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

Abstract

AbstractPlasmon 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.