Researchers at Eindhoven University of Technology, research centre Differ, University of Twente and Peking University found a way to make perovskite solar cells more resilient, by adding a protective layer of fluoride.

Perovskite is an attractive materials to make solar cells. It’s cheap, easy to make and almost as profitable as silicium, a common resource for solar cells. A downside of perovskite, however, is that the material degrades quickly under the influence of moisture, light and heat, clearly a fatal flaw for solar panels.

The researchers experimented with a new type of perovskite by adding a small amount of fluoride during the production process of the material. Like in toothpaste, the fluoride ions become a protective layer around the crystal, so no harmful errors can spread.

The fluoride probably works so well, compared to other halogens, because the fluoride ions are so small and have high electro negativity. The latter characteristic ensures that the ions can made a strong connection with other elements within the perovskite and form a stable protective layer.

After a thousand hours under extreme conditions, the perovskite were still 90 per cent efficient. But while that is a major stride for perovskite, solar panels need to have 85 per cent efficiency after 10 to 15 years, so there is still a lot of work to be done.