First-principles study of 3d transition-metal substitution in monolayer WSe2: electronic, magnetic and optical properties

Abstract

Substitutional transition-metal (TM) doping provides an effective route for tailoring the coupled electronic, magnetic, interfacial, and optical properties of monolayer WSe2. In this work, first-principles calculations within a spin-polarized PBE + U framework were systematically performed for W-site substitution by the complete Sc–Zn 3d TM series, with element-specific effective Hubbard parameters determined using a first-principles linear-response approach. The results reveal a clear evolution of the electronic and magnetic states with progressive 3d-orbital filling. Early 3d dopants primarily induce nonmagnetic metallic states, whereas Cr preserves a nonmagnetic semiconducting state. Pronounced local spin polarization emerges for Mn and Fe and persists to varying degrees toward Cu, before disappearing again for Zn. Analysis of the spin-resolved electronic structure, Mulliken populations, and real-space spin density demonstrates that this evolution is governed mainly by spin-dependent occupation of the TM 3d orbitals and their hybridization with neighboring Se 4p states. TM substitution also produces a pronounced nonmonotonic modulation of the work function, with Mn causing the strongest reduction, while the optical response is affected primarily in the low-energy region through dopant-derived states near the Fermi level. Overall, the results establish a systematic relationship among 3d-electron filling, local TM–Se bonding, p-d hybridization, electronic-state reconstruction, local spin polarization, and interfacial/optical response, providing guidance for dopant selection in WSe2-based electronic, optoelectronic, and spin-functional materials.