electrons tagged posts

Image of one of the graphene-based devices Xu and colleagues worked with. Credit: Lei Wang

In traditional light-harvesting methods, energy from 1 photon only excites 1 electron or none depending on the absorber’s energy gap. The remaining energy is lost as heat. But a new article describe an approach to coax photons into stimulating multiple electrons. Their method exploits some surprising quantum-level interactions to give one photon multiple potential electron partners.

Wu and Xu in UW’s Dept of Materials Science & Engineering and the Det of Physics, made this surprising discovery using graphene.
The researchers took a single atom layer of graphene and sandwiched it between 2 thin layers of boron-nitride. Electrons do not flow easily within boron-nitride so it is an insulator.

When the g...

Electroluminescence from vertically stacked GaN–Al2O3–MoS2–Al2O3-graphene heterostructures.

1st demo of electroluminescence from multilayer molybdenum disulfide, or MoS2, a discovery that could lead to a new class of materials for making LEDs. In its single-layer form, Mos2 is optically active, meaning that it emits light when electric current is run through it or when it is shot with a nondestructive laser. Multilayer molybdenum disulfide, by contrast, is easier and less expensive to produce, but it is not normally luminescent. In the new study, Duan and Dehui, created the 1st multilayer device that shows strong luminescence when electrical current is passed through it.

“It was rather surprising for us to discover that similar vertical devices made of multilayer MoS2 somehow showed ...