Design and Synthesis of Two-Dimensional Covalent Organic Frameworks with Four-Arm Cores: Prediction of Remarkable Ambipolar Charge-Transport Properties

Taylor Allen, Obadiah Reid, Garry Rumbles, Simil Thomas, Hong Li, Raghunath Dasari, Austin Evans, Ioannina Castano, William Dichtel, Nathan Gianneschi, Seth Marder, Veaceslav Coropceanu, Jean-Luc Bredas

Research output: Contribution to journalArticlepeer-review

58 Scopus Citations

Abstract

We have considered three two-dimensional (2D) π-conjugated polymer network (i.e., covalent organic frameworks, COFs) materials based on pyrene, porphyrin, and zinc-porphyrin cores connected via diacetylenic linkers. Their electronic structures, investigated at the density functional theory global-hybrid level, are indicative of valence and conduction bands that have large widths, ranging between 1 and 2 eV. Using a molecular approach to derive the electronic couplings between adjacent core units and the electron-vibration couplings, the three π-conjugated 2D COFs are predicted to have ambipolar charge-transport characteristics with electron and hole mobilities in the range of 65-95 cm2 V-1 s-1. Such predicted values rank these 2D COFs among the highest-mobility organic semiconductors. In addition, we have synthesized the zinc-porphyrin based 2D COF and carried out structural characterization via powder X-ray diffraction, high-resolution transmission electron microscopy, and surface area analysis, which demonstrates the feasibility of these electroactive networks. Steady-state and flash-photolysis time-resolved microwave conductivity measurements on the zinc-porphyrin COF point to appreciable, broadband photoconductivity while transmission spectral measurements are indicative of extended π-conjugation.

Original languageAmerican English
Pages (from-to)1868-1876
Number of pages9
JournalMaterials Horizons
Volume6
Issue number9
DOIs
StatePublished - Nov 2019

Bibliographical note

Publisher Copyright:
© 2019 The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5900-75308

Keywords

  • conjugated polymers
  • couplings
  • density functional theory
  • electronic structure
  • photolysis
  • porphyrins
  • solar-photochemistry

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