Defect and Crystal Field Engineering Enables High Efficiency and Anti-Thermal Quenching in Cr3+ Doped Rigid Garnet Phosphors for Multifunctional Optoelectronics
Near-infrared (NIR) phosphors with high quantum efficiency (QE) and thermal robustness are critical for phosphor-converted light-emitting diodes (pc-LEDs). Here, a Cr3+-activated Lu2BaAl4SiO12 (LBASO) garnet phosphor is engineered via chemical unit cosubstitution of [Ba2+-Si4+] for [Lu3+-Al3+] in Lu3Al5O12 (LuAG), inducing a strong crystal field that yields NIR emission at 705 nm. The optimized LBASO:0.07Cr3+ exhibits an internal quantum efficiency (IQE) of 84.82% and external quantum efficiency (EQE) of 46.02%. Notably, it demonstrates anti-thermal quenching (ATQ) with 126.03% of its initial intensity at 498 K under 442 nm excitation, attributed to a wide band gap, weak electron-phonon coupling, defect trap energy levels, high structural rigidity, and optimized electron population distribution. A NIR pc-LED fabricated with this phosphor achieves an output power of 134.99 mW and photoelectric conversion efficiency of 11.4% at 100 mA drive current. These results underscore the potential of LBASO:Cr3+ for applications in plant lighting, night vision, and nondestructive analysis.