Electronic and optical properties of Janus monolayers MoXB2(X=S, Se): first-principles prediction

By means of comprehensive first-principles calculations, we studied the geometric structure, the stability and electronic properties of the new two-dimensional (2D) Janus MoXB 2 (X=S, Se) monolayers. Our calculations demonstrated that the predicted Janus MoXB 2 monolayers are all stable semiconductors with direct band gap. In this paper, we focus on impacts upon the electronic and optical properties of the MoXB 2 monolayers under the different biaxial strains. With the compressive stress increases, the MoXB 2 monolayers would become indirect band gap semiconductors, and then behave as semimetal. While under tensile strain, MoXB 2 still maintain direct band gap. In addition, the optical calculation shows that biaxial strain leads to blue shifts in the optical absorption and reflectivity. The result indicates that MoXB 2 may be promised nano candidate materials in optoelectronic devices.