Rapid reliability assessment and mechanistic insight of Cu@Ag-metallized SHJ solar cells under acetic acid vapor aging

Abstract

Low-temperature Ag-coated Cu (Cu@Ag) paste has been widely adopted as a standard electrode material for silicon heterojunction (SHJ) solar cells, driven primarily by escalating cost-reduction pressure and growing demands for manufacturing sustainability through reduced reliance on scarce silver resources. However, the long-term behavior of such metallization under damp-heat (DH) conditions requires closer examination, as acidic species from encapsulant hydrolysis could potentially affect electrode integrity. Herein, the degradation behavior of low-temperature Cu@Ag paste-metallized SHJ solar cells was investigated under accelerated acetic acid vapor aging, a cell-level method that enables rapid assessment of gridline corrosion resistance via accelerated corrosion attack. The results reveal that acetic acid vapor promotes preferential dissolution of the Cu core through localized galvanic microcells formed at Ag-shell defects. The released Cu 2+ reacts with acetate ions to form copper acetate products that disrupt gridline conductivity and increase resistive losses, thereby degrading cell performance. In contrast, the indium tin oxide (ITO) layer exhibited only a limited response, confirming that Cu@Ag gridline corrosion dominated the degradation pathway under the present conditions. Guided by these mechanistic insights, an optimized Cu@Ag paste featuring two synergistic enhancements, namely conductive powder architecture design and chemical inhibitor incorporation, was evaluated. Comparative experiments demonstrate that this optimized paste markedly suppresses gridline degradation and enhances the efficiency retention of SHJ solar cells compared with conventional counterparts. These findings provide valuable insights and methodological references for designing durable Cu@Ag pastes and enhancing SHJ module reliability in field applications.

The authors' abstract, as published at the source. Solar Energy Materials and Solar Cells, 2026 · DOI ↗