Over the past decade, perovskite solar cells have travelled an amazing way towards high efficiency. However, a major roadblock remaining is the operational stability, while achieving technological maturity and proving real-world stability is crucial to gain trust among investors. In that sense, it is of high interest to be able to predict the operational lifetime, which needs to be in the range of years or decades, within an experimentally reasonable timeframe. Yet, peculiarities of perovskite solar cells’ ageing behaviour lead to severe difficulties in translating the results of indoor tests to their outdoor counterpart. In particular, transient processes cause diverse results among different ageing tests.
Here, for the first time, we show a complete set of constant illumination indoor testing, cycled illumination indoor testing and real-world outdoor testing on equal in-house devices. Exemplarily, we compare two different types of perovskite solar cells, in which only the hole-transport layer is varied. Despite this small change, the devices show distinctly different transient behaviour. In either case, the commonly used constant illumination experiments fail to predict the outdoor behaviour of the cell. Yet, we observe a good correlation between the cycled illumination test and the outdoor behaviour of one of the two solar cells, while this is not the case for the other system. This result highlights the urge for further research on how to perform meaningful accelerated indoor tests to predict the outdoor lifetime of perovskite solar cells.