Cooperative and non-cooperative sensitization upconversion in lanthanide-doped LiYbF4 nanoparticles.
Cooperative and non-cooperative sensitization upconversion in lanthanide-doped LiYbF4 nanoparticles.
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DOI：
10.1039/c7nr02124k
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发表时间：
2017-05
期刊：
影响因子：
6.7
通讯作者：
Qilin Zou;Ping Huang;Wei Zheng;Wenwu You;Renfu Li;Datao Tu;Jin Xu;Xueyuan Chen
中科院分区：
文献类型：
--
作者：
Qilin Zou;Ping Huang;Wei Zheng;Wenwu You;Renfu Li;Datao Tu;Jin Xu;Xueyuan Chen
稀土(Ln3+)掺杂的上转换纳米粒子(UCNPs)因其潜在的生物应用而引起了人们的极大兴趣。然而，胶体Ln3+掺杂UCNPs中的上转换(UC)，特别是协同敏化UC(CSU)的本征光物理机制至今仍未被触及。在这里，我们报道了一种独特的合成高质量LiYbF4：LN3+核/壳UCNP的策略，该UCNP具有可调的颗粒尺寸和壳层厚度。在980 nm激发下，研究了Er3+、Ho3+和Tm3+的能量转移Uc和Tb3+的CSU。通过表面钝化，我们获得了高效的非合作敏化UC，对Er3+、Ho3+和Tm3+的绝对量子产率(QYS)分别为3.36%、0.69%和0.81%。特别是在功率密度为70W·cm~(-2)的激发下，我们首次定量测量了Tb~(3+)的CSU效率，其绝对量子效率为0.0085%。利用随温度变化的稳态和瞬时UC谱，我们揭示了LiYbF4：Tb3+UCNPs中CSU过程中声子辅助的协同能量转移(T&gT；100K)和顺序二聚体基态吸收/激发态吸收(T<；100K)的主要机制。
Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) have attracted tremendous interest owing to their potential bioapplications. However, the intrinsic photophysics responsible for upconversion (UC) especially the cooperative sensitization UC (CSU) in colloidal Ln3+-doped UCNPs has remained untouched so far. Herein, we report a unique strategy for the synthesis of high-quality LiYbF4:Ln3+ core-only and core/shell UCNPs with tunable particle sizes and shell thicknesses. Energy transfer UC from Er3+, Ho3+ and Tm3+ and CSU from Tb3+ were comprehensively surveyed under 980 nm excitation. Through surface passivation, we achieved efficient non-cooperative sensitization UC with absolute UC quantum yields (QYs) of 3.36%, 0.69% and 0.81% for Er3+, Ho3+ and Tm3+, respectively. Particularly, we for the first time quantitatively determined the CSU efficiency for Tb3+ with an absolute QY of 0.0085% under excitation at a power density of 70 W cm-2. By means of temperature-dependent steady-state and transient UC spectroscopy, we unraveled the dominant mechanisms of phonon-assisted cooperative energy transfer (T > 100 K) and sequential dimer ground-state absorption/excited-state absorption (T < 100 K) for the CSU process in LiYbF4:Tb3+ UCNPs.