Dual-Function Interface Engineering of SnO₂ Electron Transport Layers: Wettability Enhancement and Work Function...

The commercialization of perovskite solar cells (PSCs) requires scalable device architectures that integrate high efficiency with long-term stability. Here, we present a dual-function interface engineering strategy in which polyethyleneimine (PEI) is incorporated into SnO₂ to simultaneously enhance surface wettability and tune the work function. This dual control suppresses oxygen-vacancy defects, establishes interfacial dipoles, and optimizes energy-level alignment, thereby enabling efficient carrier extraction and uniform perovskite crystallization. Supported by advanced characterization techniques and density function theory calculations, PEI-modified SnO₂ ETLs yield PSCs with a power conversion efficiency of 24.49% and scalable minimodules (24.8 cm²) achieving 22.56% efficiency. The minimodules further exhibit excellent stability, retaining 94% of their initial performance after 500 h of operation. This solution-processable, ambient-compatible modification provides both mechanistic insight and practical viability, offering a robust pathway toward commercial-scale perovskite photovoltaics.