Dual‐Site Cooperative Regulation Strategy Enables High‐Performance Near‐Infrared Luminescence and Wireless Communication Applications of Cr 3+ Activated Garnet Phosphors

Abstract Broadband near‐infrared (NIR) phosphors have attracted significant attention as next‐generation intelligent NIR light sources. However, simultaneously achieving blue‐light excitation, long‐wavelength emission (>810 nm), and the synergistic optimization of high thermal stability and quantum efficiency remains a critical challenge. In this study, a dual‐site cooperative regulation strategy is successfully employed to construct Cr 3+ ‐activated garnet‐type NIR phosphors [Ca 2+ y Gd 1‐ y ]Zr 2 [Al 3‐ y Ge y ]O 12 : 0.01Cr 3+ , realizing high‐performance broadband NIR luminescence and multifunctional applications. The cooperative substitution at A‐site (Ca 2+ /Gd 3+ ) and C‐site (Al 3+ /Ge 4+ ) induces multidimensional regulation, including full width at half maximum (FWHM) broadening (ΔFWHM = 35 nm/305 cm −1 ), emission peak redshift (47 nm), and luminescence enhancement (2.58 times). The [CrO 6 ] octahedral distortion caused by dodecahedral expansion and tetrahedral contraction, along with electron paramagnetic resonance (EPR) variations, elucidates the intrinsic mechanisms of FWHM broadening and emission redshift. The dual‐site cooperative regulation effectively widens the material bandgap while significantly enhancing structural rigidity, thereby achieving excellent thermal stability (93.8%@423 K). Based on the differential response characteristics of this phosphor to acidic environments, a Morse code‐based encryption system is successfully developed. A near‐infrared phosphor‐converted light‐emitting diode (pc‐LED) is fabricated, achieving nondestructive testing, near‐infrared imaging, night vision, and stable wireless optical communication. This study provides an innovative design strategy for developing high‐performance near‐infrared phosphors.