Revealing the Local Electronic Structure of a Single-Layer Covalent Organic Framework through Electronic Decoupling

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  • Daniel J. Rizzo, UC Berkeley
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  • Qingqing Dai, King Abdullah University of Science and Technology, Georgia Institute of Technology
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  • Christopher Bronner, UC Berkeley
  • ,
  • Gregory Veber, UC Berkeley
  • ,
  • Brian J. Smith, Bucknell University
  • ,
  • Michio Matsumoto, Northwestern University, National Institute for Materials Science Tsukuba
  • ,
  • Simil Thomas, King Abdullah University of Science and Technology, Georgia Institute of Technology
  • ,
  • Giang D. Nguyen, UC Berkeley
  • ,
  • Patrick R. Forrester, UC Berkeley
  • ,
  • William Zhao, UC Berkeley
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  • Jakob H. Jørgensen
  • ,
  • William R. Dichtel, Northwestern University
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  • Felix R. Fischer, UC Berkeley, Lawrence Berkeley National Laboratory
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  • Hong Li, King Abdullah University of Science and Technology, Georgia Institute of Technology
  • ,
  • Jean Luc Bredas, King Abdullah University of Science and Technology, Georgia Institute of Technology
  • ,
  • Michael F. Crommie, UC Berkeley, Lawrence Berkeley National Laboratory

Covalent organic frameworks (COFs) are molecule-based 2D and 3D materials that possess a wide range of mechanical and electronic properties. We have performed a joint experimental and theoretical study of the electronic structure of boroxine-linked COFs grown under ultrahigh vacuum conditions and characterized using scanning tunneling spectroscopy on Au(111) and hBN/Cu(111) substrates. Our results show that a single hBN layer electronically decouples the COF from the metallic substrate, thus suppressing substrate-induced broadening and revealing new features in the COF electronic local density of states (LDOS). The resulting sharpening of LDOS features allows us to experimentally determine the COF band gap, bandwidths, and the electronic hopping amplitude between adjacent COF bridge sites. These experimental parameters are consistent with the results of first-principles theoretical predictions.

Original languageEnglish
JournalNano Letters
Volume20
Issue2
Pages (from-to)963-970
Number of pages8
ISSN1530-6984
DOIs
Publication statusPublished - Feb 2020

    Research areas

  • 2D polymer, biphenyl COF (BP-COF), Covalent organic frameworks (COFs), density functional theory (DFT), Kagome lattice, scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS)

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