Enhancement of red upconversion emission of cubic phase NaLuF4: Yb3+/Ho3+/Ce3+ nanocrystals

• The upconversion emission of Ho3+ ions was tuned from green to red.
• The upconversion mechanism of Ho3+ ions was discussed based on emission spectrum.
• The conversion efficiency between Ho3+ and Ce3+ were studied and calculated.

The red upconversion emission of lanthanide-doped fluoride nanocrystals have great potential applications in color display and anticounterfeiting applications, especially for biological imaging and biomedical. In this work, a significant enhancement of red upconversion emission of Ho3+ ions was successfully obtained in the cubic phase NaLuF4 nanocrystals through codoping Ce3+ ions under NIR 980 nm excitation. The ratio of red-to-green emission of Ho3+ ions was enhanced about 10-fold, which is due to two efficient cross relaxation processes derived from Ho3+ and Ce3+ ions promoted the red emission and quenched the green emission. The upconversion emission and luminescent colors of NaLuF4: Yb3+/Ho3+ nanocrystals were carefully investigated by a confocal microscopy setup. The possible upconversion emission mechanism and conversion efficiency of cross relaxation between Ho3+ and Ce3+ ions were discussed in detail. The current study suggests that strong red emission of NaLuF4: Yb3+/Ho3+/Ce3+ nanomaterials can be used for color display and anticounterfeiting techniques.

Figure optionsDownload as PowerPoint slideThe upconversion emission of Ho3+ was tuned from green to red because of two efficient cross relaxation between Ho3+ with Ce3+.