Santra Pralay K, Viswanatha Ranjani, Daniels Steve M, Pickett Nigel L, Smith Jason M, O'Brien Paul, Sarma D D
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
J Am Chem Soc. 2009 Jan 21;131(2):470-7. doi: 10.1021/ja8033075.
In this paper, we report on the growth and characterization of quantum dot-quantum well nanostructures with photoluminescence (PL) that is tunable over the visible range. The material exhibits a PL efficiency as high as approximately 60% and is prepared by reacting ZnS nanocrystals in turn with precursors for CdSe and ZnS in an attempt to form a simple "ZnS/CdSe/ZnS quantum-well structure". Through the use of synchrotron radiation-based photoelectron spectroscopy in conjunction with detailed overall compositional analysis and correlation with the size of the final composite nanostructure, the internal structure of the composite nanocrystals is shown to consist of a graded alloy core whose composition gradually changes from ZnS at the very center to CdSe at the onset of a CdSe layer. The outer shell is ZnS with a sharp interface, probably reflecting the relative thermodynamic stabilities of the parent binary phases. These contrasting aspects of the internal structure are discussed in terms of the various reactivities and are shown to be crucial for understanding the optical properties of such complex heterostructured nanomaterials.
在本文中，我们报道了具有在可见光范围内可调谐光致发光（PL）的量子点-量子阱纳米结构的生长和特性。该材料表现出高达约60%的PL效率，它是通过使硫化锌（ZnS）纳米晶体依次与硒化镉（CdSe）和硫化锌的前驱体反应制备而成，旨在形成一种简单的“ZnS/CdSe/ZnS量子阱结构”。通过结合基于同步辐射的光电子能谱与详细的整体成分分析以及与最终复合纳米结构尺寸的相关性，复合纳米晶体的内部结构显示为由渐变合金核组成，其成分从最中心的ZnS逐渐变化到CdSe层开始处的CdSe。外壳是具有清晰界面的ZnS，这可能反映了母体二元相的相对热力学稳定性。内部结构的这些不同方面根据各种反应性进行了讨论，并表明对于理解此类复杂异质结构纳米材料的光学性质至关重要。
