Qibin Yang

Tri-color upconversion luminescence of Rare earth doped BaTiO 3 nanocrystals and lowered color separation

Upconversion tri-color luminescence of Er(3+)/Tm(3+)/Yb(3+) doped BaTiO3 nanocrystals is observed under the excitation of a 980 nm laser diode. Especially, Er(3+) emission has a considerable contribution to the blue portion of the UC spectra, different from the ever-reported results, in which blue emission originates only from Tm(3+). This realization is beneficial to lower the color separation between blue and green (or red) emissions, in fluorescent labeling. The analysis of excitation power dependence and decay time revealed that blue emission of Er(3+) ion is induced by a dual energy transfer upconversion, while Tm(3+) plays a role of both emitter and activator.

White upconversion of rare-earth doped ZnO nanocrystals and its dependence on size of crystal particles and content of Yb3+ and Tm3+

Rare earth (RE) doped ZnO nanocrystals were synthesized by chemical combustion method. Bright white upconversion (UC) luminescence with the CIE coordinates close to (0.33, 0.33) was obtained in Er+Tm+Yb tridoped ZnO nanocrystals under the excitation of a cost-effective 980 nm single-wavelength laser diode. The overall and relative UC luminescence intensities of RE doped ZnO nanocrystals were found to be depended highly on the diameter of crystal particles and the concentration of Yb3+ and Tm3+, for which the involved mechanisms were demonstrated. The investigation based on UC spectra, simplified energy level diagram, and excitation power dependence indicated that the remarkable enhancement of the green emission of the RE tridoped sample was due to a dual sensitization of Er3+ by Yb3+ and Tm3+ ions. The RE tridoped ZnO nanocrystals with the CIE coordinates close to (0.33, 0.33) are potentially suitable for the widely realistic application as the multicolor fluorescent labels, due to a fact that they could ...

Single-narrow-band red upconversion fluorescence of ZnO nanocrystals codoped with Er and Yb and its achieving mechanism

ZnO nanocrystals doped with Er3+ and Yb3+ ions were synthesized by the chemical-combustion process. The single-narrow-band red fluorescence (centered at 662 nm) in ZnO:Er, Yb was observed under 115 mW excitation of a 980 nm laser diode. The full width at half maximum of the red emission band is equal to 30 nm, which is the narrowest emission band ever reported in Er3+ doped systems. This narrower emission band in ZnO:Er, Yb nanocrystal is beneficial for improving the precision and sensitivity of the indicators in fluorescent label detection. The mechanisms resulting in the single-narrow emission band were analyzed by combining X-ray diffraction, Raman spectra, fluorescence spectra, and a simple model.ZnO nanocrystals doped with Er3+ and Yb3+ ions were synthesized by the chemical-combustion process. The single-narrow-band red fluorescence (centered at 662 nm) in ZnO:Er, Yb was observed under 115 mW excitation of a 980 nm laser diode. The full width at half maximum of the red emission band is equal to 30 nm, which is the narrowest emission band ever reported in Er3+ doped systems. This narrower emission band in ZnO:Er, Yb nanocrystal is beneficial for improving the precision and sensitivity of the indicators in fluorescent label detection. The mechanisms resulting in the single-narrow emission band were analyzed by combining X-ray diffraction, Raman spectra, fluorescence spectra, and a simple model.