Dual-mode excitable Vis/NIR-II luminescence of lanthanide-doped core@multishell nanostructures for anti-counterfeiting and imaging of latent fingerprints

The development of luminescent materials that can simultaneously realize multiple emissions can help improve the reliability of anti-counterfeiting and the security of encrypted information. Lanthanide-doped nanomaterials are very suitable for advanced anti-counterfeiting applications because of their abundant 4 f energy levels and near-infrared (NIR) laser excitability. Herein, we design lanthanide-doped core@multishell nanoparticles NaYF4:Yb,Er/Ho/Tm@NaYF4@NaYF4:Nd@NaYF4, which can realize upconversion luminescence of Er/Ho/Tm under 980 nm excitation, as well as non-overlapping NIR-II luminescence under 980 nm or 808 nm excitation. By precisely controlling the distribution of lanthanide ions in the core-shell layer, the luminescence interference of nanomaterials under different wavelength excitation can be avoided. Experiments show that multi-color security and information encryption under NIR laser excitation can be achieved using aqueous inks containing the designed multilayered core-shell nanostructures, which are covert and difficult to forge. And the multilayer core-shell nanopowder can be used for efficient identification of latent fingerprints on complex surfaces.