External electric field modulation of single-layer MoSe2 electronic and optical properties: A first-principles investigation

A wisely applied external electric field could effectively develop the optoelectronic properties of single-layer materials. The optical and electronic characteristics of monolayer molybdenum diselenide (ML-MoSe2) are deeply studied by means of density functional computations (DFT) to pinpoint the effect of the out-of-plane applied electric field (F//Oz). In fact, variations in the applied electric field strength gradually increase the energy of the electronic band gap (Eg) from 1.44 eV at 0V/& ANGS; to 1.51 eV at & PLUSMN;0.6V/& ANGS;. We also probed a sharp drop in the energy gap at high intensities. However, dielectric function, reflectivity, and loss function are studied for unpolarized and polarized incident light. Interestingly, the 001-polarization of the incident light affects the dielectric function's magnitude and position; this effect is more emphasized in the presence of an electric field with positive strengths. Furthermore, we found that the applied negative/positive electric field enhances the UV-visible reflectivity. Also, blue shifts of the ML-MoSe2 optical properties spectrum appear when subjected to the 001-polarized incident light. However, the loss function exhibits a weak response to the applied F. Additionally, we obtain that the 001-light polarization improves a plasmonic peak around 100 nm. Our results will provide a new view to understanding the controllable optical and electronic properties of MoSe2 monolayer, which is valuable for the design of new optoelectronic and plasmonic devices under development.