Bifunctional D-π-A Ligand Directs Self-Organized Interface Passivation for Efficient Perovskite Photovoltaics

Passivating engineering has emerged as one of the most important strategies for improving the performance and stability of perovskite solar cells (PSCs). However, most post-treatment or buried-in passivation approaches are depth-dependent, where separate agents target either bulk or interfacial defects, complicating film processing and limiting large-scale fabrication. Here, we report a bifunctional D-π-A passivating ligand, triphenylamine-furan-cyanoacrylic acid (TPA-FCA), which integrates a hydrophilic anchoring group with a bulky hydrophobic donor-π scaffold. Such bifunctional TPA-FCA self-organizes within the as-crystallized perovskite film, vertically segregating to both interfaces and simultaneously passivating the defects in the perovskite bulk and at adjacent interfaces. This characteristic enables TPA-FCA to suppress both nonradiative and charge-transport losses in the complete PSCs. Consequently, PSCs incorporating TPA-FCA deliver a champion efficiency of 26.56% (26.37% certified) together with remarkable operational stability. Under continuous maximum power point tracking at 65 °C (ISOS-L-2), the unencapsulated TPA-FCA device maintains 90% of its initial efficiency after 1400 h (T₉₀ = 1400 h). Further fabrication of large-area (30 cm × 30 cm) perovskite submodules demonstrates the passivation efficacy of the TPA-FCA, yielding a certified efficiency of 21.93%. This work provides fundamental insights into self-organized ligands and demonstrates an applicable molecular design strategy for high-performance, stable, and scalable perovskite photovoltaics.