Interlayer Quasi-Bonding Interactions in 2D Layered Materials: A Classification According to the Occupancy of Involved Energy Bands

Abstract

Recent studies have revealed that the interlayer interaction in two-dimensional (2D) layered materials is not simply of van der Waals character but could coexist with quasi-bonding character. Herein, we classify the interlayer quasi-bonding interactions into two main categories (I: homo-occupancy interaction; II: hetero-occupancy interaction) according to the occupancy of the involved energy bands near the Fermi level. We then investigate the quasi-bonding-interaction-induced band structure evolution of several representative 2D materials based on density functional theory calculations. Further calculations confirm that this classification is applicable to generic 2D layered materials and provide a unified understanding of the total strength of interlayer interaction, which is a synergetic effect of the van der Waals attraction and the quasi-bonding interaction. The latter is stabilizing in main category II and destabilizing in main category I. Thus, the total interlayer interaction strength is relatively stronger in category II and weaker in category I.

p-Type ohmic contact to MoS2via binary compound electrodes

“…These kinds of quasi-bonding character across the vdW gap, named covalent-like quasi-bonding (CLQB), widely exist in layered 2D materials due to the interlayer quasi-bonding interaction. 31,32 Here, we demonstrate the quasi-bonding at the CuS/MoS 2 interface. Due to the weak metallic character of CuS around the Fermi level, the MIGS is suppressed.…”

Few-layer α-Sb2O3 molecular crystals as high-k van der Waals dielectrics: electronic decoupling and significant surface ionic behaviors

“…55 To thoroughly comprehend the layer-dependent band gap, it is essential to consider interlayer QB interactions. As an example, our previous theoretical research 56 on the interlayer QB interaction inferred that typical 2D layered semiconductor materials (like MoS 2 and BP) exhibit out-of-plane orbitals, such as p z orbitals, near the Fermi level for neighboring atoms in the vdW gap. As a result, these out-of-plane orbitals can interact with each other, leading to the energy shifts in the VBM and CBM and thereby enabling the adjustment of the band gap (Fig.…”

Two-dimensional heterostructures formed by graphenelike ZnO and MgO monolayers for optoelectronic applications

“…Alongside vdWHs, recent studies have reported 2D layered heterostructures with interlayer bonding [50,51]. Examples are borophene/graphene [52] and SnP 3 /GeP 3 heterostructures [53].…”

“…Besides, an ab initio study has demonstrated the feasibility of artificial controlling the physical properties of vdWHs by utilizing 2D donor-acceptor heterostructures to create strong bond-like interactions between layers [54]. Interlayer bonding in 2D heterostructures alters the properties of corresponding single layers, which is not so conspicuous in vdWHs [50,55].…”