Unraveling Mixed‐Defect Transformations and Passivation Dynamics in Silicon Heterojunction Solar Cells

Abstract Defects in materials coexist in multiple forms, undergo dynamic transformations, and influence material properties. However, there is no comprehensive understanding of these dynamic transformations, which limits advances in defect‐state control. Conventional characterization methods focus on macroscopic properties but fail to resolve defect‐specific contributions to material functionality. Additionally, metrology typically quantifies defect concentration but neglects defect quality, oversimplifying defects as “more” or “less” while overlooking the impact of defect quality on material properties. Herein, the dynamic transformations of passivation‐related defects in silicon heterojunctions (SHJs) are examined through the decomposition of dual‐phase capacitance transients ( C ( t )). The C ( t ) response of the SHJs exhibits dual‐phase characteristics, revealing two distinct passivation‐related defect configurations. The results indicate that the passivation quality depends not only on the defect concentration but also on the defect bonding configurations. These configurations evolve into deeper‐ or shallower‐level defects depending on the deposition conditions, layer stacking sequences, and thermal annealing, ultimately impacting the overall material properties. This study links defect transformations to passivation quality, clarifying defect control in semiconductor devices. Broader applications of dual‐phase C ( t ) decomposition—including perovskite and tandem solar cells, light‐emitting diodes, photodetectors, and metal‐oxide–semiconductor devices—are also outlined, underscoring the potential of this technique for device performance enhancement.