Helically Assembled Rare Earth Fluoride Nanoparticles with Multicolor Circularly Polarized Luminescence for High-Security Anti-Counterfeiting

Abstract

Multicolor circularly polarized luminescence (CPL) materials show considerable potential in the field of advanced anti-counterfeiting. However, it remains challenging to achieve stable inorganic materials with multicolor CPL. In this work, for the first time, chiroptical rare earth (RE) fluoride nanoparticles induced by helical silica are obtained through a facile in situ assembly strategy. The influence of assembly ratio and morphological structure on the luminescence dissymmetry factor (g_lum) has been systematically investigated, leading to an optimized g_lum value of 4.7 × 10⁻³. By adjusting the types and concentrations of RE dopants (Ce³⁺, Tb³⁺, Eu³⁺), the nanocomposites exhibit multicolor CPL and time-resolved photoluminescence characteristics. Remarkably, these nanocomposites retain their CPL activity even after calcination at 400°C. Leveraging the visible multicolor emissions, along with the hidden dynamic and chiroptical signals, the nanocomposites are successfully applied in high-security anti-counterfeiting patterns and multilevel optical encryption codes.