Influence of SiO2 layer thickness on plasmon enhanced upconversion in hybrid Ag/SiO2/NaYF4:Yb, Er, Gd structures

Distance-Dependent Plasmon-Enhanced Fluorescence of Upconversion Nanoparticles using Polyelectrolyte Multilayers as Tunable Spacers

“…That is to say, quantum efficiencies and luminescence intensity of UCNPs can be enhanced or quenched by their surrounding metal nanoparticles40. Plasmon enhancement of the upconversion luminescence could be attributed to three competing effects25314142: (1) an increased excitation rate induced by local field enhancement (LFE) causing enhanced excitation efficiency resulting in fluorescence enhancement; (2) an increased radiative decay rate by surface plasmon-coupled emission (SPCE) from coupling of the upconversion emission with the AuNRs LSPR wavelength, resulting in fluorescence enhancement; (3) the non-radiative energy transfer (NRET) from the UCNPs to the AuNRs resulting in fluorescence quenching. NRET process dominates at the surface and drops off with inverse fourth power of localized electric field41.…”

“…emission luminescence) or the energy transfer process of UCNPs to the metal surface45. The NRET process between UCNPs and metal nanoparticles can enhance non-radiative decay rate and reduce the quantum yield of UCNPs, resulting in the reduced luminescence intensity42. NRET depends mainly on distance between UCNPs and metal nanoparticles and is independent of the excitation wavelength25.…”

“…5a, b. Since the rise and decay time of the fluorescence cannot be fitted as mono-exponential, we determined the rise and decay time by half of its maximal value following literature2442. Compared with UCNPs without plasmon enhancement effect (black curve in Fig.…”

Influence of SiO2 layer on the plasmon quenched upconversion luminescence emission of core-shell NaYF4:Yb,Er@SiO2@Ag nanocomposites

“…Excitation field enhancement effect, emission enhancement effect, and non-radiative decay due to the energy transfer process from excited state of Er 3+ to Ag NPs are three possible competing effects [26] that lead to the fluorescence quenching of the system.…”

“…Some explorations on the luminescence enhancement of metal nanostructures to rare earth doped luminescence materials have been reported, but the results are inconsistent and the mechanism behind the experimental observation is still not well understood [20][21][22][23][24]. For metal enhanced fluorescence emission, spectra characteristics and distance between optical center and metal surface play important roles in the observation of enhancement effect [25][26][27][28][29][30]. Using SiO 2 layer to control the distance between the luminescent material and metal plasmon nanostructure is a popular way to study the influence of the distance dependence, but most of the optical spectral measurements are performed in solution or powder samples, which is not possible to eliminate the influence of aggregation effects and inter-reflection and coupling between sample particles [31][32][33][34].…”