Performance monitoring and stability testing of perovskite solar cells

With high power conversion efficiencies already achieved in perovskite solar cells (PSCs), research is moving towards improving the stability of those devices. The primary focus of this thesis is on the stability analysis of perovskite-based solar cells under realistic operating conditions. The results of long-term outdoor monitoring are combined with indoor characterization results and systematically analysed to evaluate the operational performance and long-term outdoor behaviour of PSCs. Compared to conventional photovoltaics (PV), PSCs can exhibit a various, often high-magnitude, reversible changes in device performance. Two indoor ageing setups that enable the characterization of those effects are presented: the developed white LED (WLED), for characterization of single junction devices, and optimized bichromatic LED (BCLED), used for the testing of tandem solar cells. Seasonal operation is analysed and discussed for single-junction perovskite solar cells. Despite the good summer-to-summer stability of the devices, the seasonality observed in the Berlin climate is significantly more pronounced compared to silicon PV. We explain and interpret this behaviour by separating and explaining the different contributing factors: solar spectrum, device temperature, maximum power point tracking losses, and metastability effects. The metastability effects are observed in various perovskite compositions, but their dynamics and magnitude can vary. Analysis of how the magnitude of metastability differs in devices that share the same structure but use different hole transport layers (HTLs) is presented. To qualitatively and quantitatively investigate the effect of light-soaking effect we combined long-term outdoor monitoring results with energy yield modelling for both single junction perovskite and perovskite-silicon tandem solar cells. The presented long-term outdoor data for the lab-scale PSC devices, demonstrates the potential of PSC technology to reach the operational lifetime requirements of current commercialized PV technologies. However, it is important to improve our understanding of the processes behind their unique real-world behaviour to achieve accurate data interpretation and energy yield forecasting.