Alterations in the Electronic Structure Upon Hierarchical Growth of 2D Networks

Abstract

Surface-supported one-dimensional and two-dimensional polymers fabricated via on-surface synthesis are promising materials for future applications in nanoelectronics. However, the fabrication of extended crystalline 2D polymers in a bottom-up approach directly on a metal surface still presents a challenge in ultra-high vacuum surface science. The irreversible nature of the C–C coupling reaction results in a lack of structural control and in the formation of equilibrium disordered structures featuring a range of different polygons. A multistep, hierarchical synthesis seems promising to improve the network's quality and further allows for measuring the evolution of the electronic properties across different dimensions. The narrowing of the electronic band gap when going from the monomer to 1D and 2D structures gives a direct measure of the effective conjugation in these polymeric materials.