3D assembly of silica encapsulated semiconductor nanocrystals.
3D assembly of silica encapsulated semiconductor nanocrystals.
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DOI：
10.1039/c5nr01880c
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发表时间：
2015-07
期刊：
影响因子：
6.7
通讯作者：
Christin Rengers;S. Voitekhovich;Susann Kittler;A. Wolf;Marion Adam;N. Gaponik;S. Kaskel;A. Eychmüller
中科院分区：
文献类型：
--
作者：
Christin Rengers;S. Voitekhovich;Susann Kittler;A. Wolf;Marion Adam;N. Gaponik;S. Kaskel;A. Eychmüller
无序多孔网络，即所谓的气凝胶，可以通过量子点 (QD) 的 3D 组装来实现。这些材料非常适合光子应用，但是在这些结构中观察到光致发光（PL）强度的一定猝灭。这种PL猝灭主要归因于网络中纳米颗粒的紧密接触所产生的能量转移机制。在这里，我们展示了通过四唑封端二氧化硅封装的量子点的非经典、可逆凝胶形成，形成一种具有非猝灭PL行为的新型气凝胶材料。通过光谱监测凝胶/脱凝胶表明，与原始胶体溶液相比，纳米晶体的光学特性可以保留在 3D 网络中，因为在凝胶中没有观察到由于 QD 之间的耦合而导致的光谱偏移和寿命缩短。与其他量子点二氧化硅整体相比，我们凝胶中的量子点均匀分布，具有明显且可控的距离。此外，我们还表明二氧化硅壳是多孔的，允许金属离子穿过壳并与量子点核相互作用，导致发射特性发生可检测的变化。我们进一步展示了这种凝胶方法对其他量子点材料的适用性，这为轻松制备各种混合凝胶结构奠定了基础。
Non-ordered porous networks, so-called aerogels, can be achieved by the 3D assembly of quantum dots (QDs). These materials are well suited for photonic applications, however a certain quenching of the photoluminescence (PL) intensity is observed in these structures. This PL quenching is mainly attributed to the energy transfer mechanisms that result from the close contact of the nanoparticles in the network. Here, we demonstrate the formation of a novel aerogel material with non-quenching PL behaviour by non-classical, reversible gel formation from tetrazole capped silica encapsulated QDs. Monitoring of the gelation/degelation by optical spectroscopy showed that the optical properties of the nanocrystals could be preserved in the 3D network since no spectral shifts and lifetime shortening, which can be attributed to the coupling between QDs, are observed in the gels as compared to the original colloidal solutions. In comparison with other QD-silica monoliths, QDs in our gels are homogeneously distributed with a distinct and controllable distance. In addition we show that the silica shell is porous and allows metal ions to pass through the shell and interact with the QD core causing detectable changes of the emission properties. We further show the applicability of this gelation method to other QD materials which sets the stage for facile preparation of a variety of mixed gel structures.