Highly Luminescent Dual Mode Polymeric Nanofiber‐Based Flexible Mat for White Security Paper and Encrypted Nanotaggant Applications

Abstract

Increasing counterfeiting of important data, currency, stamp papers, branded products etc., has become a major security threat which could lead to serious damage to the global economy. Consequences of such damage are compelling for researchers to develop new high-end security features to address full-proof solutions. Herein, we report a dual mode flexible highly luminescent white security paper and nanotaggants composed of nanophosphors incorporated in polymer matrix to form a nanofiber-based mat for anti-counterfeiting applications. The dual mode nanofibers are fabricated by electrospinning technique by admixing the composite of NaYF :Eu @NaYF :Yb , Er nanophosphors in the polyvinyl alcohol solution. This flexible polymer mat derived from nanofibers appears white in daylight, while emitting strong red (NaYF :Eu ) and green (NaYF :Yb , Er ) colors at excitation wavelengths of 254 nm and 980 nm, respectively. These luminescent nanofibers can also be encrypted as a new class of nanotaggants to protect confidential documents. These obtained results suggest that highly luminescent dual mode polymeric nanofiber-based flexible white security paper and nanotaggants could offer next-generation high-end unique security features against counterfeiting.

Dynamic Luminescence Manipulation for Rewritable and Multi-level Security Printing

“…One of the most popular approaches to achieve paper-based security data recording is to use fluorescent security inks where the printed information or patterns are only visible under UV light. [12][13][14][15] To date, the practical applications of security printing in different scenarios have been hampered by several critical challenges. For example, easy operation and low cost are crucial for routine use of security printing.…”

Tunable Photoluminescence of Polyvinyl Alcohol Electrospun Nanofibers by Doping of NaYF4: Eu+3Nanophosphor

“…Herein alcohol to fabricate the nanofibers via electrospinning. These nanofibers display typical Eu +3 emission transition in the 500-725 nm regions [11]. Figure 3(a) shows the photoluminescence spectrum of down shift part of the nanofibers upon the excitation of 239 nm wavelength at room temperature.…”

Implanting bismuth in color-tunable emitting microspheres of (Y, Tb, Eu)BO3 to generate excitation-dependent and greatly enhanced luminescence for anti-counterfeiting applications

“…The distinct emission color from orange to green yellow can be achieved by facile switching the excitation wavelength from 260 nm to 230 nm (Figure 8(C)), which indicate that the phosphor is the potential anti-counterfeiting pigment. Recently, some research groups have made efforts to developing dual emissive pigments based on different excitation wavelengths [3,28,29]. Here, the excitation-dependent emitting (Y, Tb, Eu, Bi)BO 3 spheres with advanced security feature would be a member of the luminescent-pigment family to prevent counterfeiting by generating advanced security feature safety levels.…”