Dual-Site-Binding Ligand-Driven (100) Orientation for Efficient and Stable Perovskite Solar Cells

Regulating crystal orientation is a powerful strategy for enhancing the optoelectronic performance of perovskite solar cells (PSCs). However, most existing approaches rely on single-site ligand binding, which not only forms insulating layers that hinder charge transport but also involves weak coordination that limits orientation control. Here, we report a holistic strategy based on a dual-site-binding ligand, dithiopyr, that simultaneously modulates nucleation kinetics, crystal orientation, defect passivation, and charge transport in perovskite films. By coordinating its dual thioester functionalities with adjacent Pb²⁺ defect sites, dithiopyr effectively relieves lattice strain and promotes a preferential (100) orientation, thereby facilitating efficient charge transport. As a result, the inverted PSCs achieve power conversion efficiencies of 26.90% (certified 26.14%) (1.55 eV), 22.02% (1.25 eV), and 23.11% (1.68 eV), respectively. Notably, large-area modules (30 × 30 cm²) deliver an efficiency of 21.28%, which is among the highest values reported for inverted perovskite solar cells. Unencapsulated devices retain 93.1% of their initial efficiency after 3600 h under ambient conditions and maintain over 95% of their initial performance after 1100 h of maximum power point tracking. This work establishes dithiopyr as a versatile and robust platform for precise crystal orientation control toward high-performance perovskite photovoltaics.