ANU researchers go round the twist with latest ultra-thin solar discovery


Scientists at The Australian National University (ANU), which received $3.6 million in funding from the Australian Renewable Energy Agency (ARENA) in January as part of the Australian Centre for Advanced Photovoltaics Infrastructure project, have discovered something interesting about the potential of ultra-thin 2D materials. 

Back in 2019, Hieu Nguyen and PhD candidate Mike Tebyetekerwa demonstrated the maximum potential of ultra-thin 2D materials to generate electricity using sunlight for the first time. This is to say, materials thin as a single atom capable of harvesting solar energy, a technology that could revolutionise the solar industry as well as many other industries besides. 

Last week, the two ANU scientists published a study in “Cell Reports Physical Science” in which they demonstrate a curious and exciting observation – that the ability of these ultra-thin materials to convert sunlight into electricity can be controlled by “twisting” the angle between two layers of the material. 

By themselves, a monolayer of the material can’t do much, they have to be paired in what is called “heterobilayers” in such a way that the “close interlayer spacing…of their similar hexagonal crystal symmetry” means they can be tuned with a”wide degree of freedom”.

Tebyetekerwa, the lead author of the paper, said this discovery of “tuneable twistronics” opens up exciting opportunities. 

“This study essentially provides a bit of a how-to guide for engineers,” Tebyetekerwa said. “We’re looking at 2D materials that have just two atom-thin layers stacked together. This unique structure and large surface area make them efficient at transferring and converting energy.”

The potential of this technology is virtually limitless, and certainly not limited to solar cells, but also mobile phones, sensing devices etc. The materials, which are hundreds of thousands times thinner than a human hair, so thin they make Kate Moss look like Jabba the Hutt, could be coated on all types of surfaces, from phone screens to car windshields, enabling the device to power itself. 

“It’s an exciting new field,” said Nguyen, “simply twisting the two ultra-thin layers can dramatically change the way they work. The key is to carefully select the matching pair and stack them in a particular way.” 

There is still a lot of research to do on this ultra-thin, ultra-lightweight, transparent materials capable of holding high-voltage solar cells, but these researchers are proving that you don’t have to go completely round the twist to make great innovations, just a little twist is enough. 

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