26.31%-efficiency TOPCon solar cells enabled by synergistic metallization with reduced optical shading and contact resistance losses

Abstract

Although tunnel oxide passivated contact (TOPCon) solar cells have become dominant in the crystalline silicon photovoltaic market, conventional TOPCon metallization relies on Al-containing Ag pastes and high-temperature firing, causing severe passivation degradation and optical shading. To address this, this study proposes a synergistic metallization strategy combining Al-free Ag paste with a tailored laser-enhanced contact optimization (LECO) process. LECO enables an advanced, low-penetration Pb-Ag/Si contact configuration with low resistivity, eliminating Al-induced alloying. Simultaneously, the low-corrosivity, highly rheological Al-free paste preserves surface passivation and reduces shading, achieving a high gridline aspect ratio of 0.55 and an exceptional open-circuit voltage (Voc) gain of 10.2 mV. Notably, the enhanced spectral response boosts the short-circuit current density (Jsc) to a high value of 41.98 mA cm–2, representing the highest certified Jsc reported to date for large-area TOPCon solar cells and contributing to a high certified efficiency of 26.31%.