A Tricyclic Framework with Integrated B←N and Cyano Dual Functionalization for Superior n‐Type Organic Electronics

Abstract

n‐Type conjugated polymers featuring low‐lying lowest unoccupied molecular orbital (LUMO) energy levels are essential for achieving high‐performance n‐type organic thin‐film transistors (OTFTs) and organic thermoelectrics (OTEs). However, the synthesis of acceptors with strong electron‐withdrawing characteristics presents a significant challenge. Herein, a peripheral functionalization strategy is employed on the widely used tricyclic framework anthracene by introducing dual N,O‐bidentate BF2/B(CN)2 groups to enhance its electron‐withdrawing capability. This approach successfully navigates synthetic challenges, leading to the development of two novel acceptor building blocks: DBNF and DBNCN. Compared to the counterparts with a single N,O‐bidentate BF2/B(CN)2 moiety, DBNF and DBNCN exhibit an extended π‐backbone, enhanced molecular packing, and improved electron‐withdrawing properties. Utilizing these innovative acceptor monomers, copolymers, PDBNF and PDBNCN, are synthesized, which exhibit considerably suppressed LUMO ≈ –4.0 eV. The deep LUMO of PDBNF together with its favourable bimodal packing orientation leads to remarkable electron mobility of 3.04 cm² V⁻¹ s⁻¹ with improved stability in OTFTs. Importantly, efficient n‐doping in OTEs is achieved with PDBNCN, exhibiting exceptional conductivity of 95.5 S cm⁻¹ and a maximum power factor of 147.8 μW m⁻¹ K⁻²—among the highest reported for solution‐processed n‐type polymers.