Enhanced red upconversion luminescence by codoping Ce³⁺ in β-NaY(Gd_0.4)F₄:Yb³⁺/Ho³⁺ nanocrystals

Abstract

The UC fluorescence emission and tuning from Ce3+ codoped β-NaY(Gd0.4)F4:Yb3+/Ho3+ nanocrystals.

NaGd(MoO4)2 nanocrystals with diverse morphologies: controlled synthesis, growth mechanism, photoluminescence and thermometric properties

“…Small peaks at about 2927 and 2856 cm −1 are attributed to the stretching vibration of –CH 2 in skeletal chain of oleic acid. The peaks at about 1635 and 1460 cm −1 are ascribed to the vibrations of the C = O groups of oleic acid39. The strong absorption bands at 796 and 704 cm −1 are assigned to the F 2 (ν 3 ) antisymmetric stretch and the peak at 434 cm −1 is ascribed to F 2 (ν 4 ) bending mode vibrations related to the O–Mo–O stretching vibrations in the MoO 4 tetrahedron40.…”

Effects of Ce3+ Doping in Green-Red Emitting Upconversion Nanoparticles

“…To explain such anomalous phenomena, the population processes of each emitting level in emitter ions are studied. The energy transfer upconversion processes in Yb 3+ ‐Er 3+ ‐Ce 3+ has been well studied in the past years . In Ho 3+ ions, the green emission band is originated from 5 F 4 / 5 S 2 level, which is populated by the following processes: …”

“…NR refers to the non‐radiative relaxation process from one energy level to the lower‐lying level (Figure a). It should be noted that in both two routes to populate the 5 F 5 level there are NR processes involved, which are believed can be accelerated by the energy transfer interactions between Ce 3+ and Ho 3+ ions (as shown in Figure b), since Ce 3+ ion has an exclusive energy gap of ∼3000 cm −1 , which matches the energy gap in the aforementioned NR processes of Ho 3+ ions, Therefore, the green‐to‐red upconversion intensity ratio of Yb 3+ ‐Ho 3+ ‐Ce 3+ system is gradually decreased with increase the Ce 3+ concentration. On the other hand, the gradually shortened luminescent decay lifetimes of Ho 3+ emission by adding more Ce 3+ dopants (Figure e and Figure S5b) demonstrate that the ET between Ce 3+ ions and Ho 3+ is occurring.…”

Influence of SiO2 layer on the plasmon quenched upconversion luminescence emission of core-shell NaYF4:Yb,Er@SiO2@Ag nanocomposites

“…Up to now, many strategies have been proposed for improving the efficiency, which include the chemical modification, crystal structure and local field adjustment, introduction of codopant sensitizers and hybrid configuration, etc [10][11][12][13][14][15]. With development of plasmonic and surface enhanced spectroscopy, noble metal nanoparticles(NPs) has been considered as a new way to enhance the UC luminescence efficiency [16][17][18][19][20][21][22][23][24].…”