The hysteresis-free behavior of perovskite solar cells from the perspective of the measurement conditions

We investigate how far the hysteresis-free behavior of perovskite solar cells can be reproduced using particular pre-conditioning and measurement conditions. As there are currently more and more reports of perovskite solar cells without J-V hysteresis it is crucial to distinguish between genuine performance improvements and measurement artifacts. We focus on two of the parameters that influence the dynamic J-V scans, namely the bias scan rate and the bias poling voltage, and point out measurement conditions for achieving a hysteresis-free behavior. In this context we discuss the suitability of defining a hysteresis index (HI) for the characterization of dynamic J-V scans. Using HI, aging effects are also investigated, establishing a potential connection between the sample degradation and the variation of the maximal hysteresis on one hand, and the relaxation time scale of the slow process on the other hand. Pre-poling induced recombination effects are identified. In addition, our analysis based on sample pre-biasing reveals potential indications regarding two types of slow processes, with two different relaxation time scales, which provides further insight regarding ionic migration.