Performance of Perovskite Solar Cells under Real-World Temperature-Illumination Variations in the Lab
Konrad Domanski a, Brian Carlsen b, Essa Alharbi b, Michael Gratzel b, Anders Hagfeldt b, Wolfgang Tress b
a Fluxim AG, CH, Katharina-Sulzer-Platz, 2, Winterthur, Switzerland
b Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
Oral, Konrad Domanski, presentation 004
Publication date: 25th November 2019

After reaching 20% efficiency, research in perovskite photovoltaics has shifted from a race for efficiency to a race for stability. For efficiency, the standard test conditions (STC) set the rules for the race. However, the term stability is used very broadly and assessed in various ways, meaning different groups are running different races. [1] For the application, however, only energy yields that can be achieved under real-world, long-term operation matter. [2]

In this work [3], we characterize and analyse the performance of 20% efficient perovskite solar cells under simulated ambient conditions based on real temperature and irradiance data of 27 selected days during a year in Sion, Switzerland. Working in a controlled lab environment, a much more reliable and systematic collection of data can be carried out, avoiding parasitic failure mechanisms, and weather conditions of an arbitrary location and time of year can be emulated without physical presence outdoors.

We find that the perovskite solar cell shows a low decrease of efficiency with elevated temperature and low light intensity, maintaining almost optimum values for dominant ambient conditions. Therefore, the resulting year-averaged efficiency (energy produced/total illumination energy) is close to the STC value. The overall energy yield is influenced by reversible degradation (<2% a day), delivering the highest performance in the morning, and ~10% permanent degradation, observable during the year.

Finally, we compare the perovskite with 22% efficient silicon heterojunction devices. Whereas the maximum-power-point voltage of these is differently affected by the weather conditions, the current scales linearly with light intensity for both, which is particularly important when considering 2-terminal perovskite-silicon tandem cells.

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