title: Unclonable Security Codes Designed from Multicolor Luminescent Lanthanide-Doped Y2O3Nanorods for Anticounterfeiting.
abstract: The duplicity of important documents has emerged as a serious problem worldwide. Therefore, many efforts have been devoted to developing easy and fast anticounterfeiting techniques with multicolor emission. Herein, we report the synthesis of multicolor luminescent lanthanide-doped Y2O3nanorods by hydrothermal method and their usability in designing of unclonable security codes for anticounterfeiting applications. The spectroscopic features of nanorods are probed by photoluminescence spectroscopy. The Y2O3:Eu3+, Y2O3:Tb3+, and Y2O3:Ce3+nanorods emit hypersensitive red (at 611 nm), strong green (at 541 nm), and bright blue (at 438 nm) emissions at 254, 305, and 381 nm, respectively. The SEM and TEM/HRTEM results reveal that these nanorods have diameter and length in the range of 80-120 nm and ∼2-5 μm, respectively. The two-dimensional spatially resolved photoluminescence intensity distribution in nanorods is also investigated by using confocal photoluminescence microscopic technique. Further, highly luminescent unclonable security codes are printed by a simple screen printing technique using luminescent ink fabricated from admixing of lanthanide doped multicolor nanorods in PVC medium. The prospective use of these multicolor luminescent nanorods provide a new opportunity for easily printable, highly stable, and unclonable multicolor luminescent security codes for anti-counterfeiting applications.
authors.affiliation: Alternative Energy Materials Section, Advanced Materials and Devices Division, and ‡Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory Campus , Dr K S Krishnan Road, New Delhi 110012, India.
authors.forename: Pawan
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Alternative Energy Materials Section, Advanced Materials and Devices Division, and ‡Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory Campus , Dr K S Krishnan Road, New Delhi 110012, India.
authors.forename: Kanika
authors.initials: K
authors.lastname: Nagpal
authors.affiliation: Alternative Energy Materials Section, Advanced Materials and Devices Division, and ‡Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory Campus , Dr K S Krishnan Road, New Delhi 110012, India.
authors.forename: Bipin Kumar
authors.identifier: http://orcid.org/0000-0002-0176-0007
authors.initials: BK
authors.lastname: Gupta
keywords: counterfeiting and anticounterfeiting; lanthanide; nanorods; photoluminescence