LaAlO3:Mn4+ as Near-Infrared Emitting Persistent Luminescence Phosphor for Medical Imaging: A Charge Compensation Study

Abstract

Mn4+-activated phosphors are emerging as a novel class of deep red/near-infrared emitting persistent luminescence materials for medical imaging as a promising alternative to Cr3+-doped nanomaterials. Currently, it remains a challenge to improve the afterglow and photoluminescence properties of these phosphors through a traditional high-temperature solid-state reaction method in air. Herein we propose a charge compensation strategy for enhancing the photoluminescence and afterglow performance of Mn4+-activated LaAlO3 phosphors. LaAlO3:Mn4+ (LAO:Mn4+) was synthesized by high-temperature solid-state reaction in air. The charge compensation strategies for LaAlO3:Mn4+ phosphors were systematically discussed. Interestingly, Cl−/Na+/Ca2+/Sr2+/Ba2+/Ge4+ co-dopants were all found to be beneficial for enhancing LaAlO3:Mn4+ luminescence and afterglow intensity. This strategy shows great promise and opens up new avenues for the exploration of more promising near-infrared emitting long persistent phosphors for medical imaging.

Temperature dependent persistent luminescence: Evaluating the optimum working temperature

“…The excitation wavelengths and integrated emission ranges were applied as shown in Table 2. These excitation and emission ranges are in line with literature reports 6,10,18,40–43 .…”

“…Several widely studied and commercialized persistent luminescent compounds (Glo.Tech.Intl. ), namely Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ (SMSO), SrAl 2 O 4 :Eu 2+ , Dy 3+ (SAO), Sr 4 Al 14 O 25 :Eu 2+ , Dy 3+ (SAO25), CaAl 2 O 4 :Eu 2+ , Nd 3+ (CAO), Y 2 O 2 S:Eu 3+ , Mg 2+ , Ti 4+ (YOS), CaS:Eu 2+ , Dy 3+ (CaS) were used as well as the LaAlO 3 :Mn 4+ , Na + (LAO) phosphor synthesized in our lab 18,35 .…”

“…As a result, much effort has been spent to develop LPPs from the NIR emitting family. Up to now, there are growing numbers of persistent phosphors for NIR emission, with the representative ones including Zn 3 Ga 2 Ge 2 O 10 :Cr 3+ 2 , LiGa 5 O 8 :Cr 3+ 12–14 , La 3 Ga 5 GeO 14 :Cr 3+ 15,16 , LaAlO 3 :Mn 4+ 17,18 . The experimental material research has allowed the improvement of the LPPs in order to obtain a sufficiently strong and long lasting luminescence.…”

Synthesis and Biomedical Applications of Lanthanides-Doped Persistent Luminescence Phosphors With NIR Emissions

“…As mentioned in the first part, PLPs are ideal materials for bioimaging since they can effectively avoid spontaneous fluorescence of biological tissues (Abdukayum et al, 2013 ; Li et al, 2020 ). However, the PLPs synthesized by traditional high-temperature reactions lack appropriate modifiable group on the surface (Du et al, 2017 ). Moreover, the persistent luminescence of PLPs will diminish over time in vivo , and they cannot be effectively reactivated by UV light due to the limited penetration of UV.…”

Visible and Near-Infrared Emission in Ba3Sc4O9:Bi Phosphor: An Investigation on Bismuth Valence Modification

“…Near-infrared (NIR) luminescence materials have attracted extensive attention in the fields of bio-imaging, food composition analysis, and night-vision technologies for their noninvasive and rapid detection characteristics. − Therefore, numerous NIR phosphors have been explored by introducing rare-earth ions (Pr 3+ , Tm 3+ , Nd 3+ , and Yb 3+ ) or transition-metal ions (Cr 3+ and Mn 4+ ) into inorganic host materials. − However, the sharp line emission of rare-earth ions with 4f–4f parity-forbidden transition suspends their applications in broad-band light source. Meanwhile, Cr 3+ - and Mn 4+ -doped materials are hard to achieve emission in a NIR II window (1000–1700 nm), which exhibits a higher contrast ratio and deeper penetrability to biotissues due to the reduced autofluorescence and scattering .…”