Electronic and optical properties of WS2(6,6)@MoS2(14,14) and WS2(8,8)@MoS2 (16,16) van der Waals nanotubes under the influence of an external electric field

One-dimensional nanostructures based on transition metal dichalcogenides (TMDs) have attracted considerable attention for applications in next-generation quantum devices. However, the influence of external factors on their electronic and optical properties remains insufficiently understood. In this study, the effects of an external electric field on the electronic and optical properties of 1D van der Waals (vdW) heterostructures WS2(6,6)@MoS2(14,14) and WS2(8,8)@MoS2(16,16) were investigated within the framework of density functional theory (DFT) using the GGA-PBE approximation. The electronic band structures, complex dielectric functions, absorption coefficients, and refractive indices were computed. The results show that with increasing external electric field strength: the band gap of the vdW heterostructures WS2(6,6)@MoS2(14,14) and WS2(8,8)@MoS2(16,16) decreases, and a semiconductor-to-metal transition occurs at field strengths of 16 V and 18 V, respectively; the values of static dielectric permittivity increase due to charge redistribution; the amplitude of the absorption coefficient peak decreases and shifts to the low-energy region as a result of charge redistribution and enhanced ionic polarizability.