Cr3 + -Cr3+ ion pair and crystal field engineering in magnetoplum type NIR-emitting phosphor for spectroscopic applications

The development of tunable broadband near-infrared (NIR) fluorescent materials with excellent luminescent properties is still a challenge for the next generation of intelligent NIR light sources. Here, a series of Cr 3+ doped magnetoplum type NIR phosphors were prepared by the high-temperature solid-state method. Their luminescent properties and the methods to broaden the luminescence bandwidth were discussed in detail. In BaAl 12 O 19 : Cr 3+ phosphor, Cr 3+ -Cr 3+ ion pair was constructed based on heavily doped Cr 3+ ions, so as to broaden its spectral emission range. With the increase of Cr 3+ doping concentration, the full width at half maximum (FWHM) of BaAl 12 O 19 : Cr 3+ sample increased from 18.5 nm to 93.7 nm. Furthermore, the crystal field environment of Cr 3+ ions in BaAl 12 O 19 : Cr 3+ phosphors was changed by cationic substitution (Sr 2+ substituted Ba 2+ ion site). The FWHM of NIR emission increases from 49.37 nm to 123.78 nm, and the internal quantum efficiency (IQE) increases from 65.6 % to 76.2 %, with good thermal stability ( I 373 K / I 298 K = 77.3 %). An intense NIR emission of 31.3 mW at 100 mA is produced by the phosphor-converted light-emitting diode (pc-LED), exhibiting a photoelectric efficiency of 15.3 %.