Strain-Driven Modulation of Moiré Exciton Dynamics and Valley Polarization in Twisted WSe₂ Homobilayers

Moiré superlattices have emerged as a powerful platform for engineering quantum materials, where lattice mismatch modifies electronic structures to produce flat minibands and novel correlated states, including insulating phases and topological excitons. However, achieving spatially precise control over the moiré potential and symmetry remains elusive. This study demonstrates a strain modulation strategy based on patterned gold grating substrates, enabling spatially controlled exciton localization in 3.6° twisted WSe₂ homobilayers. Under this engineered strain, the moiré exciton emission peak exhibits enhanced splitting, a remarkable 43% reduction in spectral linewidth, and substantially enhanced luminescence intensity. Temperature-dependent photoluminescence (PL) measurements reveal that strain-deepened moiré potential effectively suppresses exciton dissociation. Furthermore, circularly polarized PL under applied magnetic fields shows strain-enhanced Zeeman splitting and a threefold increase in the slope of valley polarization versus magnetic field. First-principles calculations confirm that the strain-mediated band structure modification and charge redistribution collectively enhance the localization effects. These findings establish a robust approach for precisely manipulating moiré excitons and pave a pathway for exploring strongly correlated quantum states.