Interface-Triggered Bulk Electrical Coupling in SnO₂ via Mesoscopic Chemical Reconfiguration for Scalable, High-Efficiency Perovskite Photovoltaics.

Abstract

The efficiency and stability of n-i-p PSCs are often hindered by energy losses and defect-induced interfacial failure, fundamentally stemming from mesoscopic surface chemical mismatch in SnO₂ nanocrystals. Herein, we propose a surface reconstruction strategy utilizing in situ generated [Al(OH)₄]^- ions to rebuild the surface electrical double layer. This approach not only yields monodisperse, highly stable SnO₂ colloids but also synergistically passivates deep-level defects arising from hydroxyl groups and oxygen vacancy clusters. The resulting amorphous Sn-AlO_x layer induces a surface electrostatic potential, significantly enhancing electrical coupling within the ETL bulk and establishing a robust carrier transport pathway. Consequently, we achieved champion efficiencies of 26.70% (certified 26.64%) for small-area cells and 24.56% (certified 24.22%) for mini-modules (21.50 cm²). Notably, fully blade-coated large-area modules (65 cm²) reached a high efficiency of 21.91%. By eliminating reactive sites at the buried interface, the unencapsulated devices retained 93% of their initial efficiency after 1100 h of MPPT (ISOS-L-2) and demonstrated a T₉₀ lifetime exceeding 700 h at 85°C (ISOS-D-2). This study provides novel insights for the large-scale production application of SnO₂ sol-gel in n-i-p perovskite solar modules.