The Importance of Dielectric Microenvironments to Electronic Properties of Two-Dimensional Materials: A Theoretical Study Based on Hexabenzocoronene-Cored Graphdiyne

Nonlocal dielectric screening effects have been proven to have a significant impact on the electronic configuration of two-dimensional (2D) materials. Recently, a novel surface synthesis strategy employing thermally induced dehydrogenative coupling has been developed, enabling the successful fabrication of butadiyne-linked hexabenzocoronenes (HBCs) on Au(111) surfaces as core-expanded graphdiyne analogues. However, the experimental determination of its electronic properties is still restricted by the dielectric properties of the substrate materials. In this work, the quasi-particle band gap of the 2D periodic HBC–graphdiyne (HBC–GDY) system is determined to be 2.839 eV at the PBE0 level and 3.424 eV by using the G₀W₀ method, which confirm the influence of metallic substrates on the band gap of its nanosheet in experimental measurements. Similarly, aqueous environments can also reduce its band gap by around 0.4 eV at the PBE0 level due to the dielectric screening effects, suggesting the potential for visible light absorptions. The intrinsic charge carrier mobility reaches an order of magnitude of 10⁴ cm²V^–1s^–1. Additionally, its interactions with Ca and Na atoms as well as the Ca²⁺, Ca⁺, Na⁺, and Cl^– ions are also examined. The adsorption of Ca and Na atoms causes an expected metallization, while the adsorption of the corresponding ions leads to different degrees of band gap reduction. Moreover, the accompanying water molecules of the hydrated ions will partially alleviate this reduction by competitive adsorption. This theoretical study deepens our understanding of the importance of dielectric microenvironments on 2D carbon allotropes and provides insights into the potential applications of HBC–GDY.