Researchers at RMIT University (Melbourne, Australia) have shown that surface acoustic waves (SAWs) on an atomically thin layer of molybdenum disulphide (MoS2) can controllably modulate the substance's photoluminescence.1 The effect occurs because the SAWs introduce mechanical strain in the MoS2, which has been shown to affect photoluminescence. Another way to view the phenomenon is that the SAWs are "dragging" electrons around.
The finding has implications for photonic and optoelectronic devices made from 2D materials.
"In this work, we use these ripples which occur on a crystal surface and couple it into a material that is a few atomic layers thick (2D material), which causes a change in its electronic properties," says Sumeet Walia, one of the researchers. "As the surface acoustic waves are turned on and off or increased and decreased in intensity, the change in electronic properties of the 2D materials follows the same pattern."
According to researcher Amgad Rezk, the SAW-based tunability did not result in any structural or compositional change in the MoS2.
The many possible uses include highly efficient solar cells, smart windows, consumer imaging sensors suitable for low-light photography, and sensors for fluorescence imaging.
The work was supported by the Australian Research Council and undertaken at RMIT's MicroNano Research Facility.
REFERENCE:
1. Amgad R. Rezk et al., Advanced Optical Materials (2015); doi: 10.1002/adom.201500034