Atom-Thin Piezoelectric Generator

Oct-17-14 A new atom-thin material that generates energy when bent could find its way into wearable electronics and medical devices—and proves things are a bit different in the atomic world.

The 2D material is made of a layer of molybdenum disulfide (MoS2),which had been previously predicted to have piezoelectric capabilities. However, MoS2 has to be precisely arranged in order to unleash its energy-generating power. To create the generator, the team created an odd number of layers of MoS2 flakes on a flexible substrate and then flexed the material in a specific direction. Both the odd number of layers and the direction of the flex are key to the generator's functionality; an even number of layers will cancel out the piezoelectric effect and flexing the material in a different direction will cause the output voltage to reverse sign.

According to Jess Hone, co-leader of the team, “This is the first experimental work in this area and is an elegant example of how the world becomes different when the size of material shrinks to the scale of a single atom.”

Large image: Positive and negative polarized charges are squeezed from a single layer of atoms as it is being stretched.

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