Microscopic Characterization of Polarization-Type Potential-Induced Degradation of Perovskite Solar Cells

Potential-induced degradation (PID) presents a significant challenge to the long-term reliability of perovskite solar cells (PSCs) in commercial applications. Research on PID in PSCs is still in its early stages, the polarization-type PID (PID-P) remains poorly understood. In this study, we used advanced electrical and mechanical microscopic techniques to investigate the underlying mechanisms of PID-p in PSCs. After 100 hours of PID stress, the devices experienced severe performance loss, with efficiency reduced to just 20.9% of its initial value. This degradation was primarily driven by a decrease in short-circuit current and fill factor, while the open-circuit voltage remained relatively stable. Our findings reveal that the accumulation of Na+ at the glass/film interface triggers the formation of an electron inversion layer at the perovskite's bottom, leading to performance decline. Surface potential mapping confirmed the presence of this electron inversion layer, while nanomechanical mapping revealed Young's modulus increased at the grain boundaries after PID exposure. These unstable interface conditions compromised the hole-transport layer/perovskite junction, resulting in increased leakage current and higher interface recombination. Our study sheds light on the formation and impact of the electron inversion layer in PID-p, offering new insights into the PID mechanisms of PSCs.