A 2-degree twist creates a nanoscale grid that traps light energy at room temperature
You may have once tried taking a close-up picture of a computer screen and noticed a wavy, rippling effect. This optical effect occurs whenever two fine, repeating grids overlap and slightly misalign, such as when the pixel grid of your camera's sensor overlaps with the pixel grid of the screen.
A research team from the University of Twente, in collaboration with scientists from Utrecht, Brazil, and Japan, discovered a method to create a nanoscale grid that traps light energy at room temperature. The key to their discovery lies in the overlap of two sheets of molybdenum disulfide, a thin semiconductor crystal. By rotating one sheet by just 2 degrees relative to the other, the researchers formed a repeating pattern that altered the material's interaction with light.
This pattern occurs every 9 nanometers, which is roughly the width of a human hair. When light interacts with semiconductors, it can create pairs of particles called excitons, which determine how the material absorbs and emits light. The new study, published in Nature Physics, revealed that the moiré pattern can trap excitons at specific locations, allowing for controlled light manipulation in a programmable grid.
This breakthrough was made possible through a novel technique that mapped the nanoscale exciton distribution at room temperature and under real device conditions. The research opens up possibilities for designing highly precise light-absorbing and electrical components.
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