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

Abstract

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 CaY₂ZrSc_1−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.