Molecular Engineering on Kinetics-Driven Self-Assembled Monolayers Working as Auxiliary Layers on Dielectrics in Organic Field-Effect Transistors

Self-assembled monolayers (SAMs) are a class of quasi-2D materials adhesive to the substrate by chemisorption. Due to their transparency, diversity, stability, sensitivity, selectivity, and great potential in surface passivation, SAMs have been extensively investigated and applied in various functional devices, particularly in organic field effect transistors (OFETs). Among all the processing methods, kinetic-driven spin-coating is frequently used for the SAM preparation due to its high efficiency and low cost. However, the importance of SAM quality and its relationship to device performance has not been studied in detail, hindering the new SAM development and device optimization. In this study, SAMs prepared by kinetic-driven spin-coating are carefully investigated in terms of their surface morphology, density, and regularity, and proposed a correlation model between chemical structure and SAM quality. Additionally, the prepared SAMs are utilized as auxiliary layers on dielectrics and analyzed their effects on OFET properties. Through these investigations, a sequential relationship is established between chemical structure, SAM quality, and device performance, which can provide efficient feedback for system optimization. Four SAMs with variant conjugated groups are prepared by kinetic-driven spin-coating. The quality of SAMs is carefully evaluated from three aspects: surface morphology, molecular density, and packing regularity. By utilizing these optimized SAMs as the dielectric surface layer in organic field-effect transistors (OFETs), a comprehensive relationship is established between the chemical structure, SAM quality, and device performance.image