Equibiaxial strain: tunable electronic structure and optical properties of bulk and monolayer MoSe2

Using ab initio calculations based on density functional theory, we have studied the equibiaxial strain effect on the electronic and optical properties of bulk and monolayer MoSe 2 . Very low value of the elastic constants of monolayer MoSe 2 compared to bulk MoSe 2 suggests that the tailoring of the electronic structure and optical properties of monolayer MoSe 2 may easily be achieved by strain. We find that the band gap ( E g ) of MoSe 2 undergoes a transition from indirect to direct upon reducing the thickness of the monolayer which is associated with an enhancement of E g and is further tunable by strain engineering. We noticed that the splitting of the bands that generally determines the luminescence property of MoSe 2 can be modified by strain. Strain effect on bond ionicity, dielectric property (real and imaginary component) of bulk and monolayer MoSe 2 has also been briefly discussed. We noticed that the plasma oscillation, found in bulk MoSe 2 , is absent in MoSe 2 monolayer.