Interfacial Engineering Tuning Enables MXene Electrodes in Silicon Heterojunction Solar Cells

Abstract Crystalline silicon heterojunction (SHJ) solar cells offer exceptional efficiency but are limited by their reliance on costly low‐temperature silver pastes for metallization. The high price and supply instability of silver present significant challenges to terawatt‐scale photovoltaic deployment, prompting the need for cost‐effective, SHJ‐compatible electrode alternatives. Solution‐processable 2D transition metal carbides and nitrides (MXenes) have emerged as promising candidates, yet their adoption is hindered by poor interfacial compatibility and oxidation susceptibility. Here, these challenges are addressed through a synergistic materials and interface engineering strategy. Amino acid‐functionalized MXenes enable tunable work function and significantly improve oxidation resistance, while maintaining high conductivity after 45 days in ambient conditions. Concurrently, a tailored hydrogen plasma pretreatment of the substrate effectively reduces interfacial contact resistance. The resulting SHJ solar cells with spray‐coated double‐sided MXene electrodes achieve a maximum efficiency of 24.96%, exceeding that of evaporated silver‐based counterparts. Furthermore, the unencapsulated devices retain over 90% of their initial efficiency after 200 days in ambient conditions. These results demonstrate the viability of MXenes as high‐performance, low‐cost electrodes and offer a practical route toward silver‐free silicon photovoltaics.