Broadband Short-Wave Infrared-Emitting MgGa₂O₄:Cr³⁺, Ni²⁺ Phosphor with Near-Unity Internal Quantum Efficiency and High Thermal Stability for Light-Emitting Diode Applications

Blue InGaN chip-pumped short-wave infrared (SWIR) emitters have aroused tremendous attention and shown emerging applications in diverse fields such as healthcare, retail, and agriculture. However, discovering blue light-emitting diode (LED)-pumped SWIR phosphors with a central emission wavelength over 1000 nm remains a significant challenge. Herein, we demonstrate the efficient broadband SWIR luminescence of Ni²⁺ by simultaneously incorporating Cr³⁺ and Ni²⁺ ions into the MgGa₂O₄ lattice, with Cr³⁺ as the sensitizer and Ni²⁺ as the emitter. Because of the strong blue light absorption of Cr³⁺ and high energy transfer efficiency to Ni²⁺, the obtained MgGa₂O₄:Cr³⁺, Ni²⁺ phosphors show intense SWIR luminescence with a peak wavelength at 1260 nm and a full width at half maximum (FWHM) of 222 nm under the excitation of blue light. The optimized SWIR phosphor presents an ultra-high SWIR photoluminescence quantum efficiency of 96.5% and outstanding luminescence thermal stability (67.9%@150 °C). A SWIR light source has been fabricated through a combination of the prepared MgGa₂O₄:Cr³⁺, Ni²⁺ phosphor and a commercial 450 nm blue LED chip, delivering a maximum SWIR radiant power of 14.9 mW at 150 mA input current. This work not only demonstrates the feasibility of developing broadband high-power SWIR emitters using converter technology but also presents new insights into the importance of SWIR technology.