Australian research improves the scope and efficiency of PV light sensitisers

The research examines the ideal formation of quantum dots – man-made nanocrystals 100,000 times thinner than a sheet of paper – to be used as light sensitisers, absorbing infrared and visible light and transferring it to other molecules. The endgame is to enable new types of solar panels to capture more of the light spectrum and generate more electrical current.

Published in the journal Nanoscale, the findings from the ARC Centre of Excellence in Exciton Science and Monash University researchers marks a breakthrough because previous light sensitisers had been ineffectual with silicon solar cells, which currently the most commonly available type of photovoltaics technology.

Working with lead sulfide quantum dots sized to the ideal dimensions and density thanks to their algorithm’s simulations, researchers increased the light sensitiser’s efficiency and extended its compatibility to nearly all existing and planned solar cell technology.

When it comes to quantum dot size, bigger isn’t necessarily better

Countering a customary conclusion, researchers found larger quantum dots aren’t necessarily better. Rather, a far more complicated cocktail of conditions need to be considered to increase efficiency, as well as practical constraints on quantum dot size.

Importantly, the researchers noted the near-infrared part of sunlight at the Earth’s surface has a complicated structure, influenced by water in the atmosphere and the sun’s heat. This means the colour of the quantum dot must be tuned to match the peaks of sunlight, just as a musical instrument might be adjusted to a certain pitch.

“This whole thing requires understanding of the sun, the atmosphere, the solar cell and the quantum dot,” author Dr Laszlo Frazer said.

Next steps

Following their findings, the researchers now need to design and create emitters which will transfer energy from the optimised quantum dot sensitisers most effectively.

“This work tells us a lot about the capturing of light,” Laszlo said.

“Releasing it again is something that needs a lot of improvement. There’s definitely a need for multidisciplinary contributions here.”

“More work needs to be done on building the solar cell prototypes with these sensitisers (and hopefully with the suitable emitters), and to test them,” author Benedicta Sherrie of Monash University said.

“I hope this research will eventually allow society to rely more on photovoltaic solar energy that is not only efficient, but also affordable.”

The researchers’ algorithm is free to access, published in the journal Nanoscale.