Engineering moiré potentials in twisted bilayer MoS₂ for selective single-molecule sensing

Twisted bilayer MoS₂ forms a quantum-engineered sensing platform, where the moiré superlattice creates a configurable surface potential for molecular control. Here we present a periodically modulated landscape in bilayer MoS₂ by twist-angle tuning, and use it for molecular trapping and selective sensing. The native 54 meV moiré potential confines aromatic molecules (e.g., rhodamine 6G, R6G; methylene blue, MB) at AA-stacking sites. Introducing extended vacancies deepens confinement to 238 meV, enhancing adsorption. Twist angle enables band alignment with molecules, driving charge-transfer resonances. This integrated design, moiré potentials, defect-enhanced trapping and band-aligned charge transfer, synergistically amplifies Raman signals, achieving single-molecule sensitivity down to 10^-20 M. Importantly, the platform exhibits molecule-specific selectivity: R6G is optimally detected at 10° and 50° bilayer MoS₂, while MB responds at 15° and 45°, demonstrating twist-angle encoding of molecular recognition. Our twisted MoS₂ with extended vacancies establishes a moiré system as a versatile platform for selective molecular sensing.