Tunable Symmetry-Breaking-Induced Dual Functions in Stable and Photoswitched Single-Molecule Junctions

Area of Science:

• Molecular electronics
• Nanotechnology
• Materials Science

Background:

• Miniaturizing electronic devices to the single-molecule level is a significant challenge in molecular electronics.
• Developing molecules with diverse structures for specific electronic functions is crucial for nanocircuit construction.

Purpose of the Study:

• To achieve simultaneous gate-controlled rectification and high-performance field effect in a single-molecule device.
• To explore the mechanism of symmetry breaking in molecular orbitals for electronic control.

Main Methods:

• Fabrication of a single-molecule photoswitch using a dinuclear ruthenium-diarylethene (Ru-DAE) complex covalently bonded between graphene electrodes.
• Utilizing experimental and theoretical approaches to analyze molecular orbital behavior under gate electric fields.
• Employing light stimulus to switch the diarylethene unit between open-ring and closed-ring forms.

Main Results:

• Demonstrated a gate-controlled rectifying function with an on/off ratio of approximately 60.
• Achieved a high-performance field effect with a maximum on/off ratio exceeding 100.
• Observed asymmetric orbital shifting (AOS) under gate fields, lifting orbital degeneracy and breaking molecular symmetry.

Conclusions:

• Gate-controlled symmetry breaking in Ru-DAE molecules enables tunable diode-like behavior and enhanced field-effect performance.
• The light-switchable nature of the diarylethene unit allows for on/off control of the molecular symmetry-breaking effect.
• This strategy provides a general approach for creating multifunctional molecular nanocircuits.