Asymmetrically Functionalized Electron‐Deficient π‐Conjugated System for Printed Single‐Crystalline Organic Electronics

Abstract

Abstract Large‐area single‐crystalline thin films of n‐type organic semiconductors (OSCs) fabricated via solution‐processed techniques are urgently demanded for high‐end electronics. However, the lack of molecular designs that concomitantly offer excellent charge‐carrier transport, solution‐processability, and chemical/thermal robustness for n‐type OSCs limits the understanding of fundamental charge‐transport properties and impedes the realization of large‐area electronics. The benzo[de]isoquinolino[1,8‐gh]quinolinetetracarboxylic diimide (BQQDI) π‐electron system with phenethyl substituents (PhC2–BQQDI) demonstrates high electron mobility and robustness but its strong aggregation results in unsatisfactory solubility and solution‐processability. In this work, an asymmetric molecular design approach is reported that harnesses the favorable charge transport of PhC2–BQQDI, while introducing alkyl chains to improve the solubility and solution‐processability. An effective synthetic strategy is developed to obtain the target asymmetric BQQDI (PhC2–BQQDI–Cn). Interestingly, linear alkyl chains of PhC2–BQQDI–Cn (n = 5–7) exhibit an unusual molecular mimicry geometry with a gauche conformation and resilience to dynamic disorders. Asymmetric PhC2–BQQDI–C5 demonstrates excellent electron mobility and centimeter‐scale continuous single‐crystalline thin films, which are two orders of magnitude larger than that of PhC2–BQQDI, allowing for the investigation of electron transport anisotropy and applicable electronics.

Keywords

• asymmetric n‐type organic semiconductors
• large‐area single‐crystalline thin films
• molecular design
• nitrogen‐containing π‐electron systems
• organic field‐effect transistors