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Highly nonlinear transport across single-molecule junctions via destructive quantum interference.

Julia E GreenwaldJoseph CameronNeil J FindlayTianren FuSuman GunasekaranPeter J SkabaraLatha Venkataraman
Published in: Nature nanotechnology (2020)
To rival the performance of modern integrated circuits, single-molecule devices must be designed to exhibit extremely nonlinear current-voltage (I-V) characteristics1-4. A common approach is to design molecular backbones where destructive quantum interference (QI) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) produces a nonlinear energy-dependent tunnelling probability near the electrode Fermi energy (EF)5-8. However, tuning such systems is not straightforward, as aligning the frontier orbitals to EF is hard to control9. Here, we instead create a molecular system where constructive QI between the HOMO and LUMO is suppressed and destructive QI between the HOMO and strongly coupled occupied orbitals of opposite phase is enhanced. We use a series of fluorene oligomers containing a central benzothiadiazole10 unit to demonstrate that this strategy can be used to create highly nonlinear single-molecule circuits. Notably, we are able to reproducibly modulate the conductance of a 6-nm molecule by a factor of more than 104.
Keyphrases
  • single molecule
  • atomic force microscopy
  • living cells
  • density functional theory
  • photodynamic therapy
  • quantum dots
  • solid state