A novel strategy for markedly enhancing the red upconversion emission in Er3+/Tm3+ cooperated nanoparticles
A novel strategy for markedly enhancing the red upconversion emission in Er3+/Tm3+ cooperated nanoparticles
复制标题
一种显着增强 Er3 /Tm3 配合纳米粒子红光上转换发射的新策略
DOI：
10.1039/c8tc02370k
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发表时间：
2018
影响因子：
6.4
通讯作者：
Yang Piaoping
中科院分区：
文献类型：
--
作者：
Xu Jiating;Yang Dan;Han Wei;Dong Shuming;Jia Tao;He Fei;Bi Huiting;Gai Shili;Li Li;Yang Piaoping
一种具有反斯托克斯性质的稀土基上转换纳米晶体因其独特的物理性质而引起了世界各国的关注。本文提出了一种新型的核-活性壳层上转换纳米晶体(NaErF4：Tm@NaGdF4：Yb)，在980 nm的近红外(NIR)激光激发下，发射出超亮的红光。Er3+离子既是敏化剂又是激活剂，能够实现核心纳米晶体的高效上转换过程。为了缓解Er~(3+)离子与内部晶格缺陷之间的能量迁移引起的发光猝灭，在晶核中引入Tm~(3+)的能量陷阱中心，通过能量回传(Er3+→Tm~(3+)→Er3+)途径限制Er~(3+)的能量。之后，在核心区生长了一层活性壳层NaGdF4：YB，使近红外光子有效地传递到上转换子区，同时抑制了由表面缺陷和表面相关配体引起的发光猝灭。值得注意的是，Tm3+和活性壳层都可以提高Er3+发光的红绿比(R/G)，从而产生高纯度的超亮红色发射。核活性壳层纳米粒子比核惰性壳层纳米粒子(∼：Tm@NaGdF4)具有更强的发射强度(比核惰性壳层纳米粒子高20倍)，量子产率高达3.71%。这一发现为获得高纯度的红光上转换纳米晶提供了一条简便的途径。
A rare-earth-based upconversion nanocrystal that exhibits anti-Stokes nature has attracted worldwide attention due to its unique physical properties. In this work, a novel core–active shell upconversion nanocrystal (NaErF4:Tm@NaGdF4:Yb) which emits super-bright red emission upon 980 nm near-infrared (NIR) laser excitation is presented. The Er3+ ions act as both sensitizers and activators to enable an efficient upconversion process of core nanocrystals. To mitigate the luminescence quenching caused by the energy migration between the Er3+ ions and internal lattice defects, an energy trapping center of Tm3+ was introduced into the core to confine the energy of Er3+ through an energy back transfer (Er3+ → Tm3+ → Er3+) pathway. After that, an active shell of NaGdF4:Yb was grown on the core zone to simultaneously enable the efficient energy transfer from NIR photons to the upconverting zone and suppress the luminescence quenching caused by surface defects and surface associated ligands. It is worth noting that both the Tm3+ and active shell can enhance the red to green (R/G) ratio of the Er3+ emission, thus resulting in an ultra-bright red emission with high purity. The core–active shell nanoparticles possess more intense (∼20 times higher) emission intensity than core–inert shell nanoparticles (NaErF4:Tm@NaGdF4), and their quantum yield reaches as high as 3.71%. This finding paves a convenient way to obtain red-emissive upconversion nanocrystals with high purity for special applications.