Researchers Make One-Atom-Thin Electrical Generator

Super-thin material could turn clothing into a power source

A Sample Of Molybdenum Disulfide
Researchers from the Georgia Institute of Technology and Columbia Engineering have made the first experimental observation of piezoelectricity and the piezotronic effect in an atomically thin material, molybdenum disulfide (MoS2). Shown is a sample of the material that was tested as part of the research. The material could be the basis for unique electric generator and mechanosensation devices that are optically transparent, extremely light, and extremely bendable and stretchable.Rob Felt/Georgia Tech

How thin can an electrical generator possibly be? Thanks to a study published yesterday in Nature, the answer is about as thin as possible. Using molybdenum disulfide, researchers from the Georgia Institute of Technology and Columbia Engineering proved that a layer just an atom thick can generate an electric charge.

The key to this charge is piezoelectricity, or the electric generated from pressure, usually from stretching or compressing a material. With the molybdenum disulfide, the researchers found that it generated electricity in layers that were an odd number of atoms thick, including layers as thin as one atom.

A single monolayer flake strained by 0.53% generates a peak output of 15 mV and 20 pA, corresponding to a power density of 2 mW m−2 and a 5.08% mechanical-to-electrical energy conversion efficiency. In agreement with theoretical predictions, the output increases with decreasing thickness and reverses sign when the strain direction is rotated by 90°.

Squeezing Charges From Material
This is a cartoon showing positive and negative polarized charges are squeezed from a single layer of atoms of molybdenum disulfide (MoS2), as it is being stretched.Lei Wang/Columbia Engineering

Single-atom-thick materials are exciting, because they open up new possibilities for materials science, like making tiny transistors. Molybdenum disulfide is particularly interesting because of its potential as a thin transistor incorporated into other materials. Now that scientists have shown atom-thin layers of it can generate electricity, future designers and engineers might incorporate it into very small and self-powering machines. Because it needs to stretch to generate power, it might not work well on a tablet-like device, but imagine it built into a shoe with a display that can tell how many steps you've made that day.