Dimeric Giant Molecule Acceptors Featuring N‐type Linker: Enhancing Intramolecular Coupling for High‐Performance Polymer Solar Cells

Giant molecular acceptors (GMAs) are typically designed through the conjugated linking of individual small molecule acceptors (SMAs). This design imparts an extended molecular size, elevating the glass transition temperature (Tg) relative to their SMA counterparts. Consequently, it effectively suppresses the thermodynamic relaxation of the acceptor component when blended with polymer donors to construct stable polymer solar cells (PSCs). Different from previous reports utilizing p‐type linkers, here, we explore an n‐type linker, to dimerize the SMA units via a click‐like Knoevenagel condensation, affording BT‐DL. In comparison with B‐DL with a benzene linkage, BT‐DL exhibits significantly stronger intermolecular super‐exchange coupling, a desirable property for the acceptor component. Furthermore, BT‐DL demonstrates a higher film absorption coefficient, redshifted absorption, larger crystalline coherence, and higher electron mobility. These inherent advantages of BT‐DL translate into a higher power conversion efficiency of 18.49% in PSCs, a substantial improvement over the 9.17% efficiency observed in corresponding devices with B‐DL as the acceptor. Notably, the BT‐DL based device exhibits exceptional stability, retaining over 90% of its initial efficiency even after enduring 1000 hours of thermal stress at 90 °C. This work highlight their potential advantage of n‐type linker‐dimerized GMAs in enhancing intermolecular coupling for more efficient and durable devices.