Tunable luminescence via Cr3+–Yb3+/Nd3+ energy transfer in Cr3+ and Yb3+/Nd3+ coactivated NIR phosphors for non-destructive analysis

Abstract

For efficient near-infrared (NIR) emitters, tuning their luminescence properties is important for their extended optical applications. A fundamental study of garnet-type inorganics has led to the development of a new NIR phosphor Y₃ScAl₄O₁₂:Cr³⁺ (YSAO:Cr³⁺), exhibiting emission in the range of 600 to 950 nm, an internal quantum efficiency (IQE) of 84.01%, and good thermal stability at 423 K (89.7% of that at room temperature). Doping with Yb³⁺/Nd³⁺ ions helps achieve an efficient energy transfer from the Cr³⁺ to Yb³⁺/Nd³⁺ ions with excellent thermal stability. NIR pc-LED devices prepared using YSAO:Cr³⁺,Yb³⁺ and YSAO:Cr³⁺,Nd³⁺ can achieve high NIR output powers of 46.37 and 42.82 mW at 100 mA and photoconversion efficiencies of 20.27 and 18.84% at a driving current of 20 mA, respectively. Furthermore, the NIR pc-LED package demonstrated excellent capability for penetrating biological tissues, effectively distinguishing between pork, chicken, and beef. These results suggest that the phosphors can be utilized for non-destructive monitoring applications.