On-Surface Synthesis and Characterization of Cumulene-Linked Stone-Wales Polymers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Organic Chemistry

Background:

• Graphene nanostructures offer tunable electronic properties through modifications like nonbenzenoid ring topologies.
• Stone-Wales (SW) defects, while offering unique characteristics, are challenging to incorporate systematically into graphene.
• Developing methods for controlled defect integration is crucial for advancing carbon-based materials.

Purpose of the Study:

• To demonstrate the on-surface synthesis of one-dimensional polymers incorporating SW defects.
• To investigate the structural and electronic properties of these novel SW-based polymers.
• To explore the potential of SW defects in designing advanced carbon-based conjugated materials.

Main Methods:

• On-surface synthesis using a tailored molecular precursor on Au(111) under thermal and visible-light conditions.
• Characterization via scanning tunneling microscopy (STM), noncontact atomic force microscopy (NC-AFM), and Raman spectroscopy.
• Theoretical modeling and scanning tunneling spectroscopy (STS) for structural and electronic analysis.

Main Results:

• Successful synthesis of one-dimensional SW-based polymers linked by cumulene bonds.
• Experimental verification of nonplanar SW units within the polymer chain and confirmation of chemical structure.
• Measurement of a significant experimental bandgap of 1.8 eV, distinct from related structures.

Conclusions:

• SW defects play a critical role in determining the structural and electronic properties of conjugated polymers.
• The on-surface synthesis approach provides a viable route for incorporating SW defects into polymer chains.
• These findings advance the design of carbon-based materials for next-generation optoelectronic applications.