| AVS 66th International Symposium & Exhibition | |
| 2D Materials | Wednesday Sessions |
| Session 2D+AS+MI+NS-WeM |
| Session: | 2D Materials Characterization by Scanning Probe Microscopy and Spectroscopy |
| Presenter: | Zachery Enderson, Georgia Institute of Technology |
| Authors: | Z. Enderson, Georgia Institute of Technology H. Murali, Georgia Institute of Technology R. Dasari, Georgia Institute of Technology T.C. Parker, Georgia Institute of Technology S.R. Marder, Georgia Institute of Technology H. Li, Georgia Institute of Technology Q. Dai, Georgia Institute of Technology S. Thomas, Georgia Institute of Technology J.-L. Brédas, Georgia Institute of Technology P.N. First, Georgia Institute of Technology |
| Correspondent: | Click to Email |
Covalent Organic Frameworks (COFs) and similar materials synthesized from bottom-up procedures grant scientists a means to customize a 2D material’s final properties from its initial precursors. The dimethylmethylene-bridged triphenylamine (DTPA) COF is an excellent example of the unique systems one can fabricate with these techniques1. The DTPA COF is initially synthesized on Au(111) or Ag(111) which facilitates crystalline growth through Ullman-type coupling. With an even number of electrons per unit cell, theory predicts a semiconducting electronic structure for the COF. Further heating in vacuum selectively cleaves the dimethyl groups but leaves the framework intact. This final COF resembles an ultra-flat covalent network of triangulene molecules with enticing proposed electronic properties, which depend on how the demethylated sites are terminated. In the case of hydrogen termination at these sites, calculations indicate that the “radical” COF on a metallic substrate will be a half-metal (fully spin-polarized density of states at the fermi energy)2. Using a low-temperature scanning tunneling microscope, the work outlined in this talk presents new information on the electronic structure of the DTPA COF in both its intact (methylated) and radical (demethylated) forms.
[1] Bieri, Marco, Stephan Blankenburg, Milan Kivala, Carlo A. Pignedoli, Pascal Ruffieux, Klaus Müllen, and Roman Fasel. “Surface-Supported 2D Heterotriangulene Polymers.” Chem. Commun. 47, no. 37 (2011): 10239–41. https://doi.org/10.1039/C1CC12490K .
[2] Kan, Erjun, Wei Hu, Chuanyun Xiao, Ruifeng Lu, Kaiming Deng, Jinlong Yang, and Haibin Su. “Half-Metallicity in Organic Single Porous Sheets.” Journal of the American Chemical Society 134, no. 13 (April 4, 2012): 5718–21. https://doi.org/10.1021/ja210822c .