The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles （UCNPs）. However, the serious concentration quenching in highly doped UCNPs remains...The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles （UCNPs）. However, the serious concentration quenching in highly doped UCNPs remains a vital restriction for further enhanced upconversion luminescence （UCL）. Herein, we examined the effect of temperature on the concentration quenching of rare-earth UCNPs, an issue that has been overlooked, and we show that it is significant for biomedical or optical applications of UCNPs. In this work, we prepared a series of UCNPs by doping Er3. luminescent centers at different concentrations in a NaLuF4：Yb3＋ matrix. At room temperature （298 K）, steady-state photoluminescence （PL） spectroscopy showed substantial concentration quenching of the Er~ emission with increasing doping concentrations. However, the concentration quenching effect was no longer effective at lower temperatures. Kinetic curves obtained from time-resolved PL spectroscopy further showed that the concen- tration quenching dynamics were vitally altered in the cryogenic temperature region, i.e., below 160 K. Our work on the temperature-switchable concentration quenching mechanism may shed light on improving UCL properties, promoting their practical applications.展开更多
基金This work was supported by the National Natural Science Foundation of China （Nos. 21373268, 21301121, and 21227803）, the open funding of Renmin University of China （Nos. 15XNLQ04 and 10XNI007）, and the open funding of the State Key Laboratory on Integrated Optoelectronics of Jilin University （No. IOSKL2015KF33）.
文摘The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles （UCNPs）. However, the serious concentration quenching in highly doped UCNPs remains a vital restriction for further enhanced upconversion luminescence （UCL）. Herein, we examined the effect of temperature on the concentration quenching of rare-earth UCNPs, an issue that has been overlooked, and we show that it is significant for biomedical or optical applications of UCNPs. In this work, we prepared a series of UCNPs by doping Er3. luminescent centers at different concentrations in a NaLuF4：Yb3＋ matrix. At room temperature （298 K）, steady-state photoluminescence （PL） spectroscopy showed substantial concentration quenching of the Er~ emission with increasing doping concentrations. However, the concentration quenching effect was no longer effective at lower temperatures. Kinetic curves obtained from time-resolved PL spectroscopy further showed that the concen- tration quenching dynamics were vitally altered in the cryogenic temperature region, i.e., below 160 K. Our work on the temperature-switchable concentration quenching mechanism may shed light on improving UCL properties, promoting their practical applications.
