Plasmonic modulated upconversion fluorescence by adjustable distributed gold nanoparticles

In this research, we designed the core/shell/shell model of NaYF₄@SiO₂@Au with adjustable gold nanoparticles (different sizes and distributions) on the surface to enhance the up-conversion luminescence (UCL) intensity. The discrete dipole approximation (DDA) simulation results indicate that the position of the model extinction peak can be changed through changing the number of gold nanoparticles. In theory, if the extinction peak is red-shifted without overlapping with the model emission peak, the luminescence will be effectively enhanced. Then, we synthesized composite with different amounts of gold nanoparticles coated on the surface using layer-by-layer (LBL) electrostatic adsorption methods, and the UCL enhancement effect of difference gold nanoparticles is exactly consistent with the results of DDA simulation. When the extinction peak is best crossed with the excitation (near infrared) region and the extinction peak is not crossed with the emission (visible) region, the enhancement achieves the highest. Therefore, the lanthanide-gold composite with effectively improved UCL intensity could be designed and guided by DDA simulation.