Supramolecular Design and Assembly Engineering toward High-Performance Organic Field-Effect Transistors

Supramolecular assembly describes the dynamic processes in which molecules of a system organize themselves into ordered patterns or structures through noncovalent interactions. Among these systems, single-crystalline organic semiconductors (OSCs) in electronic devices, such as organic field-effect transistors (OFETs), represent a class of semiconductive molecules that can form regular lattices. These organic nature of these OSCs allows for precise design of the superstructure and compact arrangement through intermolecular interactions, such as [pi...pi], van der Waals, and polarity-polarity interactions. As a result, they exhibit exceptional carrier mobilities and stability in solid-state aggregations, making them ideal for electronics research and production. However, it is important to note that defects and disorders are unavoidable in spontaneous and rapid supramolecular assembly processes. They will hinder charge-carrier transport as scattering sites and thus impair device performance. On the other hand, by utilizing different processing methods, OSCs can be prepared into variant aggregated forms, such as amorphous, liquid-crystalline, or single-crystalline films. The performance of devices that use these materials relies heavily on the specific properties of the assembled components. Therefore, the regulation of supramolecular assembly in solid aggregations is necessary to achieve high-performance devices as well as scaled electronic production with controllable cost, particularly in emerging fields, such as flexible electronics, wearable devices, and low-cost sensors. Currently, researchers are actively exploring the fundamental mechanism to regulate and enhance the performance of OSC aggregations as well as developing novel materials that broaden their potential applications. However, investigation on mechanisms and functions pertaining to molecule-level arrangements in solid-state OSCs remains underdeveloped, necessitating in-depth investigation and summarization. In this Account, we first provide an overview and analysis of the supramolecular assembly process and the underlying mechanisms, focusing on three key dimensions, i.e., (i) molecular design, (ii) intermolecular interaction, and (iii) macroscopic morphology control. Then, we highlight our research on the morphology regulation and optimization of OSC films. Three strategies have been summarized and discussed to achieve high-quality OSCs and high-performance OFETs. These include: (i) molecular engineering of OSCs to install supramolecular assembly properties, (ii) thermal annealing optimization on OSCs films to increase crystallinity, and (iii) strain engineering processing on OSCs to install device functionalization. Their design rationales for target applications were analyzed. By deliberation on these issues, the fundamental underpinnings of material investigation are elucidated, thereby affording readers a comprehensive survey of the methodologies and strategies employed in the realm of single-crystalline semiconductors. To conclude, the main challenges and future perspectives toward the forthcoming development and commercialization of high-performance functional OFETs are discussed to inspire more novel material designs and regulation methodologies.