Improved luminescence and afterglow emission from Mn2+/Si4+ co-doped AlN by combustion synthesis method

Abstract

An orange-red emitting Mn2+/Si4+ co-doped AlN phosphor was prepared by an efficient combustion synthesis method. Phase identification and structure characterization were performed using powder X-ray diffraction (XRD) and refined by the Rietveld method. Luminescence and afterglow properties of the AlN-based phosphors such as photoluminescence spectra (PL), CIE values, afterglow decay curves, thermoluminescence glow curves (TL) were systematically studied. Using the Tanabe-Sugano diagram, the Racah parameters B, C, and crystal field splitting parameter Dq of as-prepared phosphor were calculated to be 812 cm−1, 2168 cm−1, and 780 cm−1, respectively. The luminescence intensity and afterglow time were increased, respectively, by about 1.1 and 2.2 times after 3% Si4+ co-doping. Particular attention was paid to study the mechanism of Si4+ co-doping on improving luminescence properties using a combination of the above-mentioned method and X-ray photoelectron spectroscope (XPS). Two hypothetical stress cancellation and charge rebalance effects due to Si4+ co-doping were discussed. Besides, it was found a shallower trap level (0.56 eV, compared to 0.84 eV for those without Si4+ co-doping) was formed after the co-doping of Si4+, which results in enhanced afterglow performance.