Zero-Bias Anti-Ohmic Behaviour in Diradicaloid Molecular Wires

Area of Science:

• Molecular electronics
• Organic electronics
• Materials science

Background:

• Open-shell materials with multiple spin centers are crucial for efficient charge transport in single-molecule electronics.
• These materials typically exhibit narrow energy gaps, facilitating electron transport.
• Stabilizing open-shell states, especially when in contact with electrodes, is a significant challenge.

Purpose of the Study:

• To design and synthesize stable open-shell compounds for single-molecule electronics.
• To investigate the charge transport properties of novel bis(indeno) fused acenes.
• To overcome the instability issues associated with traditional open-shell materials.

Main Methods:

• Synthesis of a series of bis(indeno) fused acenes.
• Measurement of electrical conductance in single-molecule junctions.
• Density Functional Theory (DFT) calculations to analyze electronic structure and properties.

Main Results:

• The synthesized compounds exhibit stable diradicaloid electronic configurations.
• Observed anti-ohmic behavior with conductance increasing with molecular length.
• Unprecedented rate of conductance increase across the entire bias window.
• DFT calculations confirmed a rapidly narrowing HOMO-LUMO gap responsible for the observed behavior.

Conclusions:

• Bis(indeno) fused acenes offer a stable platform for diradicaloid electronic configurations.
• These materials demonstrate a promising framework for achieving efficient charge transport in neutral compounds.
• The unique electronic structure and stability of these diradicaloid materials hold significant potential for single-molecule electronics.