Tuning band gaps of transition metal dichalcogenides WX2 (X = S, Se) nanoribbons by external strain

In this paper, we have demonstrated, by first-principle calculations, band gaps of nanoribbons of transition metal dichalcogenides (TMDs) can be modulated by applying strain. We choose MX₂ (M = Mo, W and X = S, Se) nanoribbons for a systematical understanding of strain effect on electronic behavior. Calculation of a series of 1D-MX₂ shows that the band gap of WX₂ has an evident increasing space under a medium strain region, as compared to MoX₂ . WSe₂ nanoribbon is more sensitive to the applied stain among the group of WX₂ . The band gaps increase up to two times higher when the strain changes from -9% to 4%. In addition, two obvious stages can be found for WX₂ in the process of the increase of band gap when subjected to different level strain. Different atom contributions to conduction band (valence band) dominate the increase of band gap at each stage. Our numerical calculation results may provide useful information for the band gap modulation by applied strain in one-dimensional nanostructures based on TMDs.