Lead Complex Ion‐Mediated Conversion: A Facile Route to High‐Performance Zeolite‐Confined CsPbI ₃ Luminescent Composites with Uniform Morphology, Elevated Loading and Quantum Yield

ABSTRACT CsPbI 3 perovskite quantum dots (QDs) are promising for deep‐red light‐emitting diodes (LEDs), but their instability and low luminescence efficiency hinder practical application. Here, we develop an innovative lead complex ion‐mediated conversion strategy to encapsulate CsPbI 3 QDs with high‐loading and uniform size into hierarchical TS‐1 zeolite, abbreviated as CPI@TS‐1(NaI) composite. This method resides in the in situ generation of water‐soluble [PbI 4 ] 2− complex ions from PbI 2 and excess I − inside the zeolite nanospace, which elevates the local precursor concentration and modulates the nucleation and growth kinetics of CsPbI 3 QDs, enabling a high loading rate of 77.2%. The released I − ions from the conversion of [PbI 4 ] 2− into CsPbI 3 QDs can passivate the iodine vacancy defects, raising the photoluminescence quantum yield (PLQY) of QDs to 45.1% and significantly improving luminescent stability against heat, moisture, and continuous irradiation. Practical validation shows that the CPI@TS‐1(NaI)‐based phosphor‐converted WLED device reaches a maximum luminous efficacy of 65.2 lm W −1 and retains over 98% of its initial luminance after 24 h of continuous operation. Incorporating CPI@TS‐1(NaI) effectively remedies the red spectral deficiency and increases the rendering index (CRI) to 86.2. This work offers a new route to fabricate stable, high‐efficiency perovskite‐based phosphors for advanced lighting and display applications.