Stability of 2D Halide Perovskite From External Stimuli

ABSTRACT Within the halide perovskite family, dimensionally confined two‐dimensional (2D) halide perovskite has gained remarkable attention being more stable alternatives compared to their three‐dimensional (3D) counterparts. After more than a decade of intensive research, the community now faces a critical question: to what extent are 2D halide perovskites truly stable? Although they are widely regarded as “more stable” than their 3D counterparts, it demands a deeper and more systematic understanding of their stability landscape under various external perturbations. Prolonged light irradiation, elevated temperatures, exposure to polar solvents, and moisture can all compromise the structural and optical integrity of 2D halide perovskites, leading to phase transformations, morphological evolution, halide segregation, and eventual degradation. The mechanistic origins of these responses are multifaceted and needs a summarization. This growing need motivates us to present a focused and comprehensive overview dedicated exclusively to the stability of 2D halide perovskites. In this perspective, we provide a unified survey of how 2D halide perovskites respond to external stimuli, detailed consequences and highlight underlying mechanisms to emphasize the stability aspect of 2D halide perovskite. We aim to orient researchers toward rational design and stabilization strategies with prospects to advancing the development of durable 2D halide perovskite‐based optoelectronic technologies.