Light-matter interaction in tungsten Sulfide-based Janus monolayers: A First-Principles study

We employed a first-principles study based on DFT to predict five new tungsten sulfide-based Janus monolayers: WSC, WSN, WSP, WSAs, and WSO compared with WS2, WSSe, and WSTe monolayers. Our calculations revealed that WSC and WSO monolayers are stable with semiconducting nature, while WSN, WSP, and WSAs demonstrated extreme instability. The WSC Janus was more attractive with a band structure between WS2 monolayer and graphene. Also, the great spin splitting in the VB in all the stable structures was interesting. Moreover, we investigated light-matter interaction, and remarkably we predicted Raman modes, static dielectric constant, static refractive index, and skin depth for stable Janus monolayers. Importantly, our results indicated an anisotropic response of various Janus monolayers with different sensitivity to light. Our calculation showed that not only the Janus structures based on chalcogens could be stable, but also WS-based Janus structures from other groups can be. Due to their novel properties, these new Janus monolayers, especially WSC, can prepare new opportunities for electronic, optoelectronic, and photonic applications.