Mn5+-doped BaAl2O4, Ba3Al2O6, and Ba7Al2O10 phosphors emitting in the second near-infrared biological window

In recent years, NIR-II-type fluorophores with emission wavelengths within the 1000–1700 nm range have garnered widespread attention in the field of bioimaging due to their high tissue penetration ability. Here, Mn-doped BaAl2O4, Ba3Al2O6, and Ba7Al2O10 with NIR-II-type luminescence were synthesized by solid-phase or liquid-phase methods. Confirmed by XPS and EDS analysis, Mn is found uniformly distributed in the structure in the valence state of + 5. The optimal doping concentration of Mn5+ in the three matrices was analyzed by PLE and PL spectroscopy. In addition, the samples exhibit a wide excitation range spanning from 600 to 900 nm, coupled with a narrow emission band peaking between 1150 and 1200 nm. As both the excitation and emission wavelengths have excellent penetration capabilities in biological tissues, the synthesized fluorescent phosphors in this study hold potential for meaningful applications in the realm of fluorescence imaging.