The World's Thinnest Solar Cells Have Been Created With Just An Atom Or Two


Researchers at the Vienna University of Technology have succeeded for the first time in creating a diode made of tungsten diselenide.

Experiments show the material may be used to create ultrathin flexible solar cells, an atom or two thick. Even flexible displays could be possible.

The scientists wanted something thin such as the new material graphene which consists of only one atomic layer of carbon atoms. However, it isn’t suitable for solar cells.

“The electronic states in graphene are not very practical for creating photovoltaics,” says Professor Thomas Mueller of the Photonics Institute at the Vienna University of Technology.

He and his team started to look for other materials which, similar to graphene, can be arranged in ultrathin layers but with better electronic properties.

The material of choice was tungsten diselenide which is one layer of tungsten atoms connected by selenium atoms.

The layer is so thin that 95% of the light passes through.

But a tenth of the remaining five per cent, which are absorbed by the material, is converted into electrical power.

A larger portion of the available light can be used if several of the ultrathin layers are stacked on top of each other.

“We are envisioning solar cell layers on glass facades, which let part of the light into the building while at the same time creating electricity,” says Thomas Mueller.

Standard solar cells are mostly made of silicon but they are bulky and inflexible.

“A big advantage of two-dimensional structures of single atomic layers is their crystallinity. Crystal structures lend stability,” says Thomas Mueller.

The results of the experiments at the Vienna University of Technology are published in the journal Nature Nanotechnology.

The research field is extremely competitive. In the same issue of the journal two more papers are published in which very similar results are shown.

Researchers at MIT in the US and at the University of Washington have also discovered the great advantages of tungsten diselenide.

A microscope photograph of a sample, of the ultrathin layers made of Tungsten and Selenium, connected to electrodes.

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