Controlled edge dependent stacking of WS2-WS2 Homo- and WS2-WSe2 Hetero-structures: A Computational Study

TL;DR

This computational study investigates the electronic structure and stability of WS2-WS2 homo- and WS2-WSe2 heterostructures, revealing edge termination preferences and implications for bilayer formation.

Contribution

It provides detailed insights into edge-dependent stacking and stability of TMD bilayers using density functional theory, highlighting the preference for chalcogenide termination.

Findings

Chalcogenide-terminated structures are more stable than metal-terminated ones.

Metal-terminated TMD bilayers are unlikely to form naturally.

Edge termination influences the stability and stacking of TMD bilayers.

Abstract

Transition Metal Dichalcogenides (TMDs) are one of the most studied two-dimensional materials in the last 5-10 years due to their extremely interesting layer dependent properties. Despite the presence of vast research work on TMDs, the complex relationship between the electrochemical and physical properties make them the subject of further research. Our main objective is to provide a better insight into the electronic structure of TMDs. This will help us better understand the stability of the bilayer post-growth homo/hetero products based on the various edge-termination, and different stacking of the two layers. In this regard, two Tungsten (W) based non-periodic chalcogenide flakes (sulfides and selenides) were considered. An in-depth analysis of their different edge termination and stacking arrangement was performed via Density Functional Theory method using VASP software. Our finding indicates the preference of chalcogenide (c-) terminated structures over the metal (m-) terminated structures for both homo and hetero layers, and thus strongly suggests the nonexistence of the m-terminated TMDs bilayer products.