Physical mechanisms and design strategies for high-efficiency back contact tunnel oxide passivating contact solar cells

Back contact-based tunnel oxide passivating contact (TBC) solar cells (SCs) represent one of the significant research focuses for future development in the photovoltaic industry, owing to their advantages of high-efficiency potential and compatibility with large-scale mass production lines. However, the current efficiency of TBC SCs has not yet reached the expected level due to a lack of clear understanding of the working mechanisms and high-efficiency technological pathways. Here, we clarify the physical mechanisms and propose detailed strategies for designing high-efficiency TBC SCs through a comprehensive simulation study. The simulation results indicate that high-efficiency TBC SCs require extended carrier lifetimes, improved front-surface passivation, and minimized interface recombination in the p-region. Additionally, we also point out that the optimized cell size should balance carrier transport and recombination losses. Specifically, for small-pitch devices, reducing the fill size ratio of the p-type contact proves advantageous, whereas for large-pitch devices, a relatively larger fill size ratio of the p-type contact region is required. Moreover, based on the current passivation contact quality and device integration level, an efficiency of up to 28% is anticipated. This study reveals the working mechanism of the device in detail, providing a reference for the preparation of high-efficiency TBC SCs.