Effect of high-temperature wettability of glass on interfacial contact quality during metallization of silver electrodes in solar cells

Abstract

The efficiency of tunnel oxide passivated contact (TOPCon) solar cells depends on achieving high-quality metallization, with glass frits playing a critical role in promoting effective metallization and establishing stable ohmic contact at the Ag-Si interface. This study primarily investigated the flowability and wettability of different glass frits at high temperatures by adjusting the composition of low-lead glass, and analyzed their impact on the contact quality and electronic transport properties at the silver-silicon interface. The results demonstrated that excessive addition of Bi₂O₃ can lead to over-wetting of the glass frit. Overly etching of glass frit could pose a risk of damaging the silicon substrate. Inadequate wettability can lead to uneven contact interfaces after sintering, which degrades the silver-silicon contact performance. However, appropriate adjustment of the content of Bi₂O₃ and TeO₂ can lower the glass transition temperature (T_g) of the glass frit, promoted the dissolution and flow of silver powder. It also improved the wettability of the glass frit on the substrate material at high temperatures, facilitating the formation of uniform and dense electrode grid. Moreover, it can prevented excessive aggregation of silver particles, promoted the formation of uniformly distributed nano-silver crystallites on the silicon emitter surface. This improved the silver-silicon contact quality, enable more efficient current transfer from the silicon substrate to the electrode. And ultimately improves the photoelectric conversion efficiency of the solar cell.