Controlling destructive quantum interference in tunneling junctions comprising self-assembled monolayers via bond...

Area of Science:

• Molecular electronics
• Quantum phenomena in nanoscale systems

Background:

• Quantum interference (QI) effects significantly influence conductance in molecular tunneling junctions.
• Predicting and controlling QI features in nano-scale devices remains a challenge.

Purpose of the Study:

• To design and synthesize molecular wires to control quantum interference (QI) features.
• To experimentally separate the effects of bond topology and electronegativity on QI.

Main Methods:

• Synthesis of three benzodithiophenes based molecular wires (linear-conjugated, cross-conjugated, and cross-conjugated quinone).
• Fabrication of molecular junctions using eutectic Ga-In (EGaIn) and conducting polymer atomic force microscopy (CP-AFM).
• Utilized density functional theory (DFT) and transition voltage spectroscopy (TVS).

Main Results:

• Demonstrated independent control over the presence and position of QI features by manipulating bond topology and electronegativity.
• Showed that conductance depends on the position and depth of QI features.
• This is the first study to experimentally separate these two control parameters.

Conclusions:

• Synthetic modification of molecular wires allows for deterministic control over quantum interference (QI) effects.
• This provides a pathway for designing nano-scale electronic devices with tailored conductance properties.