π-Conjugated two-dimensional covalent organic frameworks (2D COFs) are emerging as a novel class of electro-active materials for (opto-)electronic and chemiresistive sensing applications. However, understanding the intricate interplay between chemistry, structure and conductivity in π-conjugated 2D COFs remains elusive. Here, we report a detailed charac-terization for the electronic properties of two novel samples consisting of Zn- and Cu-phthalocyanine-based pyrazine-linked 2D COFs. These 2D COFs are synthesized by condensation of metal-phthalocyanine (M=Zn and Cu) and pyrene derivatives. The obtained polycrystalline-layered COFs are p-type semiconductors both with a band gap of ~1.2 eV. Mobilities up to ~5 cm²/Vs are resolved in the dc limit, which represent a lower threshold induced by charge carrier localization at crystalline grain boundaries. Hall Effect measurements (dc limit) and terahertz (THz) spectroscopy (ac limit) in combination with den-sity functional theory (DFT) calculations demonstrate that varying metal center from Cu to Zn in the phthalocyanine moiety has a negligible effect in the conductivity (~5×10⁻⁷ S/cm), charge carrier density (~10¹² cm⁻³), charge carrier scattering rate (~3×10¹³ s⁻¹), and effective mass (~2.3m₀) of majority carriers (holes). Notably, charge carrier transport is found to be aniso-tropic, with hole mobilities being practically null in-plane and finite out-of-plane for these 2D COFs.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:72450 |
| Date | 04 March 2021 |
| Creators | Wang, Mingchao, Ballabio, Marco, Wang, Mao, Lin, Hung-Hsuan, Biswal, Bishnu P., Han, Xiaocang, Paasch, Silvia, Brunner, Eike, Liu, Pan, Chen, Mingwei, Bonn, Mischa, Heine, Thomas, Zhou, Shengqiang, Cánovas, Enrique, Dong, Renhao, Feng, Xinliang |
| Publisher | American Chemical Society |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 1520-5126, 10.1021/jacs.9b07644, info:eu-repo/grantAgreement/European Commission/H2020 | ERC | ERC-COG/819698//Development of Thiophene Based Conjugated Polymers in Two Dimensions/T2DCP, info:eu-repo/grantAgreement/European Commission/H2020 | ERC | ERC-STG/852909//Development of Functional Conjugated Two-Dimensional Metal-Organic Frameworks/FC2DMOF, info:eu-repo/grantAgreement/Deutsche Forschungsgemeinschaft/Exzellenzcluster/194636624//Center of Advancing Electronics Dresden/cfaed |
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