Demortière Arnaud, Leonard Donovan N, Petkov Valeri, Chapman Karena, Chattopadhyay Soma, She Chunxing, Cullen David A, Shibata Tomohiro, Pelton Matthew, Shevchenko Elena V
Center for Nanoscale Materials , Argonne National Laboratory , 9700 South Cass Avenue , Argonne , Illinois 60439 , United States.
Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS UMR 7314 , Université Picardie Jules Verne , 80039 Amiens , France.
J Phys Chem Lett. 2018 Apr 19;9(8):1900-1906. doi: 10.1021/acs.jpclett.8b00914. Epub 2018 Apr 2.
Colloidal semiconductor nanocrystals are commonly grown with a shell of a second semiconductor material to obtain desired physical properties, such as increased photoluminescence quantum yield. However, the growth of a lattice-mismatched shell results in strain within the nanocrystal, and this strain has the potential to produce crystalline defects. Here, we study CdSe/CdS core/shell nanorods as a model system to investigate the influence of core size and shape on the formation of stacking faults in the nanocrystal. Using a combination of high-angle annular dark-field scanning transmission electron microscopy and pair-distribution-function analysis of synchrotron X-ray scattering, we show that growth of the CdS shell on smaller, spherical CdSe cores results in relatively small strain and few stacking faults. By contrast, growth of the shell on larger, prolate spheroidal cores leads to significant strain in the CdS lattice, resulting in a high density of stacking faults.
胶体半导体纳米晶体通常会生长一层第二种半导体材料的壳层，以获得所需的物理性质，比如提高光致发光量子产率。然而，生长晶格失配的壳层会导致纳米晶体内产生应变，这种应变有可能产生晶体缺陷。在此，我们研究CdSe/CdS核壳纳米棒作为一个模型系统，以探究核尺寸和形状对纳米晶体中堆垛层错形成的影响。通过结合高角度环形暗场扫描透射电子显微镜和同步加速器X射线散射的对分布函数分析，我们发现，在较小的球形CdSe核上生长CdS壳层会导致相对较小的应变和较少的堆垛层错。相比之下，在较大的长椭球形核上生长壳层会导致CdS晶格中产生显著应变，从而产生高密度的堆垛层错。
