LaMgGa₁₁O₁₉:Cr³⁺,Ni²⁺ as Blue-Light Excitable Near-Infrared Luminescent Materials with Ultra-Wide Emission and High External Quantum Efficiency

Highly efficient luminescence material covering near-infrared (NIR) I (700-1000 nm) and II (1000-1700 nm) is of great importance for phosphor-converted NIR light-emitting diodes (pc-LEDs) light sources. The lack of ultra-wide emission NIR luminescent materials that can be excited by cheap blue-LEDs, suspends the applications of NIR pc-LEDs. Ni2+-activated phosphor usually gives an NIR-II region emission, however, it presents low quantum efficiency due to poor absorption in blue light region. Here, a blue-LED-excitable (400-480 nm) LaMgGa11O19(LMG):Cr3+,Ni2+ NIR-emitting phosphor is reported. Significantly, by constructing energy transfer from Cr3+ to Ni2+, it demonstrates an ultra-wide NIR emission from 650 to 1600 nm, and greatly improves external quantum efficiency (EQE) from 2% to 53%. Besides, the weakened exchange coupling of Ni2+-Ni2+ pairs leads to an abnormal blue-shift of Ni2+ emission with increasing temperature. The fabricated NIR pc-LED gives a high output power of 8 mW at 20 mA with the photoelectric efficiency of 14%, which favors potential applications in night-vision technology, medical applications, non-destructive analysis, and spectroscopic analysis. This exploration of Cr3+-Ni2+ co-doped strategy for realizing high-performance NIR-emitting phosphor provides novel and effective design insights into developing more ultra-broadband NIR pc-LEDs based on cheap blue LEDs.