Periphery Fusion Strategy of a Carbazole‐Based Macrocycle toward Coplanar N‐Heterocycloarene for High‐Mobility Single‐Crystal Transistors

Abstract Designing (hetero)cycloarenes through the modifications of the π‐topology and molecular packing of organic semiconductors has recently garnered considerable attention. However, their applications as an organic active layer in field‐effect transistors are very limited, and the obtained hole carrier mobilities are less than 1 cm² V^‐1 s^‐1. In this work, a novel alkyl‐substituted coplanar N‐heterocycloarene (FM‐C4) containing four carbazole units is successfully synthesized in crystalline form. As compared to the corresponding single‐bond‐linked carbazole‐based macrocycle M‐C4, it is found that the periphery fusion strategy greatly changes the electronic structures, energy levels, photophysical properties, host–guest interactions with fullerenes, and molecular crystal stacking motifs. In particular, the fully fused N‐heterocycloarene FM‐C4 exhibits a herringbone packing structure with an unusual long‐range π−π overlap distance as low as 3.19 Å, whereas the single crystal of M‐C4 demonstrates no π−π interactions. As a consequence, FM‐C4 in single‐crystal transistors displays the highest hole mobility of 2.06 cm² V^‐1 s^‐1, significantly outperforming M‐C4 and all the reported (hetero)cycloarenes and suggesting the high potential of (hetero)cycloarenes for organic electronic applications.