Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are emerging as a unique class of semiconducting 2D conjugated polymers for (opto)electronics and energy storage. Doping is one of the common, reliable strategies to control the charge carrier transport properties, but the precise mechanism underlying COF doping has remained largely unexplored. Here we demonstrate molecular iodine doping of a metal-phthalocyanine-based pyrazine-linked 2D c-COF. The resultant 2D c-COF ZnPc-pz-I2 maintains its structural integrity and displays enhanced conductivity by 3 orders of magnitude, which is the result of elevated carrier concentrations. Remarkably, Hall effect measurements reveal enhanced carrier mobility reaching μ22 cm2 V-1 s-1 for ZnPc-pz-I2, which represents a record value for 2D c-COFs in both the direct-current and alternating-current limits. This unique transport phenomenon with largely increased mobility upon doping can be traced to increased scattering time for free charge carriers, indicating that scattering mechanisms limiting the mobility are mitigated by doping. Our work provides a guideline on how to assess doping effects in COFs and highlights the potential of 2D c-COFs to display high conductivities and mobilities toward novel (opto)electronic devices.
|Number of pages||6|
|Journal||Journal of the American Chemical Society|
|Publication status||Published - 2020 Dec 30|
Bibliographical noteFunding Information:
We are thankful for financial support from EU Graphene Flagship (GrapheneCore3, 881603), ERC grants (T2DCP, 819698and FC2DMOF, 852909), H2020-MSCA-ITN (ULTIMATE, 813036), DFG projects (COORNETs, SPP 1928 and CRC 1415, 417590517), and the German Science Council, Center for Advancing Electronics Dresden (EXC1056). We acknowledge Dresden Center for Nanoanalysis (DCN) and Dr. Konrad Schneider (IPF, Dresden) for use of their facilities. We thank Dr. Yanpeng Qi, Dr. Xu-Bing Li, Dr. Wei Li, Dr. Yu Zhang, and Jianfeng Zhang for helpful discussions. T.H. and H.-H.L. acknowledge the Centre for Information Services and High Performance Computing (ZIH) in Dresden, Germany, for the provided computational resources. E.C. acknowledges financial support from the Regional Government of Comunidad de Madrid under Projects 2017-T1/AMB-5207 and P2018/NMT-4511 and the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, Grant SEV-2016-0686).
© 2020 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry