摘要
Lanthanide doped NaYF4 microcrystals were synthesized via a facile hydrothermal method. Multicolor upconversion luminescence was observed in NaYF4 microcrystals doped with yb^3+/Er^3+, yb^3+/Tm^3+, and yb^3+/Er^3+/Zm^3+ under the excitation of 980 nm infrared light. Importantly, the excitation power density dependence of upconversion emission intensity indicated clearly the energy transfer from Tm^3+ to Er^3+ ions under the excitation of low power density (5× 10^2× 10^2 W/cm^2). Meanwhile, the inverse energy transfer from Er^3+ to Tm^3+ ions under the excitation of relatively higher power density (4.1 × 10^4.9× 10^4 W/cm^2) was also revealed. This was a direct evidence for reversible energy transfer between Er^3+ and Tm^3+ ions. Under the excitation of high power density (4.1 ×10^4-4.9× 10^4 W/cm^2), dark sensitizers were also motivated so that the bottleneck effect of high concentration Yb^3+ ion doping was broken. This was the main reason for realizing high upconversion efficiency of the samples with heavy doping of Yb^3+ ion.
Lanthanide doped NaYF4 microcrystals were synthesized via a facile hydrothermal method. Multicolor upconversion luminescence was observed in NaYF4 microcrystals doped with yb^3+/Er^3+, yb^3+/Tm^3+, and yb^3+/Er^3+/Zm^3+ under the excitation of 980 nm infrared light. Importantly, the excitation power density dependence of upconversion emission intensity indicated clearly the energy transfer from Tm^3+ to Er^3+ ions under the excitation of low power density (5× 10^2× 10^2 W/cm^2). Meanwhile, the inverse energy transfer from Er^3+ to Tm^3+ ions under the excitation of relatively higher power density (4.1 × 10^4.9× 10^4 W/cm^2) was also revealed. This was a direct evidence for reversible energy transfer between Er^3+ and Tm^3+ ions. Under the excitation of high power density (4.1 ×10^4-4.9× 10^4 W/cm^2), dark sensitizers were also motivated so that the bottleneck effect of high concentration Yb^3+ ion doping was broken. This was the main reason for realizing high upconversion efficiency of the samples with heavy doping of Yb^3+ ion.
基金
Project supported by the National Natural Science Foundation of China(21301058,61274026)
Innovation Foundation of Hunan University of Science and Technology(S140036)