Unity Quantum Yield of High‐Entropy Quantum Dots Composited With Photonic Crystals for Information Encryption

ABSTRACT The escalating demand for advanced anti‐counterfeiting and information encryption technologies has driven the exploration of luminescent materials with high quantum yield, multi‐level encoding capability, and long‐term stability. This study extends the high‐entropy paradigm to I‐III‐VI quantum dots (QDs) for the first time, successfully synthesizing CuZnCrGaSe/ZnSe/ZnS (CZCrGSe/ZnSe/ZnS) core/shell/shell high‐entropy QDs via a one‐pot nucleation strategy combined with stepwise hot‐injection shell coating. By optimizing reaction parameters and composition ratios, combined with a precisely designed ZnSe/ZnS double shell for efficient defect passivation, the QDs achieve an emission wavelength of 540 nm and a record‐breaking photoluminescence quantum yield (PLQY) of 100%, which stands as the highest PLQY reported for alloy QDs to date. Integrating these high‐performance QDs into stimulus‐responsive photonic crystals (PCs) yields dual‐mode nanocomposite films capable of exhibiting two reversible optical states: structural color and fluorescent color. The luminescent properties of high‐entropy QDs synergistically modulate with the photonic bandgap of the PCs, enabling multidimensional information encryption. This functionality was validated through a visual encoding/decoding system capable of secure binary code conversion. This work achieves a significant breakthrough in the luminescent performance of alloy QDs and provides a novel strategy for developing eco‐friendly, high‐performance optical encryption materials.