Rare earth ions doped fluoride Core-Shell structured nanoparticles for dual-wavelength responsive emission color...

Optical information encryption technology based on the emission color from rare earth ions shows great potential with the information security problems increasing. In this work, the up-conversion processes of the core-shell structured Er@Y@Tm phosphors can be precisely controlled by modulating the excitation conditions and temperature. The luminescent centers, Er³⁺ and Tm³⁺, are spatially separated in different layers of the core-shell structure, enabling wavelength responsive pure red and blue emission color under 980 and 1550 nm laser excitation, respectively. For the core-shell structured Er@Y@Ho phosphors, they can also emit green and red emission under 980 and 1550 nm laser excitation, respectively. The emission color can also be tuned through excitation condition, temperature. The superiority of the optical coding and encoding process is demonstrated for information storage. The dual-wavelength responsive pure color up-conversion luminescence can be used as the dynamic information encryption and promote the development of applications in data protection and information security technologies.