Published February 7, 2019 | Version v1
Preprint Open

Graphene Nanoribbons Derived from Zigzag Edge-Encased Poly(para-2,9-dibenzo[bc,kl]coronenylene) Polymer Chains

  • 1. Center for Advancing Electronics Dresden (cfaed) and Faculty of Chemistry and Food Chemistry, Chair for Molecular Functional Materials, Dresden University of Technology
  • 2. Empa, Swiss Federal Laboratories for Material Science and Technology
  • 3. Department of Physics and Astronomy, Shanghai Jiao Tong University
  • 4. Department of Chemistry, University of Zürich
  • 5. Max Planck Institute for Polymer Research
  • 6. Empa, Swiss Federal Laboratories for Material Science and Technology, Department of Chemistry and Biochemistry, University of Bern

Description

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in JACS after peer Review.

Abstract
In this work, we demonstrate the bottom-up on-surface synthesis of poly(para-dibenzo[bc,kl]-coronenylene) (PPDBC), a zigzag edge-encased analog of poly(para-phenylene) (PPP), and its lateral fusion into zigzag edge-extended graphene nanoribbons (zeeGNRs). Toward this end, we designed a dihalogenated di(meta-xylyl)anthracene monomer displaying strategic methyl groups at the substituted phenyl ring and investigated its applicability as precursor in the thermally induced surface-assisted polymerization and cyclodehydrogenation. The structure of the resulting zigzag edge-rich (70%) polymer PPDBC was unambiguously confirmed by scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM). Remarkably, by further thermal treatment at 450 °C two and three aligned PPDBC chains can be laterally fused into expanded zeeGNRs, with a ribbon width of nine (N = 9) up to 17 (N = 17) carbon atoms. Moreover, the resulting zeeGNRs exhibit a high ratio of zigzag (67%) vs armchair (25%) edge segments and feature electronic band gaps as low as 0.9 eV according to gaps quasiparticle calculations.

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