Binary temporal upconversion codes of Mn2+-activated nanoparticles for multilevel anti-counterfeiting

Xiaowang Liu,Xiaogang Liu,Xiyan Li,Zhigao Yi,Yu Wang,Dianyuan Fan,Renren Deng,Shuyan Song,Hongjie Zhang,Ling Huang,Liangliang Liang,Xiaoji Xie,Daniel T B Loong,Angelo H All

doi:10.1038/s41467-017-00916-7

Abstract

Optical characteristics of luminescent materials, such as emission profile and lifetime, play an important role in their applications in optical data storage, document security, diagnostics, and therapeutics. Lanthanide-doped upconversion nanoparticles are particularly suitable for such applications due to their inherent optical properties, including large anti-Stokes shift, distinguishable spectroscopic fingerprint, and long luminescence lifetime. However, conventional upconversion nanoparticles have a limited capacity for information storage or complexity to prevent counterfeiting. Here, we demonstrate that integration of long-lived Mn2+ upconversion emission and relatively short-lived lanthanide upconversion emission in a particulate platform allows the generation of binary temporal codes for efficient data encoding. Precise control of the particle’s structure allows the excitation feasible both under 980 and 808 nm irradiation. We find that the as-prepared Mn2+-doped nanoparticles are especially useful for multilevel anti-counterfeiting with high-throughput rate of authentication and without the need for complex time-gated decoding instrumentation.

Highlights

Optical characteristics of luminescent materials, such as emission profile and lifetime, play an important role in their applications in optical data storage, document security, diagnostics, and therapeutics
One promising strategy that simplifies the coding and decoding procedure is the integration of long-lived emission (>15 ms) with conventional upconversion emission for distinct binary temporal scales that can be visualized on excitation at a single wavelength
By making use of energy migrators to link the two emitting centers, we report the access to binary temporal upconversion codes benefiting from the large lifetime difference in their emissions

Summary

Introduction

Optical characteristics of luminescent materials, such as emission profile and lifetime, play an important role in their applications in optical data storage, document security, diagnostics, and therapeutics. Time-domain codes of lanthanide-doped nanoparticles have proven effective in adding flexibility in high-density data storage and another dimension of complexity to combat counterfeiting[23,24,25]. Optical nanoparticles that simultaneously display a long-lived emission and a relatively short-lived emission are generally difficult to prepare by direct coating of conventional afterglow materials such as MAl2O4:Eu2+/Dy3+ (M=Ca or Sr) onto lanthanidedoped nanocrystals, typically composed of NaGd(or Y)F4:Yb/Er (or Tm). This difficulty is largely due to the challenge of mitigating the large lattice mismatch between the two materials. Optical incompatibility between the pair in some cases can even lead to deleterious cross-relaxation, resulting in rapid quenching of excitation energies[27,28,29]

Methods

Results

Conclusion