Enhanced Photoluminescence in CeF3–YF3–TbF3 Colloids via Gold Nanoparticles

The enhancement of photoluminescence in colloids represents a vital field of photonics, advancing real-world applications in lighting, sensing, and beyond. A colloidal ternary system CeF3–YF3–TbF3 emits green photoluminescence (PL) under ultraviolet pulsed pumping. In this paper, we demonstrate that introducing gold nanoparticles (Au NPs) to the colloidal solution enhances PL via indirect optical transitions. Contrary to common expectations, larger Au NPs with a diameter of 95 nm exhibit a 2.5-fold enhancement in PL, whereas smaller Au NPs enabling a high-Q plasmon resonance, shows significantly less enhancement. Herein, we represent a novel mechanism for PL enhancement enabled by green PL acting as the pump source.