Excitation energy mediated cross-relaxation for tunable upconversion luminescence from a single lanthanide ion

Abstract

Precise control of energy migration between sensitizer ions and activator ions in lanthanide-doped upconversion nanoparticles (UCNPs) nowadays has been extensively investigated to achieve efficient photon upconversion. However, these UCNPs generally emit blue, green or red light only under fixed excitation conditions. In this work, regulation of the photon transition process between different energy levels of a single activator ion to obtain tunable upconversion fluorescence under different excitation conditions is achieved by introducing a modulator ion. The cross-relaxation process between modulator ion and activator ion can be controlled to generate tunable luminescence from the same lanthanide activator ion under excitation at different wavelengths or with different laser power density and pulse frequency. This strategy has been tested and proven effective in two different nanocrystal systems and its usefulness has been demonstrated for high-level optical encryption.

Recent advances in polyoxometalate-based lanthanide–oxo clusters

“…This special electronic configuration of lanthanides ions giving rise to a variety of new lanthanide materials with unique properties in light, magnetism, catalysis, and electrochemistry, etc. [1][2][3][4][5][6]. Lanthanide-oxygen clusters (LnOCs) are polynuclear metal complexes bonded through Ln-O-Ln groups in the structure.…”

Hydrophobicity Regulation of Energy Acceptors Confined in Mesoporous Silica Enabled Reversible Activation of Optogenetics for Closed-Loop Glycemic Control

“…11 Despite these early advances, an important limitation of many current approaches is that invasive fiber or implanted micro light-emitting diodes are needed to activate photosensitive proteins for regulating activity of cells in deep tissue regions, which inevitably causes tissue damage, inflammation, infection, and limitations of animal behaviors. 12 Recently, lots of luminescent nanomaterials, such as lanthanide-doped upconversion nanoparticles (UCNPs), 13,14 scintillants, 15 quaternary oxysulfides, 16 graphene, 17 and liposomes, 18 have been broadly used as light transducers to activate photosensitive proteins through near-infrared light, Xray, or magnetic forces with deeper tissue penetration to realize noninvasive and tether-free optogenetic applications. 19,20 However, a major challenge remains that they provide little or even no control over the strength, timing, or cellular context of the therapeutic effect through a closed-loop regulation.…”

Defect-assisted dynamic multicolor modulation in KLu3F10:Tb crystals for anti-counterfeiting

“…[1][2][3][4][5][6] Several nanoparticles with designed core/shell structure have been used to realize excitation-dependent multicolor upconversion emissions. [7][8][9][10][11] For example, the emission color of NaYF 4 :Yb/Ho/Ce@NaYF 4 : Yb@NaNdF 4 :Yb nanoparticles was changed from green to red upon switching the excitation wavelength from 808 nm to 980 nm; 12 the observed emission color of NaGdF 4 :Yb/ Tm@NaGdF 4 @NaYbF 4 :Nd@Na(Yb,Gd)F 4 :Ho@NaGdF 4 nanoparticles was changed from green to blue when the excitation wavelength was tuned from 808 nm to 976 nm. 13 To avoid the use of expensive and dangerous lasers, several UV-excited downshifting materials were employed to control the emission colors.…”