Engineering Ligand Reactivity Enables High-Temperature Operation of Stable Perovskite Solar Cells

Perovskite solar cells consisting of interfacial two-dimensional/three-dimensional heterostructures that incorporate ammonium ligand intercalation have enabled rapid progress toward the goal of uniting performance with stability. However, as the field continues to seek ever-higher durability, additional tools that avoid progressive ligand intercalation are needed to minimize degradation at high temperatures. We use ammonium ligands that are nonreactive with the bulk of perovskites and investigate libraries varying ligand molecular structure systematically. We find that fluorinated aniliniums offer interfacial passivation and simultaneously minimize reactivity with perovskites. Using this approach, we report a certified quasi-steady-state power-conversion efficiency of 24.09% for inverted-structure PSCs. In an encapsulated device operating at 85 degrees Celsius and 50% relative humidity, we document a 1560-hour T85 at maximum power point under 1-sun illumination.<br/><br/>Manuscript accepted in <i>Science </i>2023