Phonon-assisted energy back transfer-induced multicolor upconversion emission of Gd₂O₃:Yb³⁺/Er³⁺ nanoparticles under near-infrared excitation

Abstract

Manipulation of upconversion (UC) emission is of particular importance for multiplexed bioimaging. Here, we precisely manipulate the UC color output by utilizing the phonon-assisted energy back transfer (EBT) process in ultra-small (sub-10 nm) Gd2O3:Yb(3+)/Er(3+) UC nanoparticles (UCNPs). We synthesized the Gd2O3:Yb(3+)/Er(3+) UCNPs by adopting the laser ablation in liquid (LAL) technique. The synthesized Gd2O3:Yb(3+)/Er(3+) UCNPs are small spherical and monoclinic structures. Continuous color-tunable (from green to red) UC fluorescence emission is achieved by increasing the concentration of Yb(3+) ions from 0 to 15 mol%. A phonon-assisted energy back transfer (EBT) process from Er(3+) ((4)S3/2 → (4)I13/2) to nearby Yb(3+) ((2)F7/2 → (2)F5/2), which can significantly enhance red emission at 672 nm and decrease green emission, is responsible for the color-tunable UC emission by increasing the Yb(3+) concentration in Gd2O3:Yb(3+)/Er(3+) UC nanoparticles.

Tailoring solar energy spectrum for efficient organic/inorganic hybrid solar cells by up-conversion luminescence nanophosphors

“…2b, there are three obvious peaks located at 142.91, 148.42 eV and 170.73 eV, corresponding to the spin-orbit doublet Gd 4d5/2, Gd 4d3/2 and Er 4d, respectively. The peak positions are in good agreement with the characteristics for the oxidation state of Gd 3+ and Er 3+ [28,29]. The above XRD and XPS results demonstrate that Er 3+ ions were doped into the Gd 2 (MoO 4 ) 3 host matrix successfully.…”

Phase evolution, structure, and up‐/down‐conversion luminescence of Li6CaLa2Nb2O12:Yb3+/RE3+ phosphors (RE = Ho, Er, Tm)

“…It is also seen from Figure A that the green band well splits into four sharp peaks centered at ~ 524, 540, 551 and 568 nm, respectively, which indicates that the 2 H 11/2 and 4 S 3/2 energy levels of Er 3+ are subjected to substantial splitting by the dodecahedral coordination environment in Li 6 CaLa 2 Nb 2 O 12 . Such a phenomenon was found for Gd 2 O 3 :Yb/Er, Y 2 O 3 :Yb/Er, LiYF 4 :Yb/Er, and NaLu(WO 4 ) 2 :Yb/Er, but hardly for YbPO 4 :Er, YPO 4 :Yb/Er and Sr 3 Y(PO 4 ) 3 :Yb/Er orthophosphates, La 2 O 2 S:Yb/Er oxysulfide, and La 2 O 2 SO 4 :Yb/Er oxysulfate . In addition, the broad and diffuse red luminescence extending from ~ 640 to 700 nm (Figure A) was similarly observed for Ba 5 Gd 8 Zn 4 O 21 :Yb/Er UC phosphor in the ~ 640‐680 nm spectral region, which was ascribed to widening of the 4 F 9/2 energy level by electronic interactions and spin‐orbit coupling .…”

“…Fluoride and oxide are the most frequently used hosts in the UC field, since the former has the advantages of high luminescence efficiency, multicolor tunability and high sensitivity in temperature sensing, while the latter has the superiorities of desirable chemical stability and high feasibility of commercial production via simple synthesis. Among oxides, the garnet‐type compounds have received enormous interest due to their favorable chemical, physical, structural, and optical properties.…”

Magnetic and fluorescent Gd₂O₃:Yb³⁺/Ln³⁺ nanoparticles for simultaneous upconversion luminescence/MR dual modal imaging and NIR-induced photodynamic therapy

“…32 Our recent work has focused on the synthesis and development of ultra-small (sub-10 nm) lanthanide-doped Gd 2 O 3 nanoparticles for MR/fluorescence dual-modal imaging. [33][34][35][36] However, to the best of our knowledge, the ability of lanthanide-doped Gd 2 O 3 UCNs for theranostics application, which combines the diagnosis and treatment of cancer, has not previously been reported. In this contribution, the aim was to synthesis magnetic and fluorescent lanthanide-doped Gd 2 O 3 UCNs and simultaneously achieve MR/UCL dual-modal imaging and PDT.…”