A descriptor-driven framework for SiNx:H in crystalline silicon solar cells: linking bonding configuration to device performance and reliability

Hydrogenated silicon nitride (SiN x :H) is a cornerstone material in crystalline silicon photovoltaics, simultaneously providing antireflection functionality and defect passivation. However, these roles are typically treated independently, limiting predictive optimization, particularly in advanced architectures such as TOPCon, bifacial, and silicon-based tandem solar cells. This review synthesizes the literature on plasma-enhanced chemical vapor deposited (PECVD) SiN x :H into a descriptor-driven framework that unifies deposition conditions, bonding configuration, material descriptors, and device performance. The reviewed literature indicates that key parameters, including refractive index, hydrogen bonding states, fixed charge density, and interface defect density originate from a common amorphous Si–N–H network and are intrinsically coupled. This coupling governs optical response, hydrogen-mediated passivation, and long-term stability, leading to unavoidable trade-offs under conventional single-parameter optimization. Drawing on reported hydrogen kinetics and bonding stability studies, this review identifies their central role in determining both initial device performance and reliability under thermal and environmental stress. Furthermore, the surveyed literature indicates that the function of SiN x :H evolves from a standalone coating in conventional cells to a system-integrated material in advanced device architectures. This review provides a physically grounded basis for multi-parameter optimization and highlights key design constraints for next-generation silicon solar cells, enabling improved efficiency and long-term stability.