Multi-site occupancy high-efficient CaY2ScZrAl3O12:Cr3+,Ce3+ phosphors for application in broadband NIR pc-LEDs

Abstract

With an increasing demand for highly efficient and easily valuable near-infrared (NIR) illumination in many fields, such as night vision, agriculture and medical sectors, it is of great importance to develop new NIR light sources. Here, we have successfully synthesized a novel broadband NIR phosphor by incorporating Cr³⁺ ions into the CaY₂ScZrAl₃O₁₂ (CYSZA) matrix. Under excitation at 455 nm, CYSZA:0.11Cr³⁺ exhibits a broad emission ranging from 650 to 1150 nm and has excellent thermal stability (98% at 375 K). Time-resolved spectroscopy (77 K) and peak fitting analysis reveal that the broad NIR emission is attributed to the Cr³⁺ ions occupying the [ScO₆] and [ZrO₆] sites and forming two luminescent centers. The incorporation of Ce³⁺ ions into the CYSZA:0.11Cr³⁺ phosphor further improves the luminescence efficiency, resulting in a significant increase in internal quantum efficiency (IQE) from 66% to 88%. The outstanding properties of CYSZA:Cr³⁺,Ce³⁺ phosphors make them promising candidates when combined with blue chips for applications in night vision and non-destructive testing technology.