From Sunrise to Sunset: Unraveling Metastability in Perovskite Solar Cells by Coupled Outdoor Testing and Energy Yield Modelling

Perovskite-based solar cells exhibit peculiar outdoor performance which is not yet fully understood. The results of outdoor tests may contain hidden, but valuable information that cannot be fully extracted from measurements alone. One such phenomenon is the effect of nighttime degradation and the subsequent light-soaking recovery, which can take from a few hours in the morning up to the entire day. In this work, long-term outdoor monitoring is combined with energy yield modeling to qualitatively and quantitatively investigate the effect of light-soaking recovery in both single junction and tandem perovskite-based devices. Following the novel methodology presented in this study, it is observed that the light-soaking effect depends not only on the daily irradiation but also on the device temperature, and it can be described using a simple empirical formalism. Incorporating this dependency into the energy yield model results in an excellent agreement between the simulated and the measured outdoor data, which allows to perform long-term prediction studies. The model estimates that the light-soaking metastability effect decreases the attainable annual energy yield by up to ≈5% for the studied single junction devices, and for tandems by up to ≈3%, depending on the geographical location, and even more for non-optimal device orientation.