Structure-Property Correlation of CdSe Clusters Using Experimental Results and First-Principles DFT Calculations

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• 作者：Rajan Jose ; Nurbosyn U. Zhanpeisov ; Hiroshi Fukumura ; Yoshinobu Baba ; and Mitsuru Ishikawa
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：January 18, 2006
• 年：2006
• 卷：128
• 期：2
• 页码：629 - 636
• 全文大小：387K
• 年卷期：v.128,no.2(January 18, 2006)
• ISSN：1520-5126

文摘

Structures and properties of CdSe quantum dots (clusters) up to a diameter of ~2 nm wereinvestigated 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 fromsolutions containing respective cadmium and selenium precursors following the hot-injection techniquethat allows one to obtain size-controlled CdSe clusters having PL efficiency up to 0.5. The DFT calculationswere performed at the B3LYP/Lanl2dz level and followed by time-dependent TDDFT calculations to estimaten energy singlet transitions. On the basis of the results of these experimental and theoretical studies, anapproach to determine whether the proposed cluster with a mean diameter of ~2 nm is more physicallyreasonable is discussed. It was shown that the minimum nucleus of a CdSe cluster consists of (CdSe)₃with a six-membered ring and planar structure. No PL is observed for this structure. The formation of thenext 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.