Molecular coordination-driven interfacial engineering for high-efficiency CsPbI3 perovskite solar cells

The intrinsic defects of CsPbI3 significantly degrade the photovoltaic performance of perovskite solar cells. Herein, a multifunctional interfacial modification strategy was developed using the nitrogen-rich heterocyclic molecule 2-hydrazinopyridine (2-HP). The nitrogen atoms of pyridine and hydrazine (-NH-NH2) as active sites can effectively drive coordination with unsaturated Pb2+ ions by Lewis acid–base interaction and anchor iodine-related defects by forming hydrogen bond. This synergistic defect passivation strategy reduced trap-state density and suppressed the defect-induced charge recombination loss. Consequently, the optimal 2-HP-modified CsPbI3 devices achieved a champion power conversion efficiency of 19.08%, corresponding to a 12% enhancement over their unmodified counterparts. This study establishes a practical molecular coordination-driven interfacial engineering approach for realizing high-performance all-inorganic perovskite photovoltaics.