Polarization-Dominated Exciton Behavior of the MoSSe/GaN Heterostructure under Strain: A First-Principles Study

Excitons have a profound effect on the electronic and optical properties of low-dimensional materials. Here, we systematically investigate the effect of strain on the excitonic behavior of MoSSe/GaN heterostructures using first-principles calculations based on the G 0 W 0 approximation and the Bethe–Salpeter equation (BSE). We identify two stable AB-stacked configurations, SeMoS/GaN and SMoSe/GaN, whose inherent polarization leads to the formation of interlayer excitons with binding energies of approximately 0.5 and 0.47 eV, respectively. A key finding is that, unlike in traditional cases, strain can be engineered to either increase or decrease the exciton binding energy within this single material system, a behavior controlled exclusively by the polarization direction. Furthermore, the spatial distribution of the exciton is highly tunable; the interlayer exciton is robustly maintained in the SeMoS/GaN structure regardless of strain, while in the reverse-polarized SMoSe/GaN configuration, it transitions to an intralayer exciton as compressive strain reaches −6%. This unique behavior is strongly related to the strain-dependent dielectric environment and dipole moment of the heterostructure. Our findings pave the way for manipulating excitonic properties by utilizing the polarization and strain degrees of freedom in polarized low-dimensional materials.