Bi-layer in-situ phosphorus doped poly-Si films by PECVD for blistering-free high-efficiency industrial TOPCon solar cells

The passivating contact concept stands out as one of the most promising and industrially viable photovoltaic (PV) technologies. Further improving the quality of physical contact has become a focus of ongoing research. The film blistering issue has been identified as one of the major bottlenecks for the polysilicon (poly-Si) films deposited by the PECVD approach. In this study, we investigated how the in-situ phosphorus (P) doping level within the poly-Si films contributes to the occurrence of blistering. Our investigations into the film blistering mechanisms reveal that a high in-situ P-doping suppresses hydrogen release levels and reduces the accumulation of residual stress during annealing, which leads to the blistering-free appearance, especially observed in heavily P-doped poly-Si films. However, as excessive P-doping could weaken the interfacial passivation quality, we propose a bi-layer structure of P-doped poly-Si films which allows the doping profile to be tailored and maintain good quality passivating contacts. Based on the bi-layer structure, we fabricated industrial-sized tunnel oxide passivated contact (TOPCon) solar cells, which attained an average efficiency of 23.84%. Our work not only presents a promising strategy for improving the performance of passivating contacts via the PECVD approach but also underscores the significant potential for its widespread implementation in industrial TOPCon solar cell manufacturing.