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

Abstract 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.