Australian research improves scope, efficiency of PV light sensitizers

From pv magazine Australia

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

The ARC Centre of Excellence in Exciton Science and Monash University researchers published their findings in Nanoscale. Their research marks a breakthrough, because previous light sensitizers had been ineffectual with silicon solar cells, which are currently the most commonly available type of PV 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.

Countering a customary conclusion, the researchers found that 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,” said researcher Laszlo Frazer.

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.