Fluoride ions add layer of defence to perovskite solar cells

Perovskite is low cost, easy to produce and almost as efficient as silicon-based solar cells. This has helped stimulate research into the material that has seen its efficiency rise from under four per cent in 2009 to over 24 per cent, which is close to traditional silicon cells. Tandem cells, which combine silicon and perovskite cells, achieve an efficiency of over 28 per cent.

Perovskite does, however, contain a number of defects due to the nature of the material and the way it is manufactured. Over time, vacancies in the atomic structure of the metal halide trigger the degradation of the perovskite under the influence of moisture, light and heat.

Now, researchers from Eindhoven University of Technology, DIFFER (Dutch Institute for Fundamental Energy Research), Peking University and University of Twente have discovered that a small amount of fluoride increases the stability of the material and the solar cells significantly. The solar cells are claimed to retain 90 per cent of their efficiency after 1,000 hours of operation at extreme testing conditions. The findings are published in Nature Energy.