Steady State Luminescence Enhancement in Plasmon Coupled Core/Shell Upconversion Nanoparticles

Abstract

Plasmon enhanced upconversion luminescence has been deeply investigated and finds extensive applications from fluorescent sensors to cancer therapy. Here, the steady state luminescence enhancement is shown in plasmonic substrate coupled upconversion nanoparticles (UCNPs). The plasmonic Au‐nanohole‐nanoplate bilayer arrays (PABAs) are designed for generating full‐covered local field which couple both the excitation and the emission field of core/shell UCNPs. By tuning the coupling distance through a 3 nm thick inert shielding shell on upconversion nanoparticles, the plasmon enhanced upconversion luminescence enhancement is found independent on excitation power. This effect will greatly facilitate the applications of plasmon enhanced upconversion nanoparticles as biosensors even under extremely weak excitation. E.g., PABA‐supported core/inert–shell UCNPs are employed as a fluorescent sensor for detecting acetic acid gas, and a linear relationship between upconversion luminescent intensity and acetic acid concentration can be obtained as expected, accompanied by a detection limit of 81 nmol mL−1, which is one order of magnitude lower than the best level ever reported.

Tunable Fano Resonance and Enhanced Sensing in a Simple Au/TiO2 Hybrid Metasurface

“…Surface plasmons (SPs) are collective oscillations of excited electrons at the interface between the metal and dielectric, which can effectively confine and enhance the electric filed [1][2][3][4]. Thus, SPs have important applications in the field of optical sensings, lasers, photovoltaics, and so on [5][6][7][8][9]. Local surface plasmon resonances (LSPRs) is one kind of SPs, which are strongly confined at the surface of metal nanostructures with non-ignorable losses [10][11][12][13][14].…”

Up-to-Five-Photon Upconversion from Near-Infrared to Ultraviolet Luminescence Coupled to Aluminum Plasmonic Lattices

“…We prepared hexagonal-phase NaErF 4 @NaYF 4 core–inert shell UCNPs, comprising ∼35 nm (in diameter) of NaErF 4 as the core and ∼7 nm of non-doped NaYF 4 as the shell, by a solvothermal method (Figure b). We adopted the core–inert shell UCNP because it suppresses the inherent surface defects and energy dissipation to the metal and gives a brighter UCL than core-only and core-active shell NPs. − We synthesized NaGd 1- x Er x F 4 @NaYF 4 NPs in the range of 0.05 < x < 1 and found the UCL is brightest when x = 1. The size of UCNPs (50 nm in diameter) is tuned to make a conformal and densely packed monolayer on the plasmonic lattice.…”

Surface plasmon resonance of Au/Ag metals for the photoluminescence enhancement of lanthanide ion Ln3+ doped upconversion nanoparticles in bioimaging

“…7a, Zhan coupled plasmonic Au-nanohole-nanoplate bilayer arrays (PABAs) with core-shell nanoparticles. 94 The results demonstrated a 6-fold increase in the green emission of core-shell UCNPs after coupling, which was proportional to the irradiation intensity from 12.5 to 50 mW mm À2 , arising from a stimulated local electric field of PABAs and coherent interference of the SPR effect with the emission band. Similarly, but further, Das and his group synthesized dispersible metal-insulator-metal (MIM) structures (inset in Fig.…”

“…7 (a) The fabrication process of the AAO@Au@CS-UCNPs. 94 (b) Green emission spectra of the reference sample and the (MIM) structure of varying diameters under 980 nm excitation. The reference sample emission is magnified by 10 to show the relevant features.…”