Simultaneously Achieved Defect Passivation and Crystallization Modulation by a Multifunctional Pseudohalogen Salt for Efficient and Stable Perovskite Solar Cells

Abstract

The accumulation of defects and ion migration at the surfaces and grain boundaries of perovskite impedes the improvement of performance and stability in perovskite solar cells. Therefore, developing strategies to reduce trap‐assisted nonradiative recombination and suppress ion migration in perovskite films is urgently needed. Herein, a multifunctional pseudohalogen salt additive, (benzotriazol‐1‐yloxy) dipyrrolidinocarbenium hexafluorophosphate (denoted as BDPF6), composed of a benzotriazole derivative cation and hexafluorophosphate anion, is incorporated into the perovskite precursor solution. The anion vacancies of perovskite films are filled by , whereas the cation and anion in BDPF6 form ionic and coordination bonds with the perovskites. The BDPF6 additive promotes the crystallization of perovskite films with large grain size, reducing defect densities, prolonging carrier lifetimes, and inhibiting ion migration. Thus, the power conversion efficiency (PCE) of the BDPF6‐modified device remarkably improves from 20.36% to 22.68%. The unencapsulated BDPF6‐modified device maintains 97% of its initial PCE after 1,400 h of exposure to an ambient environment with a relative humidity of 10–20%, whereas the control device maintains only 85% of its initial PCE. Similarly, the BDPF6‐modified device maintains 78% of its original PCE after aging at 60 °C for 1,400 h, whereas the control device only maintains 55%.