Enhancing spin-photogalvanic effect via defects in armchair-edged monolayer Janus ZrSSe

We investigate the spin-photogalvanic effect (SPGE) in armchair-edged monolayer Janus ZrSSe via the combination of non-equilibrium Green’s function and density functional theory. It is found that defects and doping can optimize the spin photocurrent and spin polarization properties of ZrSSe. The introduction of S vacancies, Se vacancies, Cr doping, and Ni doping induces localized states, breaks symmetry, and engineers the electronic structure. These modifications, in turn, enhance the response of the SPGE and broaden its spectral adaptability. After the introduction of defects and doping, both high-energy domain light absorption and spin polarization are significantly enhanced; among all modified systems, the Cr-doped one exhibits the most remarkable increase in spin photocurrent. This finding highlights that doping and defect engineering can effectively optimize the spin-related properties of ZrSSe, thereby providing a theoretical basis for the design of high-efficiency spin-photonic devices.