Realizing Tunable Long Persistent Luminescent in Novel Cu2+‐Doped NaGaO2 for Multi‐Level Information Storage and Encryption

Abstract Anti‐counterfeiting and encryption are key technologies for information transmission in modern society. However, most optical materials offer only a single fixed response mode, limiting their security level in advanced anti‐counterfeiting applications. Exploring efficient and tunable long persistent luminescent (LPL) phosphors is urgently demanded and highly meaningful. In this work, a dual‐site occupancy strategy is innovatively reported via Li + doped NaGaO 2 : Cu 2+ (NGO: Cu 2+ /Li + ) phosphors for enhancing LPL properties. To be specific, Cu 2+ initially occupies both Na and Ga sites in NaGaO 2 , producing orange–yellow LPL at 585 nm and near‐infrared (NIR) emission at 712 nm, respectively. Furthermore, the introduction of Li + will occupy the Na + sites, attenuating the NIR emission and increasing the defect density of the oxygen‐deficient states, which results in enhanced LPL intensity and prolonged afterglow time. Significantly, the obtained NGO:Cu 2+ /Li + exhibits multi‐emission modes with dynamic change of LPL time (10–20 min). More importantly, the NGO: Cu 2+ /Li + has great potential applications in multi‐level information storage and encryption.