Photodoping-Driven Lattice Expansion Enables Polarization Enhancement in Sliding Ferroelectric MoS2

Abstract Light-matter interactions provide a powerful route to dynamically control ferroelectricity in low-dimensional materials, yet the microscopic mechanisms governing light-induced polarization remain elusive in sliding ferroelectrics. However, the influence of photodoped carriers on the macroscopic polarization and lattice responses remains largely unexplored. In this work, we employ first-principles calculations to demonstrate the microscopic origin of the photostrictive response in rhombohedral bilayer MoS2 under carrier photodoping. The system exhibits a characteristic lattice deformation, including in-plane expansion with the magnitude of 2% under a moderate photodoping density, collectively enhancing electronic hybridization. The coupling gives rise to a substantial interlayer contraction and an increase in out-of-plane spontaneous polarization, accompanied by a softening of the interlayer vibrational mode. These results demonstrate a microscopic, nonthermal pathway for modulating ferroelectric properties and underscore the potential of lattice-engineered polarization control in two-dimensional sliding ferroelectrics for advanced optoelectronic and information storage technologies.