Electronic Properties of Bulk and Monolayer TMDs: Theoretical Study Within DFT Framework (GVJ‐2e Method)

Abstract

Accurate prediction of band gap for new emerging materials is highly desirable for the exploration of potential applications. The band gaps of bulk and monolayer TMDs (MoS2, MoSe2, WS2, and WSe2) are calculated with the recently proposed by us GVJ‐2e method, which is implemented within DFT framework without adjustable parameters and is based on the total energies only. The calculated band gaps are in very good agreement with experimental ones for both bulk and monolayer TMDs. For monolayer MoS2, MoSe2, WS2, and WSe2, direct band gaps are predicted to be 1.88 eV, 1.57 eV, 2.03 eV, 1.67 eV correspondingly, and for bulk TMDs, indirect band gaps of 1.23 eV (MoS2), 1.09 eV (MoSe2), 1.32 eV (WS2), 1.21 eV (WSe2) are predicted. The GVJ‐2e method demonstrates good accuracy with mean absolute error (MAE) of about 0.03 eV for TMDs PL gaps (and 0.06 eV for QP gaps). GVJ‐2e method allows to equally accurately obtain band gaps for 3D and 2D materials. The errors of GVJ‐2e method are significantly smaller than errors of other widely used methods such as GW (MAE 0.23 eV), hybrid functional HSE (MAE 0.17 eV), TB‐mBJ functional (MAE 0.14 eV).

Mixed‐Phase 2D‐MoS2 as an Effective Photocatalyst for Selective Aerobic Oxidative Coupling of Amines under Visible‐Light Irradiation

“…[16,17] Bulk MoS 2 ,alayered material, exists naturally in the semiconducting 2H phase, with ab and gap of 1.29 eV whichi ncreases as the materiali s thinned (1.8 eV at monolayer). [18] Experimental and theoretical studies suggest that single-layeredM oS 2 has many polymorphs,a mong them 1T-MoS 2 and2 H-MoS 2 are the most stablep olymorphs. [19] Of significant interest is that both phases can coexist within the same basal plane,t herebyf orming atomically coherentm etal-semiconductor junctions [20] that may prove fruitfulf or enhancedp hotocatalysis.…”

2D Materials for Terahertz Modulation

“…[44,92] This results in a well-defined boundary between their on and off states which is very useful in a device operation (logic circuits, photodetectors, etc.). Interestingly, the structural phases typically stable at room temperature exhibit a semiconducting behavior with bandgaps ranging from visible to near IR energies solely depending on the number of layers.…”

“…Although they do not exhibit high carrier mobility as compared to graphene, unlike graphene, they are semiconducting with nontrivial finite bandgaps. [44,92] This results in a well-defined boundary between their on and off states which is very useful in a device operation (logic circuits, photodetectors, etc.). Optical absorbance (per unit thickness) of TMDCs is comparable to or stronger than conventional semiconductors such as Si, GaAs, and Ge, [93] and resonant absorption phenomena near bandgap causes further enhancement.…”

DFT study of structural and electronic properties of MoS2(1−x)Se2x alloy (x = 0.25)

“…32,33 The final nonlinear equation for the fundamental band gap includes the local density approximation (LDA) band gap and two correction terms when taking into account a nonlocal part of the exchange correlation energy functional and has the form…”

“…31,32 The calculation of the fundamental and optical band gaps of bulk and monolayer TMDs in the GVJ2e method showed more accurate band gaps than the results obtained with the PBE, hybrid functionals [Heyd-ScuseriaErnzerhof (HSE)], and GW. 33 In this paper, we present the theoretical analysis of the energy of formation of a monolayer MoS 2(1-x) Se 2x alloy (x ¼ 0.25) and the microscopic structural stability (different Published by AIP Publishing. 123, 161594-1 alloy configurations with variation in the positions of substituting atoms of Se).…”