Broadband short-wave near-infrared-emitting phosphor MgNbO:Cr for -LED applications.

Broadband short-wave near-infrared (NIR) phosphor-converted light-emitting diodes (-LEDs) have been attracting keen interest for miniature NIR spectroscopy, while still lacking sufficient novel broadband NIR-emitting phosphors. Herein, we report a novel MgNbO:Cr polycrystalline phosphor with a broad NIR emission band centered at 970 nm and a large full-width at half-maximum of approximately 155 nm under excitation of bluish-green light at around 515 nm. The optimized phosphor MgNbO:1%Cr features a high internal quantum efficiency (IQE) of ∼85.5% and a moderate external QE of 25.2%. The fluorescence properties determined by two distorted hexa-coordination octahedral sites ( [MgO] and [NbO]), low crystal field strength (/ ∼ 1.65), and Cr-doping concentration were systematically investigated for comprehensive understanding of photophysical mechanisms. Besides, this broadband NIR phosphor MgNbO:Cr exhibits a moderate thermal quenching of 21.4%@373 K for -LED application. An NIR -LED self-built by combining the optimal phosphor with a commercial cyan of ∼515 nm exhibits an NIR output power increase from 3.19 to 11.38 mW as the drive current is varied from 40 to 220 mA. With the help of this prototype -LED device, multiple applications were successfully performed to clearly recognize blood vessel distributions in the human finger, penetrate a plastic cap, and distinguish multi-color text. Undoubtedly, further development of such broadband short-wave NIR-emitting phosphors will make novel -LED devices for significant applications in biomedical imaging, nondestructive safety detection, intelligent identification, .