Accelerated aging replicates spatially non-uniform degradation modes observed in outdoor-aged perovskite solar cells

Identifying real-world degradation modes in perovskite solar cells (PSCs) and reproducing them through accelerated aging tests are accomplishments that remain elusive, and this limits progress toward commercialization. Here, we identify three coexisting, spatially non-uniform degradation modes in PSCs following 20 months of outdoor operation: copper corrosion, edge patterns, and phase segregation. By varying light intensity (1 and 2.3 suns) and electrical bias (at the maximum power point [MPP] or open-circuit [OC] conditions) as key stressors, we reproduce and accelerate all three mechanisms. Furthermore, we demonstrate how the interplay of stressors can alter the manifestation of each degradation mode. Among them, phase segregation is the most spatially dominant mode outdoors, and it results in irreversible, micrometer-scale domains. Nevertheless, external stimuli induce optoelectronic changes in these domains that we associate with the metastability observed outdoors. This work links real-world degradation modes to accelerated aging tests, reveals their spatial signatures, and points toward mechanism-targeted acceleration.