Enhancement of upconversion luminescence of Y2O3:Er3+ nanocrystals by codoping Li+–Zn2+

The upconversion (UC) luminescence in sol–gel synthesized Li+, Zn2+, or Li+–Zn2+ codoped Y2O3:Er3+ nanocrystals were investigated under the excitation of a 970 nm diode laser. Compared to undoped Y2O3:Er3+ samples, proper doping of Li+–Zn2+ leads to an drastic increase of the UC luminescence centered at 560 nm by a factor of 28. The UC luminescence enhancement is a result of the increased lifetime of the intermediate state 4I11/2 (Er). The intensity ratio of the green over red emissions (green/red) is also affected by the codoping of Zn2+, Li+ and Li+–Zn2+ ions. Our results demonstrated that the Li+–Zn2+ codoping in Y2O3:Er3+ phosphors produced remarkable enhancement of the UC luminescence and green/red ratio, making this nanocrystal a promising candidate for photonic and biological applications.

.Figure optionsDownload as PowerPoint slideResearch highlights▶ Li+–Zn2+ ions codoping in Y2O3:Er3+ phosphors produced remarkable enhancement of the UC luminescence and green/red ratio. ▶ Codoping Li+–Zn2+ ions can decrease the OH groups in the nanocrystals and increase the lifetime of the intermediate state I11/24 (Er).