Enhancing the color purity of the green upconversion emission from Er3+/Yb3+-doped GdVO4 nanocrystals via tuning of the sensitizer concentration

Abstract

Here we report on the enhancement of the intensity of the green/red emission ratio in Er³⁺/Yb³⁺-doped GdVO₄ nanocrystals obtained via the upconversion process. The nanocrystals were synthesized using a sol–gel process followed by a solid-state reaction. A series of samples bearing different sensitizer ion (Yb³⁺) concentrations were studied and characterized. Tripositive erbium (Er³⁺)-doped GdVO₄ shows two strong emissions in the green region near 525 and 550 nm while a relatively weak red emission is centred at 660 nm. A 5-fold increase in the intensity of the green/red emission ratio is observed for the Er³⁺/Yb³⁺-doped GdVO₄ sample co-doped with 20 mol% Yb³⁺ concentration in comparison to a similar sample without any Yb³⁺. This suggests a corresponding increase in the color purity of the green emission and as a consequence, this material would be an interesting candidate as a phosphor for display and LED applications.