Homogeneous Dip-Coating of Ion-Modulated Self-Assembled Monolayers for Large-Area Perovskite Photovoltaics
Self-assembled monolayers (SAMs) are effective hole-selective contacts for inverted perovskite solar cells, but scalable deposition on rough substrates is hindered by molecular aggregation, disordered packing, and incomplete adsorption. We propose a hybrid strategy incorporating 4-(Piperidin-4-yl)butanoic acid hydrochloride (PBACl) into the 4PABCz solution during dip-coating. PBACl suppresses aggregation via hydrogen bonding and ionic interactions, yielding homogeneous coverage and improved wettability. The piperidine and carboxyl groups passivate buried interfacial defects through hydrogen bonding and coordination with perovskites. Small-area cells achieve a champion power conversion efficiency (PCE) of 26.09%, while a 5 cm × 5 cm mini-module (aperture area 14.4 cm²) delivers 23.29% PCE. Encapsulated devices retain 80% of initial PCE after 1350 h maximum power point tracking under continuous illumination. This ion modulation strategy bridges molecular-level interface control with scalable processing, offering a pathway to industrially relevant perovskite photovoltaics.