Laser-Controlled\nInformation Releasing and Hiding\nBased on Perovskite Phosphors

Laser-active interference with high confidentiality and\nconvenience\nopens up a cutting-edge path for releasing and hiding key targets;\nhowever, its development still faces enormous challenges owing to\nthe difficulty of concealing objects. Herein, a novel conceptual design\nfor laser-controlled information release and hiding (LIRH) is proposed\nand successfully realized. Cs<sub>2</sub>NaInCl<sub>6</sub>:Er<sup>3+</sup>, Yb<sup>3+</sup> (CNIC:Er, Yb) perovskite microcrystal is\nadopted as a carrier for LIRH implementation, exhibiting excellent\nup-conversion (UC) emission under NIR (980 and 1530 nm) irradiation\ndue to its ultralow phonon energy. The fluorescence intensity crossover\nand outstanding photon output capacity are revealed in comparison\nwith Er<sup>3+</sup>/Yb<sup>3+</sup> codoped and Er<sup>3+</sup> single-doped\nCNIC phosphors under different laser sources, and the obvious difference\nin quantum yields (QY) under 980 and 1530 nm excitation provides theoretical\npossibility for LIRH. More importantly, the obtained LIRH features\nhigh stability at temperatures up to 413 K, showing good adaptability\nin various potential scenarios. Moreover, CNIC:Er, Yb is further combined\nwith polyacrylonitrile (PAN) polymer to form fluorescent fibers with\nexceptional crystal stability and composite flexibility, thus making\nthe LIRH code a reality based on perovskite composite phosphors. The\nlaser-active invisibility offers an innovative idea for LIRH, further\nextending the application of LIRH in the field of information encryption,\nwhich has promising prospects in information safety, advanced anticounterfeiting,\nand smart responsive materials.