The Roles of Ion Migration on Perovskite Solar Cell Operational Stability at Various Illumination Intensities

Abstract

Monitoring the stability of perovskite solar cells (PSCs) under operational conditions is crucial for their development. This study integrates maximum power point (MPP) tracking with quasi in-situ electrochemical impedance spectroscopy at successive intervals to elucidate the temporal evolution of degradation mechanisms in PSCs. The gradual losses in photocurrent, photovoltage, and fill factor during MPP tracking were attributed to alterations in recombination processes, kinetic constants, shunt pathways, and series resistances, each manifesting at distinct phases of the PSC stability assessment. Notably, these variations correlated with a progressive increase in ionic density and mobility within the perovskite layer, as evidenced by a shift in the low-frequency ionic response and a 0.13 eV reduction in ionic activation energy. This apparent enhancement in ionic conductivity was more pronounced under illuminance levels below 1000Lx, predominantly affecting shunt resistance and leading to significant implications for indoor photovoltaic performance. The reported methodology offers a straightforward, non-destructive, and effective means to augment conventional PSC stability analyses across various lighting conditions.