Modulating Quantum Interference in Coronene-Based Molecular Junctions via Isoelectronic B-N Substitution at Selective...

Area of Science:

• Molecular electronics
• Quantum chemistry
• Materials science

Background:

• Conductance modulation in single-molecule junctions (SMJs) typically requires significant structural or charge state changes.
• Harnessing quantum interference (QI) is key for substantial conductance changes, but often necessitates complex modifications.
• The potential for simple chemical substitution to influence QI and conductance remains an open question.

Purpose of the Study:

• To investigate if isoelectronic boron-nitrogen (B-N) substitution alone can alter quantum interference (QI) behavior.
• To explore the impact of B-N substitution on conductance modulation in coronene-based SMJs.
• To determine if chemical substitution can be a sufficient strategy for controlling QI in molecular junctions.

Main Methods:

• Utilized density functional theory (DFT) combined with non-equilibrium Green's function (NEGF) methods.
• Synthetically explored B-N substitution by selectively replacing carbon-carbon double bonds in coronene.
• Analyzed the effects of B-N substitution at various positions and patterns on molecular orbitals and conductance.

Main Results:

• Position- and pattern-dependent B-N substitutions were found to strongly perturb molecular orbital symmetry, phases, and energies.
• These perturbations effectively switched the quantum interference characteristics within the SMJs.
• Remarkable modulation of conductance was observed due to the altered QI behavior.

Conclusions:

• Isoelectronic B-N substitution can significantly alter QI behavior in coronene-based SMJs.
• This chemical strategy provides a powerful tool for modulating conductance through quantum interference.
• Demonstrates a novel design approach for engineering polyaromatic hydrocarbon-based SMJs with tunable electronic properties.