Area‐Selective Atomic Layer Deposition of AlO _x at the Buried Interface for High‐Performance Perovskite Solar Cells

ABSTRACT Self‐assembled monolayers (SAM) have demonstrated significant potential for enhancing the performance of perovskite solar cells (PSCs). However, their incomplete surface coverage exposes defect sites on the NiO x surface, leading to detrimental non‐radiative recombination and exacerbating the perovskite degradation. To overcome these limitations, we developed a strategy of area‐selective atomic layer deposition (AS‐ALD) that precisely deposits an ultrathin AlO x layer on exposed NiO x surfaces while preserving SAM‐covered areas. This approach effectively suppresses charge recombination by blocking direct contact between NiO x and the perovskite while leveraging the intrinsic negative fixed charges in AlO x to attract holes and repel electrons. Importantly, the SAM‐covered areas remain unaffected, ensuring unhindered carrier extraction. Additionally, the deposited AlO x reduces the deleterious Ni 4+ content, which can readily trigger perovskite decomposition, thereby significantly enhancing device performance and stability. As a result, the PCE of PSCs increased to 26.41%, with perovskite modules achieving 20.88% efficiency over a 64.68 cm 2 active area. Device stability significantly improved with ∼ 95% initial PCE retained after 1500 h dark storage (ISOS‐D‐1), ∼ 80% after 800 h at 85°C (ISOS‐D‐2), ∼ 85% after 48 thermal cycles (ISOS‐T‐1), and ∼ 90% after 1300 h continuous 1‐sun illumination (ISOS‐L‐1, MPPT).