Breaking the Mobility Barrier of Fully Non‐Fused‐Ring Electron Acceptors via an A‐D‐A'‐D‐A Framework with Noncovalent Conformational Locks

Fully non-fused-ring electron acceptors (FNEAs) represent a highly promising, cost-effective alternative to fused-ring acceptors for organic solar cells, owing to their structural simplicity and excellent solution processability. However, their practical application remains limited by inferior electron mobility compared to their fused-ring counterparts. In this work, we propose a universal A-D-A'-D-A framework that incorporates nitrogen heterocyclic cores and tailored π-bridges to overcome this fundamental bottleneck. This design exploits noncovalent conformational locking to rigidify the flexible single bond backbone, enabling a nearly planar and highly rigid molecular conformation without resorting to complex fused-ring synthesis. Theoretical calculations reveal that this structural rigidification significantly enhances electron delocalization, optimizes energy levels, and reduces exciton binding energy. Consequently, the designed A-D-A'-D-A acceptors, particularly 2O-BT-based 2N-12 and 4N-12, exhibit superior electron affinity and approximately 1.4-fold enhanced light absorption relative to the benchmark TBT-26. Most notably, they achieve record-high electron mobilities of 5.53 × 10⁻⁴ and 4.97 × 10⁻⁴ cm² V⁻¹ s⁻¹, representing a five fold improvement over state-of-the-art A-D-A type FNEA TBT-26 and even surpassing classical fused-ring acceptor ITIC. This work establishes a new FNEAs design, proving that structural simplification need not compromise charge transport performance, and outlines a clear pathway toward commercial organic photovoltaics.