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A first-principles method was used to explore the influence of tensile strain on the electrical and optical characteristics of Nb-doped MoSe2. The tensile strain has been discovered to have a higher influence on the electrical structure of the Nb-doped MoSe2 system than pure monolayer MoSe2. According to the energy band structure study, the pure monolayer MoSe2 is a direct bandgap semiconductor, but the system doped with Nb instead of Mo atoms is a p-type-doped semiconductor. The bandgap of the Nb-doped MoSe2 system decreases gradually with the increase of tensile strain, but still maintains the p-type semiconductor properties, and the bandgap of the pure monolayer MoSe2 also decreases gradually with the increase of tensile strain. From the density of states analysis, it is found that for the total density of states of the doped system at different tensile strains, it is mainly contributed by the Mo-4d and Se-4p orbitals. The optical properties analysis showed that the doped system under tensile strain had higher absorption coefficient and reflectance peak than the Nb-doped MoSe2 system without tensile strain. Additionally, the doped system showed redshift phenomenon in both the absorption and reflection peaks as the tensile strain increased. [ABSTRACT FROM AUTHOR]

The lack of a bandgap in stanene severely limits its outstanding characteristics in optoelectronic devices. Using first-principles calculations, we systematically investigate the effects of full hydrogenation and shear deformation on the electronic structure and optical properties of stanene. Hydrogenation exerts a remarkable impact on electronic structure of stanene, enabling surface state transition from quasi-metallic to semiconducting. Shear degrades the structural stability of full-hydrogenated stanene (FHstanene). FHstanene exhibits a tunable bandgap of 1.327 eV, which can be further reduced to 0.719 eV through shear deformation. The presence of spin-orbit coupling (SOC) induces band splitting in FHstanene. The maximum optical absorption of FHstanene occurs at 291 nm, while the reflectance peak is observed at 449 nm. The variation in bandgap due to deformation results in a redshift in the absorption coefficient and reflectance, and shear deformation increases the reflectance of FHstanene. These findings broaden the application prospects of stanene in novel nano-optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this paper, the structural, electrical and optical effects of WS2 doped with silicon atoms after torsional deformation are investigated using first-principles calculations. First-principles calculations for metal disulfide-WS2. The doping of Si atoms gives WS2 a tunable band gap, and the surface state is successfully transformed from a 2.0 eV band gap to a quasi-metal with a 0.254 eV band gap, and the change of the doped Si atoms causes a redshift in the absorption peak and a blueshift in the reflection peak. The band gap of WS2 can be effectively adjusted by torsional deformation on the basis of Si-doped atoms in the range 0.254–0.052 eV. Calculations of optical properties show that Si-doped WS2 with a torsion angle of 1 0 ∘ has the lowest light absorption peak and Si-doped WS2 with a torsion angle of 8 ∘ has the lowest light reflection peak. This paper opens up new possibilities for designing materials on demand. [ABSTRACT FROM AUTHOR]

Two-dimensional stanene is limited in its application in nanoscale optoelectronic devices due to its zero-bandgap. Based on first-principles calculations of density functional theory, the effects of adsorption of Be atoms with different coverages and torsional deformation on the structure, electricity, and optics of stanene are systematically investigated. The adsorption of Be atoms makes stanene have an adjustable bandgap, the surface state is successfully transformed from a zero-bandgap quasi-metal to a semiconductor with a maximum bandgap of 0.260 eV, the change in Be atom coverage causes a blueshift of the absorption and reflection peaks. Torsional deformation can effectively adjust the bandgap of stanene, which varies from 0.278 eV to 0.110 eV. Torsion enhances the maximum absorption peak of light. Stanene is expected to be a candidate material for designing new nanoelectronic devices. [ABSTRACT FROM AUTHOR]

In this paper, the structural, electrical and optical effects of WS2 doped with silicon atoms after torsional deformation are investigated using first-principles calculations. First-principles calculations for metal disulfide-WS2. The doping of Si atoms gives WS2 a tunable band gap, and the surface state is successfully transformed from a 2.0 eV band gap to a quasi-metal with a 0.254 eV band gap, and the change of the doped Si atoms causes a redshift in the absorption peak and a blueshift in the reflection peak. The band gap of WS2 can be effectively adjusted by torsional deformation on the basis of Si-doped atoms in the range 0.254–0.052 eV. Calculations of optical properties show that Si-doped WS2 with a torsion angle of 1 0 ∘ has the lowest light absorption peak and Si-doped WS2 with a torsion angle of 8 ∘ has the lowest light reflection peak. This paper opens up new possibilities for designing materials on demand. [ABSTRACT FROM AUTHOR]