Available on-demand - *S.NM05.05.04
Bottom-Up Solution Synthesis of Structurally Well-Defined Graphene Nanoribbons—Modulation of the Width and Edge Functionalization
Okinawa Institute of Science and Technology Graduate University1,Max Planck Institute for Polymer Research2
In contrast to zero-bandgap graphene, structurally confined graphene nanoribbons (GNRs) features open bandgaps due to the quantum confinement effect, which render them highly promising for nanoelectronic and optoelectronic applications. The properties of the GNRs are determined by their chemical structures, in particular the width and the edge configuration, which makes their precise structural control essential. Whereas such precision cannot be achieved by “top-down” fabrication methods such as “cutting” of graphene, bottom-up chemical synthesis can afford atomically precise GNRs with various structures.[1,2] The synthesis is carried out through polymerization of a tailor-made monomer leading to a polymer precursor, which can be “planarized” and “graphitized” into GNRs by oxidative cyclodehydrogenation. While it is challenging to obtain very long GNRs through transition-metal-catalyzed or metal-surface-assisted polymerization, we have demonstrated solution synthesis of GNRs with average lengths larger than ~600 nm through AB-type Diels-Alder polymerization.[2,3] Solubilizing alkyl chains can be attached on the GNR edges through the solution synthesis, making them dispersible in organic solvents and thus allowing for the liquid-phase processing for the device integration.[3,4] By modifying the monomer structure, laterally extended GNRs with the width of up to ~2 nm could be obtained, revealing the lowering of the optical bandgap down to ~1.2 eV.[2,5] We have also achieved edge functionalization of the GNRs by introducing a bromo group on the monomer. For example, introduction of perylene monoimide units led modulation of the self-assembly behavior, providing intriguing “rectangular” networks of GNRs. Moreover, introduction of spin-bearing organic radicals on the GNR edges allowed for spin injection to the aromatic core, inducing a delocalized magnetic state, which might have potential for application in the quantum computers. These results form a fundamental basis for applications of such GNRs in the future nanotechnology.
 X.-Y. Wang, A. Narita, K. Müllen, Nat. Rev. Chem. 2017, 2, 0100.
 A. Narita, Z. Chen, Q. Chen, K. Müllen, Chem. Sci. 2019, 10, 964.
 A. Narita, X. Feng, Y. Hernandez, S. A. Jensen, M. Bonn, H. Yang, I. A. Verzhbitskiy, C. Casiraghi, M. R. Hansen, A. H. R. Koch, G. Fytas, O. Ivasenko, B. Li, K. S. Mali, T. Balandina, S. Mahesh, S. De Feyter, K. Müllen, Nature Chem. 2014, 6, 126.
 T. Preis, C. Kick, A. Lex, D. Weiss, J. Eroms, A. Narita, Y. Hu, K. Müllen, K. Watanabe, T. Taniguchi, Appl. Phys. Lett. 2019, 114, 173101.
 Y. Hu, P. Xie, M. De Corato, A. Ruini, S. Zhao, F. Meggendorfer, L. A. Straasø, L. Rondin, P. Simon, J. Li, J. J. Finley, M. R. Hansen, J.-S. Lauret, E. Molinari, X. Feng, J. V. Barth, C.-A. Palma, D. Prezzi, K. Müllen, A. Narita, J. Am. Chem. Soc. 2018, 140, 7803.
 A. Keerthi, B. Radha, D. Rizzo, H. Lu, V. Diez Cabanes, I. C.-Y. Hou, D. Beljonne, J. Cornil, C. Casiraghi, M. Baumgarten, K. Müllen, A. Narita, J. Am. Chem. Soc. 2017, 139, 16454.
 M. Slota, A. Keerthi, W. K. Myers, E. Tretyakov, M. Baumgarten, A. Ardavan, H. Sadeghi, C. J. Lambert, A. Narita, K. Müllen, L. Bogani,, Nature, 2018, 557, 691.