PhD student Elham Gholizadeh working in the Molecular Photonics Laboratories at UNSW Sydney.  Credit: UNSW/Exciton Science.
Original Published Date: 
Wednesday, July 22, 2020

Full article issued by the ARC Centre of Excellence in Exciton Science.

ARC-supported researchers in Australia, in collaboration with colleagues in the United States, have made a breakthough in light conversion that has potential future implications for solar photovoltaics, biomedical imaging, drug delivery and photocatalysis.

The research team, led by Elham Gholizadeh at The University of New South Wales (UNSW), has been able to ‘upconvert’ low energy light into high energy light, which can be captured by solar cells, in a new way, with oxygen the surprise secret ingredient.

While the approach’s efficiencies are relatively low and more work is needed to achieve commercialisation, the research is an exciting development, according to ARC Future Fellowship recipient, Professor Tim Schmidt from the ARC Centre of Excellence in Exciton Science and UNSW.

“The energy from the sun is not just visible light,” Professor Schmidt explains. “The spectrum is broad, including infrared light which gives us heat and ultraviolet which can burn our skin.

“Most solar cells, charge-coupled device (CCD) cameras and photodiodes (a semiconductor that converts light into electrical current) are made from silicon, which cannot respond to light less energetic than the near infrared. This means that some parts of the light spectrum are going unused by many of our current devices and technologies.”

To extend the range of sensitivity of these devices, and potentially increase the efficiency of solar cells, the team have ‘upconverted' the light, turning low energy light into more energetic, visible light which can excite silicon. The researchers used semiconductor quantum dots (nanoscale man-made crystals) to absorb the low energy light, and molecular oxygen to transfer light to organic molecules.

Contributing researcher, Professor Jared Cole from RMIT University, says: “What’s interesting is that often without oxygen, lots of things work well. And as soon as you allow oxygen in, they stop working. But now, not only have we found a way around it, suddenly it helps us.”

“This is only an early demonstration, and there’s quite a lot of materials development needed to make commercial solar cells, but this shows us it’s possible,” Professor Schmidt says.

Photo credit: 

Image: PhD student Elham Gholizadeh working in the Molecular Photonics Laboratories at UNSW Sydney. Credit: UNSW/Exciton Science.