The transport and optical sensing properties of MoS_2, MoSe_2, WS_2 and WSe_2 semiconducting transition metal dichalcogenides

摘要

In this paper, we investigate the transport and optical properties of the monolayer semiconducting transition metal dichalcogenides (STMDs) in the absence and presence of the NH3, NO, NO2, and O-2 gas molecules to assess their potentials as gas sensors. The first-principles calculations based on density functional theory indicate that absorption of the O-2, NO2, NO gas molecules on the surface of these materials leads to significant changes in their transmission spectrum. Our calculations predict a charge transfer between the adsorbent gas and any of these STMDs. However, the presence of NH3 molecule has little effect on the transport properties of these materials. The results show that when the STMDs are exposed to NO, NO2, and O-2 molecules, the dielectric function changes. Therefore, these materials can be employed as the sensing element in an optical gas sensor.