Ligand Assisted Hydrogen Bonding: A Game-Changer in Lead Passivation and Stability in Perovskite Solar Cells.

Lead halide perovskite solar cells (PSCs) have demonstrated power conversion efficiencies comparable to silicon-based solar cells, yet their instability under environmental stressors, such as humidity, heat, and light, remains a significant barrier to commercialization. A primary cause of this instability is the uncoordinated lead ions (Pb), which accelerates the degradation of PSCs and pose environmental concerns due to potential lead leakage. Recently, the introduction of ligands into PSCs has shown promise in mitigating lead toxicity through effective passivation, primarily by forming hydrogen bonds (H-bonds) between functional groups of the ligands and the perovskite structure. In this minireview, we explore the critical role of H-bonds in stabilizing PSCs by enhancing the structural integrity of the perovskite layer and reducing lead leakage. Furthermore, we discuss the contribution of these ligands in defect passivation, hydrophobicity, self-encapsulation, cross-linking, and self-healing mechanisms. These insights will highlight the multi-functional capabilities of ligands in improving the long-term stability and durability of PSCs, offering pathways to address current challenges in their commercialization.