Beyond Silver: Comparative Performance Analysis of Alternative Metallization Strategies in Silicon Solar Cells

The photovoltaic industry’s reliance on silver (Ag) for silicon solar cell metallization faces critical challenges due to Ag scarcity, cost volatility, and sustainability concerns. This study systematically evaluates advanced metallization strategies to reduce or eliminate Ag usage while maintaining high-performance solar cell operation. We investigate fine-line printing, hybrid/core-shell architectures, and alternative materials such as copper (Cu), aluminum (Al), and nickel (Ni). Fine-line printing enables Ag finger widths as narrow as 10–15 µm, reducing front-side Ag consumption by up to 25% (9 mg/W) without compromising efficiency. However, sub-10 µm finger widths introduce printability challenges and increased series resistance. Hybrid and core-shell pastes, such as Cu-core/Ag-shell configurations, mitigate Cu’s oxidation and diffusion risks at low temperatures but face limitations in high-temperature processes (>750°C) required for TOPCon and IBC cells. To address this, Ag-doped Ni pastes (4% Ag) demonstrate a breakthrough, achieving power conversion efficiencies comparable to traditional Ag contacts while slashing Ag usage to <0.5 mg/Wp. In parallel, Cu-only pastes are explored for their ultra-low cost and high conductivity, yet require advanced barrier layers (e.g., Ni, Ti) to suppress Cu diffusion into silicon during high-temperature firing. Recent optimizations in rapid thermal annealing processes enable Cu paste stability at industrial scales, achieving efficiencies of ~22.5%. Meanwhile, Al-only pastes, while limited by higher contact resistance, show promise for rear-side metallization if used with Al/(boron doped)Si or Al/Ge alloy mixtures.