EPFL scientists put perovskite through its paces

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A team of researchers at the École Polytechnique Fédérale de Lausanne (EPFL) has devised a new method for assessing the stability of perovskite solar cells which they say removes several of the drawbacks inherent to lab and outdoor testing of such devices.

The team’s approach, described in the paper Performance of perovskite solar cells under simulated temperature-illumination real-world operating conditions, published in Nature Energy, is centered on simulating realistic irradiation and temperature conditions in a laboratory, which the researchers say eliminates the need for an encapsulant and so allows them to eliminate failure mechanisms related to that element, rather than in the perovskite material itself.

Weather data from a nearby station in Lausanne was used to reproduce real-world temperature and irradiance profiles from specific days in a laboratory, enabling the scientists to quantify the device’s performance under realistic conditions.

Degradation recovered after dark

Their findings showed the cells were not dramatically affected by the ‘real world’ temperature and irradiance swings and that while some degradation of cell efficiency occurred during the ‘day’, it was recovered after dark. That could be seen as evidence stability problems which have held perovskites back from commercial development for so long have been solved. However, many of those hurdles to mass production related to cells coming into contact with moisture, an occurrence which was not discussed in the EPFL results.

The institute has been a leader in investigating the performance of perovskite cells and in developing standard measurements for various aspects of them, including aging and degradation.

“The term ‘stability’ is used very broadly and assessed in various ways, meaning different groups are running different races,” reads the research paper’s abstract. “For the application, only energy yields that can be achieved under real-world, long-term operation matter.”