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

抄録

Photon upconversion is a promising phenomenon that may find application in solar cell, display, and anti-fake 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 CaF₂: Yb³⁺, Er³⁺ 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.