Structural Control of Band Gap and Polaron Delocalization in 2D Azatriangulene Covalent Organic Frameworks
New two-dimensional (2D) covalent organic frameworks (COFs) with a tri(oxa)azatriangulene (TANG) node and different polarity of the imine linkers (C═N vs N═C) and internode distance have been synthesized using a transimination polymerization. The orientation of the imine linker controls the donor-acceptor interactions in these π-conjugated COFs, resulting in a large modulation of the valence band maximum (-4.2 to -5.4 eV) and the band gap (<i>E</i><sub>g</sub> ≈ 1.2-1.6 eV). <i>p</i>-Doping of COFs in iodine vapor results in the formation of highly delocalized polarons with an absorption band extending into the far-infrared (THz band) region. Reducing the TANG-TANG internodal distance increases the 2D bandwidth dispersion and leads to the highest (in the series) electrical conductivity (10<sup>-1</sup> S/cm), the lowest conductance activation energy (50 meV near room temperature), and the most red-shifted polaron absorption (λ<sub>edge</sub> ∼ 160 μm, 8 meV) in the series.
Authors
- Zhenzhe Zhang (ORCID: https://orcid.org/0000-0002-9983-7729)
- Pegah Ghamari
- Yuze Tao
- Ehsan Hamzehpoor (ORCID: https://orcid.org/0000-0002-5427-9444)
- Dmitrii F. Perepichka (ORCID: https://orcid.org/0000-0003-2233-416X)
- Rustam Z. Khaliullin (ORCID: https://orcid.org/0000-0002-9073-6753)
- Chenghao Liu (ORCID: https://orcid.org/0000-0001-7923-6806)
- Chang Wan Kang (ORCID: https://orcid.org/0000-0001-8153-8248)
- Mohammad Hossein Gohari (ORCID: https://orcid.org/0000-0002-9997-4264)
Institutions
- Institut de Recherche de Chimie Paris (FR)
- McGill University (CA)
- Université de Montréal (CA)
Publication Details
- Journal
- Journal of the American Chemical Society
- Published
- 2025-09-28
- DOI
- https://doi.org/10.1021/jacs.5c10041
- Primary Topic
- Covalent Organic Framework Applications
- Type
- article
- Field-Weighted Citation Impact
- 0.00