Linking Double Inductance in Impedance Spectroscopy to Ionic Losses in Perovskite Photovoltaics

Beyond recombination processes, a major contributor to ion-induced efficiency losses in perovskite solar cells is charge collection failures, associated with a pronounced reduction in short-circuit current density, the appearance of current–voltage hysteresis with steep slope around 0 V, and negative capacitance effects in impedance measurements. This work presents a physical model that differentiates degradation pathways induced by mobile ions, enabling a unified interpretation of electrical responses. A central feature in the multifaceted low-frequency impedance region is the double inductor response, serving as a fingerprint of ion-driven degradation with combined action in recombination and charge collection. Extracted time constants reveal how their interplay reshapes impedance responses and current–voltage curves during aging, which serve as unequivocal markers of the dominant factors affecting operational stability. Our results establish the double-inductor behavior as a key spectroscopic signature of device degradation, adding a new feature to the catalogue of anomalous phenomena in perovskite devices.