Structural Stability and Electronic and Optical Properties of Bulk WS 2 from First-Principles Investigations
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https://doi.org/10.1007/s11664-020-08475-2 2020 The Minerals, Metals & Materials Society
Structural Stability and Electronic and Optical Properties of Bulk WS2 from First-Principles Investigations SHUANG CHEN,1 YONG PAN
,1,3 DAJUN WANG,2 and HONG DENG2
1.—Schools of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, China. 2.—State Key Laboratory of Industrial Vent Gas Reuse, Chengdu 610225, China. 3.—e-mail: [email protected]
Tungsten disulfide (WS2) has attracted great attention for use in optoelectronics due to its suitable bandgap and adjustable properties. However, the structure and photoelectric properties of bulk WS2 are not well understood. The first-principles method is applied herein to study the structural stability and electronic and optical properties of WS2. Two phases, viz. hexagonal and rhombohedral, are considered. The results reveal that the two bulk WS2 phases are thermodynamically and dynamically stable based on the enthalpy of formation and phonon dispersion. The structural stability of WS2 is attributed to the S–W–S sandwich structure. The calculated bandgap of hexagonal and rhombohedral WS2 is 1.552 eV and 1.488 eV, respectively, indicating that WS2 is semiconducting. The calculated optical properties show that WS2 exhibits excellent adsorption capacity for ultraviolet light, whether in the hexagonal or rhombohedral structure. Key words: WS2, electronic properties, optical properties, first-principles calculations
INTRODUCTION In the face of the increasing energy crisis and environmental pollution, investigation of high energy density, environmentally friendly, and sustainable energy sources is more significant.1–11 In recent years, transition metal sulfides as the energy storage materials have received extensive attention due to the excellent chemical and physical properties.12–18 Similar to graphene, transition-metal disulfides (TMDs) with interlayer structure are promising energy storage materials.19–22 The general formula of TMDs is MX2, where M represents a transition metal from groups 4–7 and part of groups 8–10, such as Mo, W, Ti, Re,23–25 etc., and X represents a chalcogen (S, Se, Te, etc.), which are connected by strong covalent bonding to form a MX2 layer. The bulk materials are formed along the caxis by MX2 interlayers via weak, van der Waals
(Received May 26, 2020; accepted September 8, 2020)
forces.26,27 The high anisotropy and unique crystal structure of MX228,29 enable potential applications in many fields, such as energy storage and conversion, electrocatalysis, photoelectricity, etc.30,31 Among the TMDs, WS2 is a typical transitionmetal disulfide, being widely used in various energy applications;32,33 For example, Ruppert and Chernikov found using femtosecond broadband pumpprobe spectroscopy that monolayer WS2 exhibits excellent electronic and optical properties.34 Li and Hu applied first-principles calculations to study the structure and electronic properties of p-type-doped WS2 monolayer, while the bandgap of monolayer WS2 is 1.785 e
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