Light Emission Reveals Two Scales of Disorder in Twisted 2D Semiconductors
A theoretical study examined twisted MoSe2/WSe2 heterostructures, where overlapping light-emission peaks make disorder hard to analyze. The approach identified two hidden types of disorder: one spread over larger areas and another tied to tiny defects. Mapping these patterns through photoluminescence could improve how scientists assess ultrathin materials for optical and quantum devices.
Stacking MoSe2 and WSe2 layers with a slight rotational offset creates a periodic moiré landscape that modifies light emission. The resulting photoluminescence has many overlapping peaks, making it hard to trace each peak to a specific cause.
Katsunori Wakabayashi at MANA/NIMS devised a theoretical route that follows simpler spectral measures—such as peak positions and mean emission energy—across a surface. Tested against earlier MoSe2/WSe2 correlation data, it pointed to broad, micrometer-scale disorder and smaller defect-related trapping sites. The paper appeared in Physical Review Research.
Better ways to infer disorder in ultrathin semiconductors may help researchers and manufacturers assess material quality, potentially improving reproducibility of light-emitting devices, sensors, and quantum components. This could benefit labs, semiconductor firms, and end users relying on more consistent optical technologies, though practical gains depend on validation and adoption.