Asymmetric Lamellar Templating of the Perovskite/C ₆₀ Interface for Scalable Inverted Perovskite Photovoltaics

Scalable inverted perovskite solar cells require top interfaces that combine defect passivation with spatially uniform electron extraction as the device area increases. Low‐dimensional capping layers based on bulky spacer cations can suppress surface recombination, but poorly controlled molecular packing often introduces transport barriers and local interfacial heterogeneity. Here, we introduce indol‐3‐ylethylammonium iodide (Ind) as a π‐electron‐rich spacer cation for asymmetric lamellar templating at the perovskite/C 60 junction. The heteroatom‐polarized indole framework creates lateral electrostatic anisotropy within the aromatic plane, promoting face‐to‐face spacer association and aligning the lamellar interphase. The resulting π‐rich lamellar interphase suppresses interfacial recombination, preserves electron extraction, and improves spatial optoelectronic uniformity in large‐area devices. Ind‐based devices achieve a certified efficiency of 26.94% in small‐area cells and a certified module efficiency of 23.21% for a 25 cm 2 monolithic module. They further retain > 93% efficiency after 1000 h at 85°C and maintain 85% of their initial efficiency after 1800 h under continuous 1‐sun MPP tracking. These results identify lateral electrostatic anisotropy as a molecular design principle for scalable perovskite/C 60 top interfaces.