Bulk Organic Ions as Buried Interfacial Assembled Molecular Glues for Boosting the Performance of Perovskite Solar Cells

We employed a bulk organic ions HBTU, a multifunctional additive comprising O‐(benzothiazol‐1‐yl)‐N,N,N′,N′‐tetramethyldimethylammonium cation and PF 6 ‐ anions, in perovskite precursor solutions. Its benzotriazole and PF 6 ‐ groups coordinate with uncoordinated Pb 2+ to passivate lead vacancies, while tetramethylurea interacts with FAI via hydrogen bonding and steric effects, suppressing PbI 2 aggregation and delaying crystallization. The aromatic benzotriazole further enhances moisture resistance by forming hydrophobic grain‐boundary layers. HBTU distributes uniformly in the bulk and accumulates at the buried interface, forming a passivating molecular film. This dual passivation strategy yields perovskite solar cells with a champion power conversion efficiency (PCE) of 24.96% and exceptional stability, retaining 91.5% of initial efficiency after 1200 h in N 2 without encapsulation.