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Dasom Kim Photo Credit: Jorge Vidal/Rice University |
Atoms in crystalline solids sometimes vibrate in unison, giving rise to emergent phenomena known as phonons. Because these collective vibrations set the pace for how heat and energy move through materials, they play a central role in devices that capture or emit light, like solar cells and LEDs.
A team of researchers from Rice University and collaborators have found a way to make two different phonons in thin films of lead halide perovskite interact with light so strongly that they merge into entirely new hybrid states of matter. The finding, reported in a study published in Nature Communications, could provide a powerful new lever for controlling how perovskite materials harvest and transport energy.
To get a specific light frequency in the terahertz range to interact with phonons in the halide perovskite crystals, the researchers fabricated nanoscale slots ⎯ each about a thousand times thinner than a sheet of cling wrap ⎯ into a thin layer of gold. The slots acted like tiny metallic traps for light, tuning its frequency to that of the phonons and thus giving rise to a strong form of interaction known as “ultrastrong coupling.”