Nanoscale Surface Functionalization Based on Heterogeneous Self-Assembled Monolayers for Molecular-Scale Electronics

Mixed self-assembled monolayers (mixed SAMs)-based molecular-scale electronic devices in recent years have gained great achievement in the fundamental study on charge transport mechanism and electronic functionalities. This review aims to summarize the preparation and characterization, structure modulation, and applications of heterogeneous mixed SAMs in molecular electronics. One key advantage of SAM-based molecular devices compared to single molecular devices is the ability to tune the intermolecular interactions, and two-dimensional (2-D) assembly structure allows for the optimization of charge transport in desired devices. Herein we review the qualitative and quantitative examination of the nanoscale organization and intermolecular interactions of mixed SAMs obtained by various mixed SAM preparation and characterization techniques. The use of mixed SAMs to control the structural order and compactness of SAM to form high-performance molecular electronic devices is also reviewed. Finally, we wrap up the review by discussing the challenges of this technique for the development of novel electronic functional devices in the future.