Boosting Excitonic Emission in 2D Multiple Quantum Well Superlattices by Plasma-Assisted Electrochemical...

Scalable fabrication of multiple quantum-well (MQW) superlattices via layer-by-layer stacking of two-dimensional (2D) materials remains challenging. Here, we propose a plasma-assisted electrochemical intercalation strategy to overcome this limitation. By intercalating 1-ethyl-3-methylimidazolium (EMIM⁺) cations into multilayer molybdenum disulfide (MoS₂), followed by oxygen plasma intercalation, we achieve large-area (∼100 μm) MQW superlattices with hundreds of active layers. This approach enhances MoS₂ photoluminescence (PL) by 2 orders of magnitude, with the PL quantum yield (PLQY) increasing with both excitation power and thickness. The enhancement arises from interlayer-decoupling-induced bandgap directness and electron extraction induced by oxygen plasma, effectively suppressing charge transfer between heterointerfaces. Our findings provide a scalable route for fabricating quasi-MQW superlattices, opening new avenues for photophysics research and next-generation optoelectronics.