Brilliant emission from Cs3YF6: Tb3+/Eu3+ under deep ultraviolet light excitation for water-sensitive anti-counterfeiting applications

The cesium-based fluoride Cs3YF6 has increasingly attracted curiosity due to its potential in up-conversion luminescence applications, signifying a possible revolutionary change in the next generation of lanthanide-doped luminescent functional materials. However, the nature of the photoluminescence process involving Cs3YF6 has still not been studied in detail. Developing Cs3YF6 luminescence applications is an intricate endeavor. Herein, we present the optimal doping concentration required for Eu3+ and Tb3+ doping in Cs3YF6. Meanwhile, by spectra analyses and theoretical model simulations, we have been able to decipher the intricacies of the energy transfer interaction that transpires between Tb3+ and Eu3+ ions. Furthermore, a water-sensitive fluorescence response system tailored for anti-counterfeiting applications was designed, which relied on the superior luminescence characteristics of Cs3YF6 doped with Tb3+/Eu3+ under excitation at 254 nm, whilst simultaneously exploiting the easily deliquescent nature of Cs3YF6. This work not only enhances the understanding of Cs3YF6 materials in the field of rare-earth luminescence but also introduces a novel anti-counterfeiting strategy, that propels the development of applications for rare-earth-doped fluoride materials.