fracture, and reducing pinhole density. This atomic‐scale modification enables record‐breaking passivation performance, achieving an implied open‐circuit voltage of 760 mV and a low single‐sided recombination current density of 0.35 fA/cm 2 . Device simulations predict that the efficiencies of various TOPCon‐based cells can be significantly enhanced with minimal additional cost. Experimental data demonstrate that front‐junction TOPCon cells can achieve an efficiency improvement of 0.2%. This simple and industry‐compatible interface‐engineering strategy provides a highly scalable pathway for boosting TOPCon and back‐contact TOPCon solar cells’ performances.