BN‐Acene Ladder with Enhanced Charge Transport for Organic Field‐Effect Transistors

Abstract The in‐depth research on the charge transport properties of BN‐embedded polycyclic aromatic hydrocarbons (BN‐PAHs) still lags far behind studies of their emitting properties. Herein, we report the successfully synthesis of novel ladder‐type BN‐PAHs ( BCNL1 and BCNL2 ) featuring a highly ordered BC 3 N 2 acene unit, achieved via a nitrogen‐directed tandem C−H borylation. Single‐crystal X‐ray diffraction analysis unambiguously revealed their unique and compact herringbone packing structures. Micro‐sized single‐crystalline organic field‐effect transistors (OFETs) demonstrated that an enhanced charge transport capability, with BCNL2 achieving a hole mobility of up to 0.62 cm 2 V −1 s −1 –three orders of magnitude higher than that of BCNL1 ( μ h max =6 × 10 −4 cm 2 V −1 s −1 ), ranking among the highest values for BN‐PAHs‐based OFETs. Detailed calculations attribute this significant enhancement in the hole mobility to the marked reduction in reorganization energy ( λ ) of BCNL2 , resulting from the five‐membered pyrrole ring annulation and molecular skeleton elongation. This work provides insight into molecular design principles for potential BN‐PAHs in optoelectronic applications.