CaY2ZrScAl3O12:Cr3+—an efficient and thermally stable garnet phosphor for high-performance NIR LEDs

High-quantum efficiency (QE) and superior luminescence thermal stability NIR phosphors are indispensable for producing advanced NIR pc-LEDs. Despite this, the broadband NIR phosphor peaking around ∼780 nm often falls short in performance. Our research focused on developing a series of CaY2ZrSc1−xAl3O12:xCr3+ (CYZS:xCr3+) NIR phosphors, where x ranges from 0.01 to 0.20 mol, through strategic chemical substitutions of [Ca2+–Zr4+–Sc3+] for [Y3+–Al3+–Al3+] in Y3Al5O12:Cr3+ (YAG:Cr3+). This modification yielded broadband NIR emissions centered at ∼780 nm when stimulated with blue light. Remarkably, the optimized CYZS:0.08Cr3+ phosphor demonstrated exceptional QE values (IQE/EQE = 78.4%/31.6%), alongside outstanding thermal stability, maintaining around 84.3% of its original intensity at 423 K. Finally, we fabricated a high-performance NIR pc-LED device by combining CYZS:0.08Cr3+ with a blue LED chip (455 nm). The integrated NIR pc-LED boasts an impressive output power of 69.7 mW at 150 mA, along with a high photoelectric conversion efficiency of 22.2% when operating at 10 mA. Our findings indicate that CYZS:xCr3+ phosphors harbor promising applications in advancing NIR pc-LEDs.