Exploring vibrational properties, Rashba spin splitting, and phonon-limited carrier mobility in Janus WBPX2 (X = S, Se, Te) monolayers.

The search for multifunctional two-dimensional Janus semiconductors has attracted increasing attention due to their potential in next-generation nanoelectronic and spintronic technologies. In this work, we present a comprehensive first-principles investigation of the structural stability, vibrational characteristics, electronic properties, and carrier transport behavior of Janus WBPX2 (X = S, Se, Te) monolayers. The calculated cohesive energies, phonon dispersions, and ab initio molecular dynamics simulations confirm the energetic and thermodynamic stability of all proposed structures. Electronic structure analysis reveals that WBPX2 monolayers are semiconductors with moderate band gaps. When spin-orbit coupling is included, noticeable spin splitting appears in the electronic bands, and the WBPX2 monolayers exhibit a pronounced Rashba effect, indicating strong potential for spintronic applications. Carrier transport analysis further shows that the intrinsic carrier mobility in these systems is relatively low and is primarily limited by acoustic deformation potential scattering. These findings provide deeper insight into the fundamental transport behavior of Janus WBPX2 monolayers and highlight their promising suitability for emerging two-dimensional electronic and spintronic technologies.