Low‐Coordination Crystallographic Lattice Engineering to Discover Ce3+‐Activated Ultra‐Wide Visible‐to‐Near‐Infrared Luminescent Materials

Abstract Development of ultra‐broadband visible‐to‐near‐infrared (VIS‐NIR) luminescent materials is a challenging but rewarding endeavor, as they are highly desirable for a number of applications in photonics, optoelectronics, and biological sciences. Nevertheless, to date, rare earth‐doped phosphors that can be efficiently excited by blue light and produce broadband emission in the VIS‐NIR regions remain scarce. In this study, a series of Ce 3+ ‐doped Ba 3 M 4 O 9 (M = Sc, Lu, Y) broadband luminescent materials are designed based on low‐coordination crystallographic lattice engineering. Among these materials, Ba 3 Y 4 O 9 :Ce 3+ produces a continuous ultra‐wide VIS‐NIR emission (λ em = 660 nm) in the range of 500–950 nm under 410 nm light excitation. This emission wavelength is the longest among those observed in Ce 3 ⁺‐doped oxide materials. Structural refinement, theoretical calculation, and spectral analysis demonstrate that this VIS‐NIR broadband emission is attributed to the occupying multiple distorted octahedral lattice sites by Ce 3+ in Ba 3 Y 4 O 9 . Several strategies are employed to enhance the luminescence intensity and thermal stability of this material, including the use of carbon paper coating, the incorporation of co‐solvents, and the addition of GeO₂ or ZrO₂. Furthermore, the as‐prepared materials demonstrate multifunctional applications in white light‐emitting diodes (WLED), night vision, and fluorescent thermometers. This study offers insights into the design of Ce3+‐doped ultra‐wide VIS‐NIR light‐emitting materials.