A Hybrid Acceptor‐Modulation Strategy: Fluorinated Triple‐Acceptor Architecture for Significant Enhancement of Electron Transport in High‐Performance Unipolar n‐Type Organic Transistors

Abstract The development of unipolar n‐type semiconducting polymers with electron mobility (µ_e) over 5 cm² V⁻¹ s⁻¹ remains a massive challenge in organic semiconductors. Diketopyrrolopyrrole (DPP) has proven to be a successful unit for high‐performance p‐type and ambipolar polymers. However, DPP's moderate electron‐accepting capability leads to the shallow frontier molecular orbital (FMO) levels of the resultant polymers and hence limit the µ_e in unipolar n‐type organic transistors. Herein, this issue has been addressed by using a hybrid acceptor‐modulation strategy based on DPP‐containing “fluorinated triple‐acceptor architecture”, namely DPP‐difluorobenzothiadiazole‐DPP (DFB). Compared with DFB's non‐fluorinated counterpart, DFB features deeper FMO levels and a shape‐persistent framework. Therefore, a series of DFB‐based polymers demonstrate planar backbones and lowered FMO levels by ≈0.10 to 0.25 eV versus that of the control polymer. Intriguingly, all DFB‐polymers exhibit excellent unipolar n‐type transistor performances. Notably, a full‐locked backbone conformation and high crystallinity with crystalline coherence length of 524 Å are observed for pDFB‐TF, accounting for its high µ_e of 5.04 cm² V⁻¹ s⁻¹, which is the highest µ_e value for DPP‐based unipolar n‐type polymers reported to date. This work demonstrates that the strategy of “fluorinated triple‐acceptor architecture” opens a new path towards high‐performance unipolar n‐type semiconducting polymers.