Ionic Losses and Gains in Perovskite Solar Cells: Impact on Efficiency and Stability

Mobile ionic charges can significantly affect the performance of perovskite solar cells (PSCs) in terms of power conversion efficiency (PCE), as well as stability if their density changes over time. However, assigning performance losses during aging to ionic losses requires a reference point which is independent of the mobile ion density. In this Viewpoint we discuss, using drift-diffusion simulations, how the mobile ion density can affect the PCE obtained from a fast J–V scan when the preconditioning voltage does not match the voltage at which the ionic space charge vanishes. Depending on device properties, this misalignment can induce relative performance gains thanks to mobile ions and lead to an overestimation of the ionic loss. Taking into account the interplay between ion density and competing recombination pathways is crucial for the loss and degradation analysis of PSCs.