Composite Electrodes for Perovskite Solar Cells

Perovskite solar cells (PSCs) represent a leading next-generation photovoltaic technology, boasting high efficiency and low fabrication costs. However, their commercialization is hindered by operational stability challenges, in which the back electrode material plays a pivotal role. This review presents the conceptual design logic of composite electrodes and systematically summarizes recent advances in composite electrode architectures. We critically analyze two main strategies: the blocking strategy, utilizing interlayers (e.g., Bi, Cr, TCOs, ZrN_x), and the alloying strategy, employing high- and low-melting-point alloys to suppress ion migration and optimize energy-level alignment. The review further establishes a mechanistic framework that emphasizes gradual interfacial evolution and provides critical discussions on oxidation mechanisms, adhesion issues, and trade-offs in electrode design. As a comprehensive review on this critical yet underexplored topic, this work offers essential guidance and insightful perspectives for future electrode innovation in PSCs.