Enhanced near-infrared luminescence and thermal stability in Cr3+-Activated Y2CaAl4SiO12 phosphors: Towards high-performance NIR light sources

Cr³⁺ activated broadband near-infrared (NIR) phosphors exhibit tremendous potential for the phosphor-converted light-emitting diodes (pc-LEDs). Unfortunately, they still suffer from drawbacks such as low efficiency, and poor thermal stability. Herein, we have successfully developed a series of broadband NIR-emitting phosphors Y₂CaAl₄SiO₁₂:Cr³⁺ with good luminescence performance. Under 435 nm light excitation, the Y₂CaAl₄SiO₁₂:0.05Cr³⁺ phosphor shows broadband NIR emission in the 700–1100 nm range with a full width at half maximum (FWHM) of 159 nm. The significant impacts of Cr³⁺ doping concentration, fluxing agent, sintering atmosphere and host lattice composition were demonstrated in detail, some effective strategies which can enhance the luminescence performance of Cr³⁺ were successfully acquired. More excitingly, the optimized phosphor possesses outstanding thermal stability and satisfactory internal quantum efficiency of 96 %, the emission intensity can maintain as high as 89.8 % at 423 K of that at room temperature, surpassing most of reported Cr³⁺-doped NIR phosphors. The promising applications in night vision and biological tissue penetration were successfully validated for the NIR phosphor. The findings and simple strategies proposed in this research may pave a way for the development of high-quality broadband NIR emitting phosphors.