Yang Xu, Yuan Maohui, Wang Rui, Zhao Xiaofan, Yang Zining, Han Kai, Wang Hongyan, Xu Xiaojun
College of Advanced Interdisciplinary Studies, National University of Defence Technology Changsha 410073 China
Hunan Provincial Key Laboratory of High Energy Laser Technology, National University of Defence Technology Changsha 410073 China.
RSC Adv. 2019 Apr 30;9(23):13201-13206. doi: 10.1039/c9ra02232e. eCollection 2019 Apr 25.
Harnessing the color tuning capability of upconversion nanoparticles (UCNPs) is of great significance in the field of advanced bioimaging and color display. Here, we report the tunable size and upconversion luminescence (UCL) multicolor in CaF:Yb/Ho/Ce UCNPs, which were synthesized by a facile hydrothermal method. It was found that the size of these UCNPs could be controlled (from 600 to 30 nm) by varying the concentration of Ce ions. Under the excitation of a 980 nm continuous-wave (CW) laser, the UCL color of these UCNPs can be tuned from green to red as the doped Ce ions gradually increase from 0 to 10 mol% and the red-to-green (R/G) ratio is enhanced remarkably. It is suggested that the cross-relaxation (CR) processes between Ho and Ce ions contribute to the tunable multicolor and enhancement of the R/G ratio. The mechanism of these processes is well supported by the time-resolved decay and near infrared (NIR) emission measurements.
利用上转换纳米粒子（UCNPs）的颜色调节能力在先进生物成像和彩色显示领域具有重要意义。在此，我们报道了通过简便水热法合成的CaF:Yb/Ho/Ce UCNPs中可调节的尺寸和上转换发光（UCL）多色性。研究发现，通过改变Ce离子浓度可以控制这些UCNPs的尺寸（从600纳米到30纳米）。在980纳米连续波（CW）激光激发下，随着掺杂的Ce离子从0逐渐增加到10摩尔%，这些UCNPs的UCL颜色可从绿色调至红色，且红/绿（R/G）比显著增强。研究表明，Ho和Ce离子之间的交叉弛豫（CR）过程有助于实现可调节的多色性和R/G比的增强。时间分辨衰减和近红外（NIR）发射测量很好地支持了这些过程的机制。
