Durable Defect Passivation of the Grain Surface in Perovskite Solar Cells with π‑Conjugated Sulfamic Acid Additives

Defect passivation has shown an essential role in improving the efficiency and stability of perovskite solar cells (PSCs). Herein, an efficient and low-cost π-conjugated sulfamic acid additive, 4-aminobenzenesulfonic acid (4-ABSA), is used to realize durable defect passivation of PSCs. The incorporation of 4-ABSA not only constructs a compact and smooth perovskite film but is also capable of passivating both negative- and positive-charged defects derived from under-coordinated lead and halogen ions. Besides, the π-conjugated system in 4-ABSA can induce preferred perovskite crystal orientation and stabilize the coordination effect between 4-ABSA and perovskite grains. As a result, the inverted planar PSC incorporated with 4-ABSA additives demonstrates an improved power conversion efficiency (PCE) from 18.25 to 20.32%. Moreover, this 4-ABSA passivation agent also enhances the stability of devices, which retains 83.5% of its initial efficiency under ambient condition at 60 °C after 27 days. This work provides a π-conjugated sulfamic acid for durable defect passivation of perovskite optoelectronic devices.