Scalable Interface Engineering in Wide‐Bandgap Perovskite Solar Cells via Blade‐Coating Molecules with Promoted Parallel Orientation

Abstract Although interface engineering via organic molecules has enhanced the power conversion efficiency (PCE) of perovskite solar cells (PSCs), the spin‐coating method limits the thickness uniformity of the large‐area passivation layer. Herein, three multifunctional organic molecules with preferential parallel alignment, namely N‐Phenylthiourea (PTU), 1‐Benzylthiourea (BTU), and 2‐Phenylethylthiourea (PTTU), are blade‐coated on wide‐bandgap (1.68 eV) perovskite films to manage the surface defects. Density functional theory (DFT) calculations and experimental results reveal that extending the alkyl chain length can enhance the parallel orientation of molecules on the surface of the perovskite film, which means efficient interfacial charge extraction and better thickness uniformity. Among them, BTU with an optimal alkyl chain length produces the most effective synergistic modification. The corresponding PSCs achieve the champion PCE of 22.12% and 20.19% for active areas of 0.08875 and 1.0 cm 2 , respectively, marking one of the highest PCE for blade‐coated p‐i‐n PSCs (E g ≈ 1.68 eV). Besides, the BTU‐treated PSCs retained over 95% of the initial PCE after 1600 h without encapsulation. The uniformity of large‐area film (10 × 10 cm 2 ) and corresponding PSC performance validated the scalability of the design. This work provides a comprehensive strategy for designing multifunctional organic molecules to improve film uniformity and charge transport, which offers a promising pathway for high‐performance and large‐area PSCs.