Plasmonic Enhancement of Upconversion Photoluminescence from CaF₂: Er³⁺, Yb³⁺ Nanoparticles on TiN Nanoantennas

Abstract

Photon upconversion is a promising phenomenon that may find application in solar cell, display, and antifake printing. Rare-earth-based upconverters are most widely studied, but they always suffer from their weak and narrow absorption at λ ex = 980 nm. We investigated the plasmon-enhanced upconversion luminescence of CaF 2 : Yb 3+ , Er 3+ nanocrystals on a plasmonic nanoantenna. We selected titanium nitride (TiN) as the constituent of nanoantenna, considering its better thermal stability compared to the conventional plasmonic metals. Well-defined TiN nanoantennas consisting of the square lattice of TiN nanoparticles were fabricated using a nanoimprint technique. By adjusting the height and period of the nanoantenna, we found that the enhancement factor was strongly influenced by the resonance of the nanoantenna at the pumping wavelength. A maximum of 2.98-fold enhancement was obtained for the upconversion photoluminescence intensity. The mechanism of enhancement was examined using three-dimensional simulation with COMSOL Multiphysics in detail, which was highly consistent with the experimental measurements.

Up-conversion Luminescence Enhanced by the Plasmonic Lattice Resonating at the Transparent Window of Water

“…Because the local electromagnetic field of SPR is effective only in a range of a few tens of nanometers around the Al nanocylinder, a thin and uniform UCNP layer (∼60 nm) is a key factor for the high UC enhancement. The enhancement is much less for the thicker UCNP layer, as demonstrated for the Er 3+ –Yb 3+ co-doped system on the plasmonic arrays. , It is noted while the highest enhancement field is accumulated near the nanocylinder like localized SPR, the resonance wavelength is set by the periodicity via diffractive coupling. We also calculate the light energy squared, ∫| E film | 4 d V /∫| E ref film | 4 d V , where | E film | and | E ref film | are the electric fields inside the UCNP layer on the array and the glass substrate, respectively, integrated over the UCNP layer (see Supporting Information Figure S9).…”

“…The enhancement is much less for the thicker UCNP layer, as demonstrated for the Er 3+ −Yb 3+ co-doped system on the plasmonic arrays. 40,57 It is noted while the highest enhancement field is accumulated near the nanocylinder like localized SPR, the resonance wavelength is set by the periodicity via diffractive coupling. We also calculate the light energy squared, ∫ |E film | 4 dV at λ = 808 and 980 nm agree with the experimental results of extinction and UCL enhancement factor qualitatively.…”

Enhancing Up-Conversion Luminescence Using Dielectric Metasurfaces: Role of the Quality Factor of Resonance at a Pumping Wavelength

“…By combining optical emitters with plasmonic metasurfaces, a strong enhancement of photoluminescence (PL) has been demonstrated. − In Figure a, we summarize the examples of PL enhancement, both down- and upconversions, of the explored optical emitters in combination with plasmonic metasurfaces, including organic dyes, fluorescence proteins, quantum dots, and up-converters. In each category, the PL enhancement factor varies depending on the configurations.…”

“…(a) Survey of the plasmonic enhancement of luminescence intensity of the emitters reported since 2005, including organic dye (red), − fluorescence protein (green), − quantum dot (orange), − and up-conversion materials (blue). − (b) Schematic of the sample consisting of an Si metasurface, an UCNP layer, and a polymer layer on the top. (c, d) Top-view SEM images of (c) an as-made Si metasurface and (d) that coated by a monolayer of UCNPs.…”