Researchers use ‘trick of the light’ to eliminate flaws in next-gen solar cells

Australian researchers have developed a new method of using light to detect imperfections materials, that is set to help improve performance and quality of the next-generation solar cells.

The research has been published in the journal Nano Energy, and was led by Australian scientists at Monash University and the CSIRO who hope it will lead to improved quality control in the production of next-generation perovskite solar cells.

The technique uses photoluminescence to reveal faults within solar cells. Using this process, the electrons within solar cell materials are “excited” by being exposed to light. When the electrons return to their normal state, light is emitted and reveals the structures that have formed within the solar cell material.

The researchers have developed a technique that exposes perovskite solar cells with blue light, and then using a camera, captures the infrared light that is then emitted from the material, revealing its internal structures.

The new technique allows for imperfections that are not visible with the naked eye to be revealed, and for researchers to monitor the performance of the cells under different operating conditions.

Imperfections within solar cells can significantly reduce the efficiency at which it converts light into electricity, and commercial solar cell producers have been looking for easy ways to identify and eliminate such imperfections.

The researchers said that the light trick would help to significantly speed up the process of identifying faults within solar cells and allow manufacturers to adjust their manufacturing processes.

“Using this technique, we can rapidly identify a whole range of imperfections,” Monash University researcher Dr Kevin Rietwyk said.

“We can then figure out if there are enough of them to cause a problem and, if so, adjust the manufacturing process to fix it. It makes for a very effective quality control method.”

This light technique is a common method for monitoring the quality of silicon based solar cells. The researchers at Monash University have developed a new approach that allows the same technique to be used in next-generation perovskite solar cells.

The research was supported through the ARC Centre of Excellence in Exciton Science, and included collaboration with the Wuhan University of Technology and the CSIRO Energy hub, and the researchers are optimistic that their new approach is saleable and has the potential to be deployed in a commercial manufacturing environment.

“This research shows clearly that the performance of perovskite solar cell devices influenced by the number of small imperfections in the cells themselves,” Co-author and Monash University researcher professor Udo Bach said.

“Using light modulation to find these flaws is a quick and robust way to solve the problem – and one that should work on any level of production.”

While silicon based solar cells currently dominate the global market for solar cells, perovskite solar cells have been touted as a potential pathway to cheaper and more adaptable solar cells.

The efficiency of perovskite solar cells has increased dramatically in recent years as researchers refine the technology, and are approaching similar conversion efficiencies as those achieved by silicon cells.

However, researchers and manufacturers have faced challenges in preventing degradation in the perovskite materials, which can dramatically reduce performance.

Researchers at the Australian National University recently set a new world record for “tandem” solar cell efficiency, which stacks a perovskite solar cell on top of a silicon solar wafer, boosting efficiency to levels approaching 30 per cent.

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