Upconversion Luminescence Quenching And Application Of Single Au Nanoparticles Decorated NaYF₄:Yb³⁺,Er³⁺Hexagonal Disk

Because of the powerful means to improve the fluorescence radiation efficiency,surface plasmon-induced fluorescence enhancement of rare earth up-conversion luminescent materials have received much interest and been widely investigated in recent years.In recent years,surface plasmon resonance induced up-conversion luminescence enhancement has been studied in experimentally,but the exploration of its specific mechanism has been rarely reported.Various fluorescence quenching channels have been reported as inducing fluorescence enhancement in the hybrid system composed of the surface plasmon and rare earth doped up-conversion material.It is very significance to study the quenching mechanism and provide a theoretical reference for the enhancement of the fluorescence radiation efficiency of such hybrid systems.Because of attractive low phonon energy and low lattice structure symmetry,the hexagonal phase NaYF4 with easy f-f degeneration of the forbidden transition of luminescent have attracted significant attention and been studied for long time.In the present work,different amounts of Au nanoparticles modified hexagonal phase NaYF4:Yb3+,Er3+ hexagonal synthesized by hydrothermal method have been investigated using reliable experimental method.It is found that the average up-conversion quenching factor of the green and red up-converted fluorescence emission bands of a single hexagonal disc loaded with different amounts of Au nanoparticles compared with a single NaYF4:Yb3+,Er3+hexagonal disc.In the present work,the distribution characteristics,laws of the fluorescence radiation in the system and the quenching phenomenon induced by gold nanoparticles have been investigated based on various characterizations and analysis of the fluorescence frequency and time domain spectra using the quasi-geometric construction of the model as well as the finite element method.It is found that the presence of the high-mode Purcell factor induces a significant non-radiative energy transfer from the luminescent ions in the matrix lattice to the Au nanoparticles,contributing to a significant quenching of the up-converted fluorescence and the localized field induced by the plasmon on the Au surface has little effect on the fluorescence quenching.The suggested quenching factor is in good agreement with the experimental results,and the rationality of this strategy for the luminescence quenching mechanism is confirmed.The study will give a powerful guidance as to the investigation of an up-conversion system with higher fluorescence radiation efficiency.With the help of the current result,the application potential and the general plan of the hybrid system in enhancing the photosynthesis of crops in greenhouse have been presented.