Broadband NIR emission with excellent thermal stability for SrLaGaO4:Cr3+ phosphor

Phosphor-converted near-infrared light-emitting diodes (pc-NIR-LEDs) exhibit unique advantages over traditional NIR light sources, shifting the research focus toward high-performance NIR phosphors. The transition metal Cr 3+ ion serves as an ideal NIR activator, displaying highly sensitive emission characteristics that are strongly influenced by the primary crystal field environment. However, reports on Cr 3+ doping in SrLaGaO 4 (SLG) with a disordered structure as the host material remain limited. This study focuses on the synthesis of SrLaGa 1-x O 4 :x%Cr 3+ phosphors, where x ranges from 0.2 to 1.2. The optimized SLG:Cr 3+ phosphor demonstrates ultra-wideband NIR emission spanning from 650 to 1250 nm under excitation at 429 nm. Notably, the material exhibits superior thermal stability (ΔE = 0.35 eV, E G  = 5.17 eV), retaining 66.55 % emission intensity at 423 K. Detailed optical analysis reveals that the emission from Cr 3+ -Cr 3+ ion pairs during the ( 4 A 2 , 4 T 2 → 4 A 2 , 4 A 2 ) transitions results in non-uniform broadening of the optical transition, which is one of the key factors contributing to its superior NIR performance. The output power of the pc-NIR-LED based on the SLG 0.99 :1.0 % Cr 3+ and 430 nm chip reached 0.418 W@150 mA. The results suggest that the novel SLG:Cr 3+ phosphor holds great prospects for advancing NIR lighting technology.