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Updated: Jan 16, 2026

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
Published on: October 12, 2019
Structural Control of Band Gap and Polaron Delocalization in 2D Azatriangulene Covalent Organic Frameworks
Chang Wan Kang1, Ehsan Hamzehpoor1,2, Pegah Ghamari1
1Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada.
None:
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 (Eg ≈ 1.2-1.6 eV). p-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 (10-1 S/cm), the lowest conductance activation energy (50 meV near room temperature), and the most red-shifted polaron absorption (λedge ∼ 160 μm, 8 meV) in the series.
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