Structure-property correlation of CdSe clusters using experimental results and first-principles DFT calculations
Structure-property correlation of CdSe clusters using experimental results and first-principles DFT calculations
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DOI：
10.1021/ja0565018
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发表时间：
2006-01-18
影响因子：
15
通讯作者：
Ishikawa, M
中科院分区：
文献类型：
--
作者：
Jose, R;Zhanpeisov, NU;Ishikawa, M
通过结合实验吸收、光致发光（PL）和X射线衍射（XRD）光谱以及从头算密度泛函（DFT）计算，研究了直径接近2 nm的CdSe量子点（团簇）的结构和性质.这些CdSe簇成核，并从含有相应的镉和硒前体的溶液中生长的热注入技术，允许一个获得的PL效率高达0.5的尺寸控制的CdSe簇。在B3 LYP/LanI 2dz水平上进行DFT计算，然后进行时间依赖的TDDFT计算以估计n个能量单重态跃迁。这些实验和理论研究的结果的基础上，一种方法，以确定是否拟议的集群具有类似的平均直径为2 nm的物理上更合理的讨论。结果表明，CdSe团簇的最小成核为六元环平面结构的（CdSe）（3）。对于该结构没有观察到PL。下一个稳定团簇的形成取决于是否使用十六胺（HDA）用于CdSe团簇的生长。在不存在HDA的情况下，发现第二簇是（CdSe）（6），其特征在于具有宽的PL光谱，而在存在HDA的情况下，发现其是（CdSe）（n）（其中n ≥ 14），具有尖锐的PL光谱。
Structures and properties of CdSe quantum dots (clusters) up to a diameter of similar to 2 nm were investigated by combining experimental absorption, photoluminescence (PL), and X-ray diffraction (XRD) spectroscopies as well as ab initio DFT calculations. These CdSe clusters were nucleated and grown from solutions containing respective cadmium and selenium precursors following the hot-injection technique that allows one to obtain size-controlled CdSe clusters having PL efficiency up to 0.5. The DFT calculations were performed at the B3LYP/LanI2dz level and followed by time-dependent TDDFT calculations to estimate n energy singlet transitions. On the basis of the results of these experimental and theoretical studies, an approach to determine whether the proposed cluster with a mean diameter of similar to 2 nm is more physically reasonable is discussed. It was shown that the minimum nucleus of a CdSe cluster consists of (CdSe)(3) with a six-membered ring and planar structure. No PL is observed for this structure. The formation of the next stable cluster depends on whether hexadecylamine (HDA) was used for the growth of the CdSe clusters. In the absence of HDA, the second cluster was found to be (CdSe)(6) characterized by a broad PL spectrum, while in the presence of HDA, it was found to be (CdSe)(n) (where n >= 14) with a sharp PL spectrum.