Effects of Core Size and Shell Thickness on Luminescence Dynamics of Wurtzite CdSe/CdS Core/Shell Nanocrystals
Effects of Core Size and Shell Thickness on Luminescence Dynamics of Wurtzite CdSe/CdS Core/Shell Nanocrystals
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DOI：
10.1021/jp3014018
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发表时间：
2012-07
影响因子：
3.7
通讯作者：
Huichao Zhang;Y. Ye;Jiayu Zhang;Yiping Cui;Boping Yang;Li Shen
中科院分区：
文献类型：
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作者：
Huichao Zhang;Y. Ye;Jiayu Zhang;Yiping Cui;Boping Yang;Li Shen
在尺寸分别为2.8、3.8和4.9 nm的胶体CdSe纳米晶(NCS)上连续包覆了单分子层(MLS)。X-射线衍射图表明，纤锌矿CdSe晶核的应力随着CdS壳层的外延生长而增加，而对晶核尺寸敏感的CdSe晶格收缩不会随着CDS壳层向5mls的方向释放。研究了CdSe晶核尺寸和CdS壳层厚度对光致发光(PL)寿命的影响。光致发光寿命随温度的波动表明了陷阱态的空间分布，即使在具有5ML Cd壳层的NCS的情况下，本征激子与表面陷阱之间的强烈相互作用也可以被激活。
Colloidal CdSe nanocrystals (NCs), whose size is 2.8, 3.8, and 4.9 nm, respectively, were successively overcoated with CdS monolayers (MLs). The X-ray diffraction patterns indicated that the stress in the wurtzite CdSe core was increased with the epitaxial growth of CdS shell, and the CdSe lattice contraction, which was sensitive to core size, did not release with the CdS shell toward 5 MLs. The effects of the CdSe core size and the CdS shell thickness on the temperature-dependent photoluminescence (PL) lifetime were investigated. The PL lifetime undulation with temperature is indicative of the spatial distribution of trap states, and the strong interplay between intrinsic excitons and surface traps can be activated even in the case of the NCs with 5 ML CdS shell.