Dual-Mode Long-Lived Luminescence of Mn²⁺-Doped Nanoparticles for Multilevel Anticounterfeiting

Abstract

Luminescent nanoparticles with dual-mode long-lived luminescence are of great importance for their attractive applications in biosensing, bioimaging, and data encoding. Herein, we report the realization of up-and downconversion emission of Mn 2+ dopants in multilayer nanoparticles of NaGdF 4 :Yb/Tm@NaGdF 4 :Ce/Mn@NaYF 4 upon excitation at 980 and 254 nm, respectively. The dual-mode emission of the Mn 2+ dopants at 531 nm have a long-lived lifetime up to ∼30 ms as a result of the spin-forbidden optical transition of Mn 2+ within the 3d 5 configuration. After ceasing steady excitation at the two wavelengths, the long-lived feature of Mn 2+ luminescence allows a longer persistent time than lanthanide emissions, thereby enabling the ease of data decoding by a cell phone camera under a burst mode. The long-lived green upconversion emission also permits the generation of a long green tail emission upon dynamic excitation at 980 nm. These attributes make the as-prepared Mn 2+ -doped multilayer nanoparticles particularly attractive for multilevel anticounterfeiting.

Triple‐Mode Emissions with Invisible Near‐Infrared After‐Glow from Cr3+‐Doped Zinc Aluminum Germanium Nanoparticles for Advanced Anti‐Counterfeiting Applications

“…In recent years, novel luminescent materials integrating multimode emissions have been proposed. [ 11–14 ] For example, Liu et al. reported multilevel anti‐counterfeiting materials based on NaGdF 4 :Yb/Tm@NaGdF 4 :Ce/Mn@NaYF 4 core/shell nanoplates which integrated the advantages of single‐mode DCPL and multicolor tunable UCPL in the same materials.…”

“…reported multilevel anti‐counterfeiting materials based on NaGdF 4 :Yb/Tm@NaGdF 4 :Ce/Mn@NaYF 4 core/shell nanoplates which integrated the advantages of single‐mode DCPL and multicolor tunable UCPL in the same materials. [ 12 ] Lin and co‐workers prepared carbon dots‐based materials with simultaneous DCPL, UCPL, and room‐temperature phosphorescence (RTP) triple‐mode emissions. [ 14 ] However, in spite of recent advances, multimode luminescent inks with concealing and reliable features against sophisticated counterfeiting are still in demand.…”

Luminescence anti‐counterfeiting: From elementary to advanced

“…The anti‐counterfeiting labels in multilevel luminescence anti‐counterfeiting can change more than two times under the regulation of excitation light, luminescence lifetime, heat stimuli, chemical reagents, mechanical force, and so on. Based on the category of regulation factors, multilevel luminescence anti‐counterfeiting can be divided into five types: (1) regulated by excitation light; [ 64–80 ] (2) co‐regulated by excitation light and luminescence lifetime; [ 81–92 ] (3) co‐regulated by excitation light and heat stimuli; [ 35,63,93–96 ] (4) co‐regulated by excitation light and chemical reagents; [ 16,97–105 ] and (5) co‐regulated by other factors. [ 106–121 ]…”

“…For example, Liu et al. [ 86 ] adopted three kinds of Ce/Eu, Ce/Tb, and Yb/Tm/Ce/Mn co‐doped phosphors to create a 2D covert pattern as anti‐counterfeiting label (Figure 6D). Under the steady irradiation of 254 nm, the whole anti‐counterfeiting label displayed dual‐color fluorescence, while under the steady irradiation of 980 nm laser, only the area “iii” composed of Yb/Tm/Ce/Mn co‐doped phosphors emitted white fluorescence.…”

“…Similarly with luminescence anti‐counterfeiting regulated by excitation light, the luminescence anti‐counterfeiting co‐regulated by excitation light and luminescence lifetime can also be realized by tuning excitation wavelength, [ 81,82,84,85,87–89 ] irradiation time, [ 83 ] and irradiation mode. [ 86 ] But differently, only one kind of excitation light can also realize multilevel luminescence anti‐counterfeiting due to the introduction of temporal dimension. [ 90,91 ]…”