Molecular electronic devices offer a path to the miniaturization of electronic circuits and could potentially facilitate novel functionalities that can be embedded into the molecular structure. Given their nanoscale dimensions, device properties are strongly influenced by quantum effects, yet many of these phenomena have been largely overlooked. We investigated the mechanism responsible for current rectification in molecular diodes and found that efficient rectification is achieved by enhancing the Stark effect strength and enabling a large number of molecules to participate in transport. These findings provided insights into the operation of molecular rectifiers and guided the development of high-performance devices via the design of molecules containing polarizable aromatic rings. Our results are consistent for different molecular structures and are expected to have broad applicability to all molecular devices by answering key questions related to charge transport mechanisms in such systems.
Keywords: Stark effect; charge injection; charge transport; molecular rectifiers; self-assembly.