Electronic Band Engineering of Two-Dimensional Kagomé Polymers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Organic Chemistry

Background:

• Two-dimensional conjugated polymers (2DCPs) offer graphene-like properties without a zero bandgap.
• On-surface synthesis enables precise control over 2DCP properties through monomer selection.
• Heteroatom-substituted triangulene 2DCPs are predicted to have graphene-like band structures and high charge mobility.

Purpose of the Study:

• To investigate the electronic properties of a mesoscale-ordered carbonyl-bridged triphenylamine 2DCP (P²TANGO).
• To experimentally demonstrate the presence of a Dirac cone in 2DCPs.
• To measure the energy position of the Dirac cone relative to the vacuum level.

Main Methods:

• On-surface synthesis of P²TANGO.
• Angle-resolved photoemission spectroscopy (ARPES) for electronic property measurement.
• Density functional theory (DFT) calculations for theoretical validation.

Main Results:

• Demonstrated the presence of a Dirac cone in P²TANGO.
• Measured the absolute energy position of the Dirac cone relative to the vacuum level.
• Showed that bridging functionality affects band positioning and ionization energy but not the band structure itself.

Conclusions:

• The electronic properties of 2DCPs are controllable.
• Bridging functionality influences band alignment and ionization energy.
• This work advances the potential of 2DCPs for practical applications.