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

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.