Perovskite nanocrystals as fluorescent sensors for Fe³⁺: Mechanistic insights and emerging trends

Perovskite nanocrystals (PNCs) have emerged as powerful fluorescent platforms for the selective and sensitive detection of Fe³⁺ ions due to their defect-tolerant electronic structure, high photoluminescence efficiency, and tunable optoelectronic properties. This review provides mechanistic insights into the diverse quenching pathways governing Fe³⁺ sensing, including photoinduced electron transfer, inner filter effects, cation exchange, aggregation dynamics, magnetic polaron formation, and oxidative surface processes. By correlating structural characteristics with optical responses, we highlight how composition engineering, surface chemistry, and dimensionality influence sensing performance across lead-based and lead-free systems. Emerging trends such as ratiometric emission, core–shell stabilization, hybrid organic–inorganic interfaces, and dopant-mediated enhancements are discussed as promising strategies toward improved accuracy, environmental stability, and biocompatibility. Recent advances in film-based and solid-state perovskite sensors further underscore their potential for integration into portable, low-cost detection platforms. To the best of our knowledge, this work represents the first review article specifically focused on Fe³⁺ ion sensing using PNCs, offering a unified perspective on mechanistic foundations and future directions. Overall, this work consolidates current progress while identifying challenges and opportunities for developing next-generation perovskite fluorescent sensors capable of reliable Fe³⁺ monitoring in environmental, biological, and industrial settings.