Doped graphene nanoribbons (GNRs) with heteroatoms are a principal strategy to fine-tune the electronic structures of GNRs for future device applications. Here, we successfully synthesized the N = 9 nitrogen-doped armchair GNR on the Au(111) surface. Due to the flexibility of precursor molecules, three different covalent bonds (CÀ C, CÀ N, NÀ N) are formed in the GNR backbone. Scanning tunneling spectroscopy analysis together with band structure calculations reveals that the band gap of the N-9-AGNRs (CÀ C) will be enlarged compared to pristine 9-AGNRs, and the CÀ N bond and NÀ N bond at the isolated site of N-9-AGNR (CÀ C) will introduce new defect states near the Fermi level. DFT calculations reveal that the electronic structure of N-9-AGNR (CÀ C) shows semiconductor character, while N-9-AGNR (CÀ N) and N-9-AGNR (NÀ N) display metallic character. Our results provide a promising route for creating more complex molecular heterostructures with tunable band gaps, which may be useful for future molecular electronics and memory device applications.
Quarteranthene is predicted to manifest nontrivial edge states as the competition from the hybridization of localized frontier states and the Coulomb repulsion between valence electrons, which hosts much research potential in memory, spintronic devices fabrication, and quantum computation. The fabrication of ribbon‐like structures with up‐mentioned edge states, such as chiral graphene nanoribbon, possesses a high significance in the topological phase transition investigation. However, the synthesis of chiral graphene nanoribbon is limited in reactive substrate or with the edge‐brominated precursor. Here, the fabrication of quarteranthene and its chiral graphene nanoribbon segment on Au(111) substrate is reported. A combined bond‐resolved scanning tunneling microscopy, noncontact atomic force microscopy characterization, and corresponding density functional theory calculations confirm the chemical structure of fabricated products on the Au(111) substrate. The detailed analysis of the laterally extended products reveals that the lateral‐extended structures are acquired via the linkage of the hydrocarbon quarter‐anthryl. In addition, several strategies are used to modulate the yield of quarteranthene and its lateral‐extended products. These findings provide a new insight into the lateral extension strategy on metal substrates and provide another possible fabrication strategy of chiral graphene nanoribbons on the relative inert Au(111) substrate.
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