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 NaYF₄:Eu³⁺@NaYF₄:Yb³⁺, Er³⁺ nanophosphors in the polyvinyl alcohol solution. This flexible polymer mat derived from nanofibers appears white in daylight, while emitting strong red (NaYF₄:Eu³⁺) and green (NaYF₄:Yb³⁺, Er³⁺) 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. [ABSTRACT FROM AUTHOR]