Abstract
Highly nonlinear current-voltage (I-V) characteristics in single-molecule junctions based on destructive quantum interference (DQI) effects are key to realizing bias-controlled molecular switches. Using first-principles quantum transport calculations, we investigated the charge transport properties of 1,4-diphenyl-2,3-dioxa-7-tellurabicyclo(DPDT) coupled to gold electrodes via cyanide (-CN), isocyanide (-NC) and pyridyl (-PY) anchoring groups, respectively. We demonstrated that there are DQI effects between LUMO and LUMO+1 of the opposite phase in the three junctions. It was revealed that the p orbital of the tellurium atom can localize HOMO orbitals on central units of molecular systems, and weaken the amplitude of LUMO relative to LUMO+1. This eliminates the constructive quantum interference (CQI) between HOMO and LUMO, but enhances the DQI between LUMO and LUMO+1 near the Fermi energy level of gold electrodes (EF). As a result, the three molecular junctions dominated by two LUMOs exhibit extremely high nonlinear I-V characteristics, contributing to a current at a high bias (±0.8 V) >170 times larger than that at a low bias (±0.2 V). Our findings provide a potentially stable and low-loss bias switching in single-molecule junctions.
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