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.