Topology‐Controlled Linear Tetramer Acceptors Enable Low Non‐Radiative Loss and Highly Ductile Organic Solar Cells

ABSTRACT Controlling the aggregation and mechanical compliance of non‐fullerene acceptors remains a key challenge for the development of high‐efficiency and mechanically robust organic solar cells (OSCs). Oligomeric acceptors offer an attractive strategy to bridge small molecules and polymers; however, most reported architectures adopt star‐shaped topologies that often suffer from steric congestion, limiting packing order and increasing non‐radiative recombination. Here, we report a topology‐regulated design strategy by constructing a linear‐extended tetramer (TY‐TAT). The linear architecture effectively enhanced the molar extinction coefficient (6.04 × 10 5 m− 1 cm − 1 ) and photoluminescence quantum yield to 2.93%. Consequently, quasiplanar heterojunction devices based on TY‐TAT exhibit a markedly reduced non‐radiative energy loss of 0.192 eV and an elevated open‐circuit voltage. Importantly, the incorporation of long flexible chains imparts excellent film ductility, delivering a crack‐onset strain of 42.5% in blend films without severely compromising molecular ordering. When employed as a guest acceptor in a D18/BTP‐eC9 ternary system, TY‐TAT regulates host crystallization behavior and enables a high‐power conversion efficiency of 20.31% with improved device stability. This work demonstrates that linear topology engineering of oligomeric acceptors provides an effective strategy to simultaneously modulate aggregation, suppress non‐radiative losses, and enhance mechanical robustness, offering new design guidelines for next‐generation high‐performance organic photovoltaics.