Direct Deposition of C₆₀-Free SnO_x Electron Contact on Perovskite Enables Efficient and Outdoor-Stable Inverted Solar...

Fullerene-free electron transport layers (ETLs) are highly attractive for lowering the cost and simplifying the fabrication of inverted perovskite photovoltaics, but directly depositing inorganic ETLs on perovskite remains challenging. Here, we develop a low-cost SnO_x-based ETL that can be blade-coated directly onto perovskite films without using C₆₀ or other fullerene-derivative interlayers. Solvent engineering with 1-hexanol prolongs the wet-film lifetime and improves SnO_x film formation, yielding a smooth and compact ETL, while yttrium doping optimizes the interfacial energetics and promotes efficient electron extraction. Consequently, the directly deposited C₆₀-free ETL enables small-area devices with a power conversion efficiency of 19.15% and an open-circuit voltage of 1.06 V. Importantly, this strategy is readily extended to 21 cm² monolithic modules, delivering a champion efficiency of 15.82% with a geometric fill factor of 97.27%. The encapsulated modules retain 91.03% of their initial efficiency after 1000 h of maximum power point tracking at 40 °C and 50% relative humidity and also demonstrate stable outdoor operation over 63 days. These results highlight a practical and scalable route toward low-cost, efficient, and stable C₆₀-free inverted perovskite solar modules.