Highly luminescent dual mode rare-earth nanorod assisted multi-stage excitable security ink for anti-counterfeiting applications

Abstract

In this paper, the synthesis of multi-stage excitable (379 nm, 980 nm and 1550 nm), highly luminescent3+ nanorods by a hydrothermal method which can emit both hypersensitive green (562 nm) and strong red (660 nm) in a single host lattice and which can be used for a transparent security ink application is reported. Furthermore, these luminescent nanorods also exhibit both down-shift (1127 nm) as well as upconversion (562 nm) features at a single excitation near infrared wavelength of 980 nm. The characterization of these luminescent nanorods was explored by studying their structure/microstructure, using photoluminescence and time-resolved spectroscopic techniques. Furthermore, these luminescent nanorods exhibited the tuning of emission colours from red to green by controlling the sintering temperature. It was demonstrated that these novel luminescent nanorods offer new opportunities for making high-end, multi-stage excitable transparent security ink. The state-of-art production process of ink is easy and it is most suitable for bulk production at an economical cost. Thus, the security inks could be used globally in applications for protection against counterfeiting.

Bifunctional Luminomagnetic Rare-Earth Nanorods for High-Contrast Bioimaging Nanoprobes

“…The FTIR spectrum of heated nanorods at 800 °C shows no peak around 3400 cm −1 due to absence of OH group as shown in Fig. S2b (see Supplementary Information), which suggests that the hydroxide formed (Gd(OH) 3 :Eu 3+ ) at 180 °C during hydrothermal process is completely converted into oxide form (Gd 2 O 3 :Eu 3+ ) on calcination temperature at 800 °C30. The important absorption peak at 748 cm − 1 is assigned to vibration of Gd–O, suggesting that the Gd(OH) 3 :Eu 3+ nanophosphors has converted to Gd 2 O 3 :Eu 3+ nanorods after calcinating as shown in Fig.…”

Future prospects of luminescent nanomaterial based security inks: from synthesis to anti-counterfeiting applications

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Counterfeiting of valuable documents, currency and branded products is a challenging problem that has serious economic, security and health ramifications for governments, businesses and consumers all over the world. 12 The efforts have yielded positive results but still 70 there is further demand to develop improved anti-counterfeiting

Counterfeiting is an increasingly high-tech crime and it calls for high-tech solutions to prevent and deter the acts of counterfeiting.…”

Large-scale synthesis and screen printing of upconversion hexagonal-phase NaYF4:Yb3+,Tm3+/Er3+/Eu3+ plates for security applications

“…2,15 Therefore, several of traditional luminescent materials were developed as a shield against counterfeiting during the past decades, such as photochromic compounds 16 and semiconductor quantum dots (QDs), 17 which are often based on downconversion mechanism (the shorter-wavelength light is used to excite longer-wavelength visible emission). 2,15 Therefore, several of traditional luminescent materials were developed as a shield against counterfeiting during the past decades, such as photochromic compounds 16 and semiconductor quantum dots (QDs), 17 which are often based on downconversion mechanism (the shorter-wavelength light is used to excite longer-wavelength visible emission).…”

“…2,15 Therefore, several of traditional luminescent materials were developed as a shield against counterfeiting during the past decades, such as photochromic compounds 16 and semiconductor quantum dots (QDs), 17 which are often based on downconversion mechanism (the shorter-wavelength light is used to excite longer-wavelength visible emission). 2,[21][22][23][24] However, there are some disadvantages of downconversion luminescent materials to hinder their further applications, such as high toxicity, duplication easily and broad emission bands. 2,[21][22][23][24] However, there are some disadvantages of downconversion luminescent materials to hinder their further applications, such as high toxicity, duplication easily and broad emission bands.…”