ACS Energy Letters Viewpoint
Viewpoint published in ACS Energy Letters on ionic effects in perovskite solar cells!
ACS Energy Letters is a journal by the American Chemical Society that publishes breakthrough findings on energy materials, storage and conversion.
In our invited viewpoint article we discuss the interplay between ionic and electronic properties, and specifically the characterization of ionic losses (or gains) by comparing fast and slow J–V scans, which is a great way to analyze the role of mobile ions in power conversion efficiency (PCE) and degradation. We look at simulated degradation scenarios where both the ion density and defect recombination rate change over time, showing how the PCE difference between a fast preconditioned J-V scan and a slow stabilized one does not necessarily directly correspond to an ionic loss. The accuracy of this approach depends on the amount of ionic accumulation at the precondition voltage used for the fast J-V scan. The preconditioned PCE would ideally be independent from the mobile ion density, such that it would approximate the equivalent 'ion-free' performance of the device. For this, positive and negative ionic charge should be mostly compensated in the bulk at the precondition voltage, such that the net ionic space charge vanishes. We discuss how preconditioning above the 'ion-free' voltage may affect the analysis, and how mobile ions are not necessarily detrimental for the performance of all PSCs in general. These points should be considered to elucidate the role of mobile ions on PSC device stability.
Read the full paper here (open access).