Area-Selective Atomic Layer Deposition of AlO_x at the Buried Interface for High-Performance Perovskite Solar Cells

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 Ni⁴⁺ 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 cm² 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).