Electronic structure tunability by periodic meta-ligand spacing in one-dimensional organic semiconductors

Abstract

Designing molecular organic semiconductors with distinct frontier orbitals is key for the development of devices with desirable properties. Generating defined organic nanostructures with atomic precision can be accomplished by on-surface synthesis. We use this dry chemistry to introduce topological variations in a conjugated poly-para-phenylene chain in the form of meta-junctions. As evidenced by STM and LEED, we produce a macroscopically ordered, monolayer thin zigzag chain film on a vicinal silver crystal. These cross-conjugated nanostructures are expected to display altered electronic properties, which are now unravelled by highly complementary experimental techniques (ARPES and STS) and theoretical calculations (DFT and EPWE). We find that meta-junctions dominate the weakly dispersive band structure, while the bandgap is tunable by altering the linear segment's length. These periodic topology effects induce significant loss of the electronic coupling between neighboring linear segments leading to partial electron confinement in the form of weakly coupled Quantum Dots. Such periodic quantum interference effects determine the overall semiconducting character and functionality of the chains.

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Cited by in corpus (6)

• Engineering interfacial quantum states and electronic landscapes by molecular nanoarchitectures
• Graphene: Free electron scattering within an inverted honeycomb lattice
• On-surface synthesis and evolution of self-assembled poly($p$-phenylene) chains on Ag(111): a joint experimental and theoretical study
• Steering alkyne homocoupling with on-surface synthesized catalysts
• Controlling the stereospecific bonding motif of Au-thiolate links
• Band structure and energy level alignment of chiral graphene nanoribbons on silver surfaces