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

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.

Robust, high-performance n-type organic semiconductors.

Organic semiconductors (OSCs) are important active materials for the fabrication of next-generation organic-based electronics. However, the development of n-type OSCs lags behind that of p-type OSCs in terms of charge-carrier mobility and environmental stability. This is due to the absence of molecular designs that satisfy the requirements. The present study describes the design and synthesis of n-type OSCs based on challenging molecular features involving a π-electron core containing electronegative N atoms and substituents. The unique π-electron system simultaneously reinforces both electronic and structural interactions. The current n-type OSCs exhibit high electron mobilities with high reliability, atmospheric stability, and robustness against environmental and heat stresses and are superior to other existing n-type OSCs. This molecular design represents a rational strategy for the development of high-end organic-based electronics.