Understanding Ion‐Related Performance Losses in Perovskite‐Based Solar Cells by Capacitance Measurements and Simulation

Understanding the behavior of mobile ions in perovskite‐based solar cells (PSCs) is crucial for improving their performance and stability, which belong to the key hurdles in advancing this technology toward commercialization. This study explores the role of mobile ions in PSCs using the comprehensive technology computer‐aided design model which is extended to simulate the frequency‐dependent capacitance ( C–f ) of PSCs. It is compared with equivalent circuit approaches showcasing the validity and advantages of full device modeling. By combining the simulation of full measurement procedures with C–f and J–V measurements on experimental test structures, the observed C–f characteristics can be quantitatively related to performance losses in scan‐time‐dependent J–V curves, both originating from ion diffusion. With this combined analysis, insights can be provided on the physical origin and interpretation of the different C–f plateaus caused by the displacement of ions. Finally, the C–f characteristics of PSCs under illumination and the impact of band alignment and recombination at the perovskite interface are investigated. Experimental PSCs with and without electron‐transport layer passivation are fabricated, showing a good agreement between the simulated and measured C–f and pointing toward a lower surface recombination for the passivated PSC. This study shows how drift‐diffusion modeling helps to characterize and interpret capacitance‐based data.