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 language | American English |
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Pages (from-to) | 1868-1876 |
Number of pages | 9 |
Journal | Materials Horizons |
Volume | 6 |
Issue number | 9 |
DOIs | |
State | Published - 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