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Engineering molecular bandgap by bottom-up synthesis of varied-width graphene nanoribbons

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a) Synthesis of GNR heterojunctions from molecular building blocks 1 and 2. b) High-res STM (scanning tunneling microscope) image of GNR heterojunction, with larger-scale image of multiple junctions inset.

Scientific Achievement
Connected pre-designed molecular building blocks to create shape-tunable graphene nanoribbons (GNRs), whose width and bandgap varies with atomic-scale precision along the length of a single GNR.

Significance and Impact
The ability to control and vary GNR width and the resulting bandgap enables creation and exploration of new molecular-scale heterojunctions with atomic precision.

Research Details

  • Synthesized individual molecules of different widths with specific functional groups that allow them to assemble via covalent bonding into width-varying graphene nanoribbons
  • Used scanning tunneling and atomic force microscopy to characterize the resulting molecular structure and electronic properties, and compared experimental data to theoretical predictions
  • Discovered new interface state; unprecedented control over nanoribbon shapes and properties

Y Chen, T Cao, C Chen, Z Pedramrazi, D Haberer, D de Oteyza, F Fischer, S Louie, and M Crommie, Nature Nanotech. 2014, doi:10.1038/NNANO.2014.307