Enhancing Light and X-Ray Charging in Persistent Luminescence Nanocrystals for Orthogonal Afterglow Anti-Counterfeiting

Persistent luminescence nanoparticles (PLNPs) are an emerging type of optical nanomaterial that possess long-lasting afterglow after the excitation has stopped. Recently, bottom-up synthesis of PLNPs has offered uniform and small nanocrystals that are desirable for various bioapplications. However, the lack of a simple method to enhance the afterglow of these PLNPs is one of the key obstacles hindering their further development and applications. Herein, a simple strategy is demonstrated that can amplify both light and X-ray charged persistent luminescence in monodispersed Zn2GeO4:Mn PLNPs via the non-equivalency substitution of zinc ions with lithium ions in the lattice matrix and concomitant to the electron traps tailoring. It is significant that, in addition to increasing the intensity of the afterglow, this nanoscale atomic level substitution can preserve the desirable uniform size and morphology of the PLNPs. Furthermore, since the two excitations (light and X-ray) are independent of each other, a light/X-ray orthogonally encrypted spatio-temporal dual-dimensional afterglow anti-counterfeiting is demonstrated via these nanoparticles. It is believed that this simple method offers a foundation for new opportunities to unleash the optical performance in PLNPs. This will also pave the way to the development of such PLNPs for numerous photonic and bioapplications, which are limited in existing methods.