Hierarchical on-surface synthesis and electronic structure of carbonyl-functionalized one- and two-dimensional covalent nanoarchitectures.
The fabrication of nanostructures in a bottom-up approach from specific molecular precursors offers the opportunity to create tailored materials for applications in nanoelectronics. However, the formation of defect-free two-dimensional (2D) covalent networks remains a challenge, which makes it difficult to unveil their electronic structure. Here we report on the hierarchical on-surface synthesis of nearly defect-free 2D covalent architectures with carbonyl-functionalized pores on Au(111), which is investigated by low-temperature scanning tunnelling microscopy in combination with density functional theory calculations. The carbonyl-bridged triphenylamine precursors form six-membered macrocycles and one-dimensional (1D) chains as intermediates in an Ullmann-type coupling reaction that are subsequently interlinked to 2D networks. The electronic band gap is narrowed when going from the monomer to 1D and 2D surface-confined π-conjugated organic polymers comprising the same building block. The significant drop of the electronic gap from the monomer to the polymer confirms an efficient conjugation along the triphenylamine units within the nanostructures.
Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erwin-Rommel-Strasse 1, 91058 Erlangen, Germany.
Christian
C
Steiner
Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
Julian
J
Gebhardt
Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erwin-Rommel-Strasse 1, 91058 Erlangen, Germany.
Maximilian
M
Ammon
Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erwin-Rommel-Strasse 1, 91058 Erlangen, Germany.
Zechao
Z
Yang
Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
Alexander
A
Heidenreich
Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
Natalie
N
Hammer
Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
Andreas
A
Görling
Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
Milan
M
Kivala
Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erwin-Rommel-Strasse 1, 91058 Erlangen, Germany.
Sabine
0000-0001-9589-6855
S
Maier