Reversible Upconversion Luminescence Modification Based on Photochromism in BaMgSiO₄:Yb³⁺,Tb³⁺ Ceramics for Anti‐Counterfeiting Applications

Abstract

Reversible upconversion luminescence modification based on photochromism has received considerable interest due to its potential applications in optical storage and high‐sensitivity optical switches. However, stimulation‐induced bleaching by an external thermal field is generally used for photochromism‐induced reversible upconversion luminescence modification, which limits its practical application. In this work, a gray BaMgSiO4:Yb3+,Tb3+ ceramic is prepared, exhibiting the photochromism from gray to pink color when stimulated by 254 nm light. Interestingly, the pink BaMgSiO4:Yb3+,Tb3+ ceramic can be bleached by either a 473 nm laser or thermal stimulation. The reversible change between gray and pink color exhibits excellent reproducibility over several cycles by alternating between 254 and 473 nm (or thermal) light stimulation. The influence of the reversible photochromism of the BaMgSiO4:Yb3+,Tb3+ ceramic on its upconversion luminescence is investigated. Reversible modification of the upconversion luminescence is demonstrated by alternating between 254 and 473 nm (or thermal) light stimulation. For reversible modulation of the upconversion luminescence, excellent reproducibility is realized after several cycles. As an example, the application of the BaMgSiO4:Yb3+,Tb3+ photochromic ceramic as an anti‐counterfeiting agent is described.

Multimodal Luminescent Yb3+/Er3+/Bi3+‐Doped Perovskite Single Crystals for X‐ray Detection and Anti‐Counterfeiting

“…Presently, the realization of concurrent upconversion (UC) and DS have been successfully utilized in anti‐counterfeiting based on the lanthanide‐based dopants. [ 6–9 ] The Eu‐doped down‐shift luminescent materials have been applied in the Euro banknotes, which enables the visible photoluminescence (PL) based on UV lamp excitation. Meanwhile, the Bank of China also introduced the Yb/Er‐doped UC phosphors in the banknotes as the counterfeiting technique, which emits the yellow UC luminescence by the irradiation of 980 nm laser.…”

Optical temperature sensor based on upconversion luminescence of Er3+ doped GdTaO4 phosphors

“…Upconversion (UC) luminescence refers to the conversion of electromagnetic waves from long to short wavelengths through multi‐photon processes where the absorption of infrared (IR) photons leads to visible emission, which has attracted a lot of attention on the bioimaging, 3‐D color display, printing ink, state‐of‐the‐art lighting, solar cell, fingerprint acquisition, anti‐counterfeiting, and so on 1‐7 . Particularly, based on the measurement of temperature‐dependent UC luminescence intensity of two thermally coupled energy levels of trivalent rare earth (RE 3+ ) ions, the non‐contact optical temperature sensor by using the fluorescence intensity ratio (FIR) technique still keeps a research hotspot in recent years owing to its advantages of fast response, high sensitivity and resolution 8‐13 . Under consideration of UC luminescence and temperature sensing properties, the Er 3+ ion with a pair of thermally coupled energy levels ( 2 H 11/2 and 4 S 3/2 ) is often regarded as the one of the most important activator ions to obtain strong UC luminescence in visible range under excitation of IR radiation because of its abundant metastable energy levels and high luminescent quenching concentration; meanwhile, it is also desirable in developing optical temperature sensors 14‐17 …”

Reversible multiplexing for optical information recording, erasing, and reading-out in photochromic BaMgSiO4:Bi3+ luminescence ceramics

“…These results indicate that the BaMgSiO 4 :Bi 3+ ceramics may be available as an optical storage media. Previous investigations demonstrated that the optical storage dimension and density can be expanded by multiplexing the luminescence intensity through the adjustment of the excitation light power [7,8,58]. Fig.…”