Synthesis of Uniform Disk-Shaped Copper Telluride Nanocrystals and Cation Exchange to Cadmium Telluride Quantum Disks with Stable Red Emission
Synthesis of Uniform Disk-Shaped Copper Telluride Nanocrystals and Cation Exchange to Cadmium Telluride Quantum Disks with Stable Red Emission
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DOI：
10.1021/ja404694k
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发表时间：
2013-08-21
影响因子：
15
通讯作者：
Moreels, Iwan
中科院分区：
文献类型：
--
作者：
Li, Hongbo;Brescia, Rosaria;Moreels, Iwan
我们提出了一个定义良好的化学计量组成和可调的直径和厚度的新型盘形六角Cu 2 Te纳米晶体的合成。随后在高温（180 ℃）下Cu与Cd的阳离子交换导致高荧光CdTe纳米晶体，晶格中残留的Cu小于1 mol 96。该过程保留了整体盘的形状，但伴随着大量的阴离子亚晶格的重建，导致从表面法线在Cu 2 Te到在CdTe纳米盘的盘平面的c-轴的重新取向。合成的CdTe纳米盘显示出连续可调的光致发光（PL）峰位置，与磁盘的厚度缩放。的PL寿命进一步证实，CdTe PL来自带边激子复合，也就是说，没有观察到铜相关的发射。平均而言，复合速率相对于它们的球形量子点对应物快约25-45%，从而打开了通过控制球形形状来增强给定波长下的发射速率的可能性。最后，PL量子效率高达36%和增强的PL稳定性在环境条件下，由于在阳离子交换过程中形成的CdS的单分子层的表面上，这些平坦的量子盘形成一个有趣的富集到目前的家庭的高荧光，形状控制的纳米晶体。
We present the synthesis of novel disk-shaped hexagonal Cu2Te nanocrystals with a well-defined stoichiometric composition and tunable diameter and thickness. Subsequent cation exchange of Cu to Cd at high temperature (180 degrees C) results in highly fluorescent CdTe nanocrystals, with less than 1 mol 96 of residual Cu remaining in the lattice. The procedure preserves the overall disk shape, but is accompanied by a substantial reconstruction of the anion sublattice, resulting in a reorientation of the c-axis from the surface normal in Cu2Te into the disk plane in CdTe nanodisks. The synthesized CdTe nanodisks show a continuously tunable photoluminescence (PL) peak position, scaling with the thickness of the disks. The PL lifetime further confirms that the CdTe PL arises from band-edge exciton recombination; that is, no Cu-related emission is observed. On average, the recombination rate is about 25-45% faster with respect to their spherical quantum dots counterparts, opening up the possibility to enhance the emission rate at a given wavelength by controlling the nanocrystal shape. Finally, with a PL quantum efficiency of up to 36% and an enhanced PL stability under ambient conditions due to a monolayer of CdS formed on the nanocrystal surface during cation exchange, these flat quantum disks form an interesting enrichment to the current family of highly fluorescent, shape-controlled nanocrystals.