Photoinduced Phase Segregation in Mixed Halide Perovskites: Mechanisms, Suppression Strategies, and Device Performance Optimization

For mixed-halide perovskite solar cells, the phenomenon of photoinduced phase segregation (PIPS) and its derivative effect of uneven spatial ion distribution within the material have induced a series of adverse consequences. Since the discovery of this phenomenon, although substantial research progress has yielded significant achievements in this field, a systematic logical organization among different research methodologies or models of PIPS remains scarce. To address this gap, this review systematically traces the evolution of PIPS research─from fundamental thin-film properties to its impact on the operational performance of complete solar cells. Through synthesizing prevalent models and corresponding solutions, it endeavors not only to summarize the intrinsic logic within each model framework but also to rigorously analyze the interrelationships among distinct models. Simultaneously, diverging from the substantial body of research focused on analyzing PIPS-affected thin films, this work systematically examines and integrates the implications of the PIPS phenomenon within complete solar cell devices and the corresponding suppression strategies implemented at the device level. This perspective bridges critical mechanistic gaps identified in current experimental investigations while underscoring the imperative for co-optimizing phase stability and defect passivation in next-generation perovskite photovoltaics.