Dynamic Screening and the Chemical Inductor of Perovskite Solar Cells: From J-V Transients to Impedance Spectroscopy.

The operation of metal halide perovskite solar cells is governed by the interplay between electronic transport and recombination processes strongly modulated by ionic dynamics. We present a unified framework that disentangles the photocurrent into distinct ionic-electronic conductivity pathways, incorporating recombination, polarization, and charge-collection effects. Using simplified dynamic models, we describe how electric-field screening and slow ionic relaxation shape the hysteresis of the photocurrent. From the nonlinear differential equations, we derive the corresponding impedance response and show that the characteristic low-frequency "double inductor" feature arises from two separate mechanisms: ion-controlled recombination and ionic screening of the internal electric field. This approach offers a general route to connect transient photocurrent phenomena with impedance signatures, providing new tools to identify and classify degradation pathways in perovskite solar cells.