Triple NIR light excited up‐conversion luminescence in lanthanide‐doped BaTiO₃ phosphors for anti‐counterfeiting

Abstract

Rampant counterfeiting is a global problem that poses a serious threat to businesses, consumers, and society, which puts forward urgent requirements for convenient and effective anti-counterfeiting technology with higher confidentiality. 1,2 Traditional anti-counterfeiting technologies, for instance, radio frequency identification (RFID), nuclear track technology, and laser holography, etc., require expensive experimental equipment, complex preparation procedures, and face the risk of information re-writing. 3,4 As an essential candidate, the optical anti-counterfeiting technology based on fluorescent materials has many advantages, such as facile preparation process, convenient visualization, and high confidentiality, and have been widely used in bills, certificates, currency, and various kinds of products. 5 Usually, the fluorescent patterns cannot be identified by naked eyes in natural light, and become visible by ultraviolet (UV) or infrared light stimuli, so it has good confidentiality. [6][7][8] The representative UV-stimulated fluorescent materials such as organic fluorescent dyes, quantum dots (QDs), and metal-organic frameworks (MOFs) suffer from the inferior stability, background noise, and light bleaching. [9][10][11] In comparison, near-infrared (NIR) light pumped rare-earth-doped UC materials are ideal candidate for optical anti-counterfeiting labels because of the superior physical and chemical stability, big anti-Stokes shift, long luminescence life, light resistance to bleaching, and so

Recent progress on lanthanide-based long persistent phosphors: an overview

“…Often, the use of some laser excitation reveals different patterns on the currency. Some of the phosphors that can be utilised are BaTiO 3 :Er 3+ ,Er 3+ –Ho 3+ ,Yb 3+ –Tm 3+ ; 12 and SrBi 4 Ti 4 O 15 :Er 3+ (SBTO:Er 3+ ). 67 a Among the available techniques, the luminescent printing practice has gained much attention due to its distinctions of easy and scalable production, simple operation, and most importantly tuneable and customizable optical performance.…”

“…Long persistent phosphors have widely found applications in signalling, including optical displays, sensing, military applications, emergency signs, and anti-counterfeiting. 5,[10][11][12][13] However, their application has been extended to the fields of optical storage 14 and bioimaging due to their peculiar energy ranges, which are in the biologically transparent window, i.e., the infrared region. 1 Previously, sulphur-based hosts were widely used, but recently their interest has depleted due to their shortcomings, mainly chemical instability.…”

ZGSO Spinel Nanoparticles with Dual Emission of NIR Persistent Luminescence for Anti-Counterfeiting Applications

“…Anti-counterfeiting also employs photoluminescent materials due to their high throughput, low cost, flexibility, and stability [ 4 , 5 ]. Current optical-based anti-counterfeiting technologies are mainly based on down-conversion or up-conversion luminescence under excitation [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. However, real-time fluorescence of lanthanides for anti-counterfeiting purposes is susceptible to producing interference with the background and excitation light [ 13 ].…”