In-depth Characterization and Simulation Approach for the Understanding of In- and Outdoor Degradation of Perovskite Solar Cells

Perovskite solar cells (PSCs) have recently shown, on top of their very high power-conversion efficiency (PCE), a remarkable improvement in stability. Despite this, very few studies focus on the long-term testing of these devices. The exact mechanisms governing degradation are yet to be discovered and there is still a lack of a consensus on which accelerated tests can be used to accurately mimic stresses in real-life field deployment. To address these issues, this work uses several of the International Summit on Organic Photovoltaic Stability (ISOS) protocols, combined with an electrical characterization and simulation toolbox, to compare outdoor field testing of PSCs with indoor accelerated tests. The study reveals that long-term outdoor exposure mainly leads to the degradation of the perovskite absorber layer. On the contrary, the very popular dark thermal stress test affects the perovskite/electron transport layer (ETL) interface. It is also shown that testing thermal stability under light and under maximum power point tracking (MPPT) is the closest accelerated test to mimic outdoor exposure, with similar degradation features observed. Overall, this study highlights some of the key degradation modes occurring in PSCs, while showing the importance of diversified testing to better comprehend and improve the stability of these devices.