Theoretical understanding of electronic and mechanical properties of 1T' transition metal dichalcogenide crystals.

Seyedeh Alieh Kazemi,William Wen,Vei Wang,Sadegh Imani Yengejeh,Yun Wang

doi:10.3762/bjnano.13.11

Abstract

Transition metal dichalcogenides (TMDs) with a 1T′ layer structure have recently received intense interest due to their outstanding physical and chemical properties. While the physicochemical behaviors of 1T′ TMD monolayers have been widely investigated, the corresponding properties of layered 1T′ TMD crystals have rarely been studied. As TMD monolayers do not have interlayer interactions, their physicochemical properties will differ from those of layered TMD materials. In this study, the electronic and mechanical characteristics of a range of 1T′ TMDs are systematically examined by means of density functional theory (DFT) calculations. Our results reveal that the properties of 1T′ TMDs are mainly affected by their anions. The disulfides are stiffer and more rigid, diselenides are more brittle. In addition, the 1T′ polytype is softer than 2H TMDs. Comparison with the properties of the monolayers shows that the interlayer van der Waals forces can slightly weaken the TM–X covalent bonding strength, which can further influence the mechanical properties. These insights revealed by our theoretical studies may boost more applications of 1T′ TMD materials.

Highlights

Layered transition metal dichalcogenides (TMDs) have received increasing attention as important and versatile materials for new applications in different sectors from catalysis to energy storage and electronic devices [1,2,3,4,5,6]
Each TMD layer can be described as a sandwich type of structure (X–TM–X), where TM and X are transition metal cations (e.g., Mo and W) and chalcogen anions (e.g., S and Se)
Our results demonstrate that the anisotropic mechanical properties of 1T′ TMD materials are greatly affected by their anions

Summary

Introduction

Layered transition metal dichalcogenides (TMDs) have received increasing attention as important and versatile materials for new applications in different sectors from catalysis to energy storage and electronic devices [1,2,3,4,5,6]. Each TMD layer can be described as a sandwich type of structure (X–TM–X), where TM and X are transition metal cations (e.g., Mo and W) and chalcogen anions (e.g., S and Se). The most extensively studied TMDs, including MoS2, MoSe2, WS2, and WSe2, can display different structural polytypes (e.g., 2H, 3R, 1T, and 1T′) [8]. Previous studies have revealed that the structures significantly affected the properties and physical behavior of the TMD materials and successful applications of the TMDs, depending on proper structural polytypes.

Results

Discussion

Conclusion