Dopant and compositional modulation triggered long-wavelength ultra-broadband and tunable NIR emission in MgO: Cr3+ phosphor for NIR spectroscopy applications

Efficient ultra-broadband near-infrared (NIR) phosphors with long-wavelength (λmax > 850 nm) and wide full width at half-maximum (FWHM, >200 nm) have sparked tremendous interest, demonstrating their immense potential in NIR spectroscopy technology. Nevertheless, the development of NIR spectroscopy technology suffers from the restricted capability to efficiently emit the ultra-broadband NIR light. Herein, the synergetic enhancement strategy of heterogeneous substitution and compositional modulation was applied to create a novel Cr3+ doped long-wavelength ultra-broadband MgO: Cr3+, Ga3+ phosphor, which exhibited a long-wavelength ultra-broadband NIR emission (λmax = 850 nm) covering the range of 650–1300 nm on the electromagnetic spectrum with the FWHM of more than 200 nm under the excitation of 468 nm light. Furthermore, the tunable NIR emission from 818 nm to 862 nm with an optimized quantum efficiency of 30% was accomplished by the Ga3+ ions substitution and Cr3+ ions modulation. The phosphor exhibited remarkable thermal stability up to 100 °C, remaining 83% of the integrated emission intensity at room temperature. A prototype of the NIR phosphor-converted LED (pc-LED) demonstrated that the novel MgO: Cr3+, Ga3+ phosphor possessed a relatively strong NIR output power (15.05 mW at 100 mA driven current) with a photoelectric conversion efficiency of 5.53%, which is impressive compared with other Cr3+-doped long-wavelength ultra-broadband phosphors. This work not only proposes a novel long-wavelength ultra-broadband NIR phosphors with industrialization and great application prospect in night vision but highlights a synergetic enhancement strategy to effectively boost the performance of long-wavelength ultra-broadband NIR pc-LED light sources.