Molecular Rectifiers: A New Design Based on Asymmetric Anchoring Moieties

The quest for a molecular rectifier is among the major challenges of molecular electronics. We introduce three simple rules to design an efficient rectifying molecule and demonstrate its functioning at the theoretical level, relying on the NEGF-DFT technique. The design rules notably require both the introduction of asymmetric anchoring moieties and a decoupling bridge. They lead to a new rectification mechanism based on the compression and control of the HOMO/LUMO gap by the electrode Fermi levels, arising from a pinning effect. Significant rectification ratios up to 2 orders of magnitude are theoretically predicted as the mechanism opposes resonant to nonresonant tunneling.