Asymmetric Lamellar Templating of the Perovskite/C60 Interface for Scalable Inverted Perovskite Photovoltaics

Abstract

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/C60 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 25cm2 monolithic module. They further retain >93% efficiency after 1000h at 85°C and maintain 85% of their initial efficiency after 1800h under continuous 1-sun MPP tracking. These results identify lateral electrostatic anisotropy as a molecular design principle for scalable perovskite/C60 top interfaces. © 2026 The Author(s). Advanced Materials published by Wiley-VCH GmbH.