Defect-Induced Dipole Moment Change of Passivators for Improving the Performance of Perovskite Photovoltaics

Defect passivation is crucial for improving the performance and stability of perovskite solar cells (PSCs). However, this process influences the surface work function (SWF) of the perovskite, potentially causing an energy-level mismatch. Previous studies that relied solely on electrostatic potential (ESP) analysis of passivator dipole moments may not adequately describe the changes in SWF at the passivator-perovskite interface. Our results reveal that the interaction between the passivator and defects would lead to different SWF trends when the same passivator is applied to n-type and p-type perovskites. We designed a series of anions to repair the iodine vacancy (V_I) and found that charge transfer from the passivator to Pb²⁺ can induce significant dipole moment changes at the interface, thus enhancing the SWF of n-type perovskite (n-PSK). As a result, the conventional cell achieved the highest power conversion efficiency (PCE) of 24.69% and exhibited great stability under continuous illumination or under ambient conditions.