Multifunctional Universal Additive for Stable and Efficient Inverted Perovskite Solar Cells

Abstract The performance of perovskite solar cells has significantly improved over the years in part due to defect passivation in the bulk and at the interfaces. While many additive molecules have been reported in the literature, they are commonly applicable only to one particular perovskite composition. Here we investigate a multifunctional additive, 4‐amino‐5‐bromo nicotinic acid (ABrNA), for use in both methylammonium (MA)‐free perovskites with different Br content (bandgaps ranging from 1.53 to 1.73 eV) as well as MA‐containing perovskites. Significant performance improvements are obtained for all compositions, which can be attributed to the presence of multiple functional groups capable of modifying the crystallization of the perovskite as well as passivating defects. Exceptional features of ABrNA make it a promising universal passivator, which leads to a PCE increase from 23.9% to 25.0% for CsFAMA solar cells, and from 22.0% to 23.0% for MA‐free solar cells. The ABrNA passivated MA‐free devices also exhibit exceptional operational stability, with T 90 exceeding 1000 h under ISOS‐L‐1 testing conditions. In addition, significant performance improvement is observed with ABrNA for modules in both conventional and inverted device architectures, further confirming the universality of ABrNA additive.