Unraveling the Band Structure and Orbital Character of a π‐Conjugated 2D Graphdiyne‐Based Organometallic Network

TL;DR

This paper studies a new 2D carbon-based material with unique electronic properties, revealing its band structure and orbital characteristics.

Contribution

The work presents a novel 2D organometallic network with defined orbital character and electronic conjugation, synthesized on Ag(111).

Findings

The network forms two intense electronic band-manifolds with strong π-conjugation.

Orbital character is linked to specific regions of sp–sp² monomers via DFT calculations.

Halogen by-products cause energy shifts in pore-confined states.

Abstract

Graphdiyne‐based carbon systems generate intriguing layered sp–sp
2 organometallic lattices, characterized by flexible acetylenic groups connecting planar carbon units through metal centers. At their thinnest limit, they can result in 2D organometallic networks exhibiting unique quantum properties and even confining the surface states of the substrate, which is of great importance for fundamental studies. In this work, the on‐surface synthesis of a highly crystalline 2D organometallic network grown on Ag(111) is presented. The electronic structure of this mixed honeycomb‐kagome arrangement – investigated by angle‐resolved photoemission spectroscopy and scanning tunneling spectroscopy – reveals a strong electronic conjugation within the network, leading to the formation of two intense electronic band‐manifolds. In comparison to theoretical density functional theory calculations, it is observed that these bands exhibit a well‐defined orbital character that can be associated with distinct regions of the sp–sp
2 monomers. Moreover, it is found that the halogen by‐products resulting from the network formation locally affect the pore‐confined states, causing a significant energy shift. This work contributes to the understanding of the growth and electronic structure of graphdiyne‐like 2D networks, providing insights into the development of novel carbon materials beyond graphene with tailored properties.

An extended graphdiyne‐based, sp–sp
2 organometallic framework is evaporated on the Ag(111) surface, starting from a brominated molecular precursor. Scanning tunneling spectroscopy, angle‐resolved photoemission spectroscopy, and theoretical calculations are performed to determine the electronic band structure and π‐conjugation, as well as to assign the orbital character and the orbital distribution in real space.

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