  The electronic and structural properties of Janus MoSSe/MoX$_2$ (X=S,Se)
in-plane heterojunctions, endowed with single-atom vacancies, were studied
using density functional theory calculations. The stability of these structures
was verified from cohesion energy calculations. Results showed that single-atom
vacancies induce the appearance of flat midgap states, and a substantial amount
of charge is localized in the vicinity of these defects. As a consequence,
these heterojunctions presented an intrinsic dipole moment. No bond
reconstructions were noted by removing an atom from the lattice, regardless of
its chemical species. Our calculations predicted indirect electronic bandgap
values between 1.6-1.7 eV.
