Ga Doping Enables (110) Facet Control and Surface Passivation of SnO₂ for Efficient and Stable Inverted Perovskite...

Perovskite solar cells (pero-SCs) with inverted (p-i-n) architecture have advanced rapidly, yet combining high efficiency with long-term operational stability remains challenging, mainly due to commonly used organic cathode buffer layer (CBL) (between C₆₀ electron transporting layer and metal cathode) such as bathocuproine (BCP) with photo-thermal instability. Here, Ga-doped SnO₂ (Ga:SnO₂) is introduced as an inorganic CBL to replace BCP. Mechanistically, Ga incorporation promotes the preferential growth of the (110) facet of SnO₂ nanoparticles, which markedly enhances electrical conductivity and electron mobility of the CBL. It further suppresses non-radiative recombination by passivating surface defects and reducing the interfacial trap density. The improved energy-level alignment at the interface facilitates efficient electron extraction. These synergistic effects-validated by a suite of characterizations-enable inverted pero-SCs with a champion power conversion efficiency of 27.06% (certified 26.77%) and robust stability, retaining 88% of initial efficiency after 1500 h of operation at 85°C. This work demonstrates a viable and scalable pathway to high-performance and long-term stable pero-SCs.