First-Principles Analysis of Photoelectric and Magnetic Tunability in Transition Metal-Doped Janus MSeX Monolayers (M = Mo, W; X = S, Te)

In this study, the modulation effect of transition metal (TM) doping on the electronic, magnetic, and optical properties of the Janus MSeX monolayers (M = Mo, W; X = S, Te) system is systematically investigated by applying the GGA + U methodology in the context of density functional theory. Phonon spectral and thermodynamic analyses confirm the dynamic stability of these systems and the differences in their thermophysical properties. The stability of the doped systems is evaluated in terms of formation and binding energies. Specific TM doping, such as V, Mn, and Fe, induces magnetic semi-metallic behavior in the MSeX system. Ta, Tc, and Re doping exhibit different magnetic and electronic properties in different systems. In addition, the doping-induced redshift of the light absorption edge and the appearance of new absorption peaks significantly enhance the material’s responsiveness to the infrared to the visible range. This study deepens the understanding of the physical properties of Janus materials and provides a theoretical basis for their potential in thermoelectric, sensing, and optoelectronic material applications.