Fig. 10
Plasmonic and photonic manipulation of upconversion nanoparticles in enahancing upconverted emission: a Schematic structure of a spin-cast layer of Au or Ag NPs, a thin Al2O3 layer, and a monolayer of UCNs. Integrated area under the peak as a function of the Al2O3 layer thickness normalized to that of the pure UCN sample for (b) Au NPs and (c) Ag NPs. The green solid lines correspond to the 540 nm emission band (510–570 nm) in NaYF4:Yb, Er. The green dashed lines correspond to the 650 nm emission band (640–680 nm) in NaYF4:Yb, Er. The blue solid lines correspond to the 475 nm emission band (461–490 nm) in NaYF4:Yb, Tm. Adapted with permission from Kagan et al.95 (copyright 2012 American Chemical Society). d Schematic illustration of self-assembled photonic crystals with a layer of fluoride UCNs. Upconversion luminescence spectra of NaYF4: Yb/Er (b) and NaYF4:Yb/Tm (e) UCNs on the surfaces of 3D PCs prepared with different polystyrene sphere sizes at 0.4 wt.% concentration. Adapted with permission from Niu et al98(copyright 2014 Royal Society of Chemistry)
