Dual-Ligand Regulation of Homogeneous Cation-Anion Distribution Enables Efficient and Stable Perovskite Solar Cells.

Abstract

While amidine ligands are known to significantly enhance defect passivation in perovskite solar cells (PSCs), their role in modulating perovskite film homogeneity through coordinated control of cation-anion distributions remains unexplored. Herein, we demonstrate that a dual-ligand strategy utilizing pyridine-2-carboximidamide hydrochloride (PCH) and pyridine-2,6-dicarboximidamide dihydrochloride (PBD) achieves homogeneous cation-anion distributions, enabling high-performance PSCs. Incorporated into the precursor solutions, these dual-ligand additives distribute uniformly throughout the perovskite bulk. By simultaneously utilizing their pyridine and amidine groups to passivate Pb2⁺ and FA⁺ ions, as well as employing hydrogen bonding to stabilize I- ions, the uniformity of anions and cations within the film is enhanced. Vacuum flash-assisted solution-processed PSCs incorporating PBD-passivated films with optimized homogeneity achieved a PCE of 26.66% (certified 26.33%). Notably, these devices retained over 90% of their initial efficiency after 1100 h of continuous maximum power point tracking (MPPT) under operational conditions (60 °C, N2 atmosphere). This PCE value ranks among the highest reported to date for perovskite solar cells. Our findings highlight that achieving homogeneous cation-anion distribution is essential for designing effective passivators, thereby simultaneously advancing both the PCE and operational stability of PSCs.