Electronic Properties and Charge Transfer of Topologically Protected States in Hybrid Bismuthene Layers

Abstract

We have performed first-principles calculations of electronic and dielectric properties of singlelayer bismuth (bismuthene) adsorbed with -COOH. We show that the Bi-COOH hybrid structure is a two-dimensional topological insulator with protected edge Dirac states. The adsorption process of -COOH induces a planar configuration to the initially pristine buckled bismuthene. We claim that the stability of these planar structure mainly stem from strain induced by the adsorption of the -COOH organic group, but it is also related to ligand-ligand interactions. Using charge density analysis we show that the role of this organic group is not only to stabilize the layer but also to functionalize it, which is very important for future applications such as sensing, biomolecules immobilization, as well in electronic spintronic and even optical devices, due to its large band gap.Finally we demonstrate that many body corrections are crucial to obtain a better description of the electronic and dielectric properties of these systems.

New Pentaoctite Phase of Group‐V Nanostructures

“…[44] In group-V materials, hexagonal and pentaoctite bismuth monolayers have been predicted to be a 2D topological insulator (TI). [13,14,[45][46][47][48][49] To investigate whether the pentaoctite structures behave like topological insulators, we have calculated the Z 2 invariant according to the study by Kane. [43] On the contrary of pentaoctite Bi, our investigated hexagonal and pentaoctite structures are not topological insulators.…”

“…Because of optical selection rules, anisotropy in the optical spectra is seen. Anisotropy has also been reported in layered monochalcogenide of germanium sulfide (GeS), [ 50 ] black phosphorous, [ 51 ] bismuthene, [ 42,49 ] and germanene. [ 52 ] The systems with a gap show finite absorption limits for both parallel and perpendicular directions with larger intensity for the component.…”

Chemical Functionalization of Ultrathin Tin Layers

“…Several ligands have been used to investigate functionalization of 2D materials. In this work, we follow a similar approach to our previous calculations reported in the study by da Rosa et al [36] and Hanh et al [37] Calculations for the following ligands ÀH, ÀOH, ÀCH 3 , ÀC 2 H, ÀI, and ÀF have been performed. We have analyzed their relaxation, charge density distribution, band structure, and dielectric function.…”

“…[38][39][40][41] This is rather different from what has been found for similar organic ligands on group-V nanostructures which become planar upon adsorption. [36,42] As a consequence, both the intralayer lattice parameter a and SnÀSn distance are slightly dependent on the ligand type. The SnÀX (X ¼ H,C) distance d x varies from 1.74 Å (for H adsorption) to 2.73 Å for ÀF adsorption.…”

“…Anisotropy in the optical spectra is seen, similar to other 2D materials. [36,37,49] The systems with a gap show finite absorption limits for both parallel and perpendicular directions with larger intensity for the ε k component. As discussed in the study by Jiang et al, [6] both ligand size and electronegativity can change the bond length and bandgap of functionalized layers.…”