Two-dimensional materials with high charge carrier mobility and tunable band gaps have attracted intense research effort for their potential use in nanoelectronics. Two-dimensional π-conjugated polymers constitute a promising subclass because the band structure can be manipulated by varying the molecular building blocks while preserving key features such as Dirac cones and high charge mobility. The major barriers to the application of two-dimensional π-conjugated polymers have been the small domain size and high defect density attained in the syntheses explored so far. Here, we demonstrate the fabrication of mesoscale ordered two-dimensional π-conjugated polymer kagome lattices with semiconducting properties, Dirac cone structures and flat bands on Au(111). This material has been obtained by combining a rigid azatriangulene precursor and a hot dosing approach, which favours molecular diffusion and eliminates voids in the network. These results open opportunities for the synthesis of two-dimensional π-conjugated polymer Dirac cone materials and their integration into devices.
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The authors declare that the main data supporting the findings of this study are available within the article and its Supplementary information, while DFT calculations can be found at the following web repositor: https://doi.org/10.17172/NOMAD/2020.04.05-1. Extra data are available from the authors upon request.
The codes and algorithms used for the statistical analysis of the STM images are available from the following web repository: https://github.com/lvbesteiro/STM-Minimum_Spanning_Tree.
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This work was partially supported by the project Grande Rilevanza Italy-Quebec of the Italian Ministero degli Affari Esteri e della Cooperazione Internazionale (MAECI), Direzione Generale per la Promozione del Sistema Paese. M.C.G., D.F.P. and F.R. acknowledge funding from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Fonds Québécois de la Recherche sur la Nature et les Technologies (FQNRT) through a Team Grant. The work at McGill was supported by the US Army Research Office (grant W911NF-17-1-0126). F.R. is grateful to the Canada Research Program for funding and partial salary support. The authors acknowledge beamtime access and support from the Elettra light source in Italy. We thank N. Preetha Genesh for help with ambient STM imaging. G.G., F.F. and G.C. thank N. Zema for laboratory support and useful discussions. Computations were performed mostly on the Niagara supercomputer at the SciNet HPC Consortium, funded by the Canada Foundation for Innovation under Compute Canada, the Government of Ontario, Ontario Research Fund – Research Excellence and the University of Toronto, and in part on the Graham and Cedar clusters of Compute Canada. The simulations were also enabled by the facilities of the Shared Hierarchical Academic Research Computing Network as well as WestGrid. A.K.K., P.M.S. and P.M. acknowledge the project EUROFEL-ROADMAP ESFRI.
The authors declare no competing interests.
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Galeotti, G., De Marchi, F., Hamzehpoor, E. et al. Synthesis of mesoscale ordered two-dimensional π-conjugated polymers with semiconducting properties. Nat. Mater. (2020). https://doi.org/10.1038/s41563-020-0682-z
Nature Materials (2020)