808 nm excited energy migration upconversion nanoparticles driven by a Nd3+–Trinity system with color-tunability and superior luminescence properties†,Nanoscale

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808 nm excited energy migration upconversion nanoparticles driven by a Nd3+–Trinity system with color-tunability and superior luminescence properties†
Nanoscale ( IF 5.8 ) Pub Date : 2017-12-29 00:00:00 , DOI: 10.1039/c7nr07026h
Shuai Guo _{1,

2,

3,

4} , Ming-Kiu Tsang _{2,

3,

4,

5} , Wai-Sum Lo _{1,

2,

3,

4} , Jianhua Hao _{2,

3,

4,

5} , Wing-Tak Wong _{1,

2,

3,

4}

Affiliation

We have developed energy migration upconversion (EMU) nanoparticles (UCNPs) with optimal Nd³⁺-sensitization under excitation of an 808 nm laser to avoid over-heating effects caused by a 980 nm laser while maximizing the excitation efficiency. To realize efficient 808 nm sensitization, a “Nd³⁺–Trinity system” was implemented in the energy migration upconversion (EMU) cores (NaGdF₄:Yb,Tm@NaGdF₄:Yb,X, X = Eu/Tb), resulting in a core–multishell structure of EMU cores (accumulation layer@activation layer)@transition layer@harvest layer@activation layer. The spatially separated dopants and optimized Yb³⁺/Nd³⁺ content effectively prevented severe quenching events in the UCNPs and their Nd³⁺-sensitized EMU-based photoluminescence mechanism was studied under 808 nm excitation. These Nd³⁺–Trinity EMU system UCNPs presented enhanced upconversion luminescence and prolonged lifetime compared to the 980 nm excited UCNPs of the EMU system. It is proposed that 975 nm and 1056 nm NIR photons induced from the Nd³⁺ → Yb³⁺ energy transfer facilitate the Tm³⁺ accumulation process due to the matched energy gaps, which contributes to the extended lifetimes. More importantly, the synthesized UCNPs had a small average size of sub-15 nm and they not only exhibited color-tunability via Eu³⁺/Tb³⁺ activators, but also released a larger portion of Tm³⁺ red emission at 647 nm and had better penetration ability in water under 808 nm excitation, which are favorable for bioimaging applications.

中文翻译：

由Nd ³⁺ –Trinity系统驱动的808 nm激发能量迁移上转换纳米粒子，具有色彩可调性和出色的发光性能†

我们开发了在808 nm激光激发下具有最佳Nd ³⁺敏化作用的能量迁移上转换（EMU）纳米粒子（UCNP），可在最大程度提高激发效率的同时，避免980 nm激光引起的过热效应。为了实现有效的808 nm增感，在能量迁移上转换（EMU）磁芯（NaGdF ₄：Yb，Tm @ NaGdF ₄：Yb，X，X = Eu / Tb）中实施了“ Nd ^3+-三位一体系统” ，在EMU核心的核心-多壳结构中（累积层@激活层）@过渡层@收获层@激活层。空间分离的掺杂剂和优化的Yb ³⁺ / Nd ³⁺含量可有效防止UCNPs及其Nd中的严重淬灭事件在808 nm激发下研究了基于³⁺敏化EMU的光致发光机理。与EMU系统的980 nm激发UCNP相比，这些Nd³⁺ -Trinity EMU系统UCNP具有增强的上转换发光和更长的寿命。提出了由Nd³⁺ →Yb³⁺能量转移引起的975 nm和1056 nm NIR光子由于能隙匹配而促进了Tm³⁺积累过程，这有助于延长寿命。更重要的是，合成的UCNPs的平均尺寸小于15 nm，不仅通过Eu³⁺ / Tb³⁺活化剂表现出颜色可调性，而且还释放出较大的Tm含量。647 nm处有³⁺红色发射，并且在808 nm激发下在水中具有更好的穿透能力，这对于生物成像应用是有利的。

更新日期：2017-12-29

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