Strain-enhanced splitting and localization of moiré trions in twisted MoSe ₂ homobilayers

Moiré superlattices in twisted two-dimensional (2D) van der Waals materials offer a versatile platform for engineering quantum states, leading to breakthroughs in correlated insulating phases, superconductivity, and flat-band physics. In particular, the moiré potential in twisted transition metal dichalcogenides (TMDs) can trap excitons and trions, resulting in quantized energy levels and emergent many-body interactions. However, methods for precisely modulating excitonic complexes in these systems remain insufficiently explored. Here, we fabricate 1.3°-twisted R-stacked MoSe₂ homobilayers on prepatterned substrates and investigate strain-engineered moiré trions using spectroscopic techniques at variable temperatures and magnetic fields. In strained twisted MoSe₂, we observe a significant increase in moiré trion emission multiplicity, accompanied by a 65% reduction in linewidth. Raman spectroscopy, second-harmonic generation (SHG) analysis, and density functional theory (DFT) calculations reveal that the enhanced splitting and localization of moiré trion emissions are due to broken symmetry and stronger lattice reconfiguration induced by uniaxial strain, which lifts the degeneracy of flat bands and spatially confines the moiré potential. This work advances the understanding of strain-coupled moiré physics and paves the way for developing quantum light sources and information devices based on moiré superlattices.