Electronic and optical properties of monolayer magnesium diboride under biaxial strain

Monolayer magnesium diboride (MgB${}_2$), a novel 2D material, has garnered significant interest due to its unique physical properties. This paper studies theoretically the electronic band structures, phonon dispersions and optical properties of the MgB${}_2$ monolayer under in-plane biaxial strain using first-principles calculations. The results show that the electronic states and dielectric functions are significantly modulated by strain, suggesting it is an effective way to achieve the target electronic and optical properties. At the same time, based on the phonon analysis, we proved that the system remains dynamically stable in the range of $-2\text{\%}$ to 5% biaxial strain. Moreover, our results show that the MgB${}_2$ monolayer exhibits high transmissivity in the visible region due to its low absorption and reflectivity, making it an excellent candidate for optoelectronic applications such as transparent electrodes. On the other hand, the high absorption and reflectivity in the UV region indicate that it absorbs light most effectively in the ultraviolet spectrum. This characteristic demonstrates its suitability for applications requiring UV absorption, detection, and protection, such as UV filters and photodetectors.