Freyer Abigail, Tumiel Trevor M, Smeaton Michelle, Savitzky Benjamin H, Kourkoutis Lena F, Krauss Todd D
Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, United States.
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.
ACS Nanosci Au. 2023 Apr 25;3(4):280-285. doi: 10.1021/acsnanoscienceau.3c00010. eCollection 2023 Aug 16.
Cation exchange is becoming extensively used for nanocrystal (NC) doping in order to produce NCs with unique optical and electronic properties. However, despite its ever-increasing use, the relationships between the cation exchange process, its doped NC products, and the resulting NC photophysics are not well characterized. For example, similar doping procedures on NCs with the same chemical compositions have resulted in quite different photophysics. Through a detailed single molecule investigation of a postsynthesis Ag doping of CdSe NCs, a number of species were identified within a single doped NC sample, suggesting the differences in the optical properties of the various synthesis methods are due to the varied contributions of each species. Electrostatic force microscopy (EFM), electron energy loss spectroscopy (EELS) mapping, and single molecule photoluminescence (PL) studies were used to identify four possible species resulting from the Ag-CdSe cation exchange doping process. The heterogeneity of these samples shows the difficulty in controlling a postsynthesis cation exchange method to produce homogeneous samples needed for use in any potential application. Additionally, the heterogeneity in the doped samples demonstrates that significant care must be taken in describing the ensemble or average characteristics of the sample.
阳离子交换正被广泛用于纳米晶体（NC）掺杂，以制备具有独特光学和电子特性的纳米晶体。然而，尽管其应用日益广泛，但阳离子交换过程、其掺杂的纳米晶体产物以及由此产生的纳米晶体光物理性质之间的关系尚未得到很好的表征。例如，对具有相同化学成分的纳米晶体进行类似的掺杂程序，却导致了截然不同的光物理性质。通过对合成后CdSe纳米晶体进行银掺杂的详细单分子研究，在单个掺杂纳米晶体样品中鉴定出了多种物质，这表明各种合成方法的光学性质差异是由于每种物质的贡献不同所致。利用静电力显微镜（EFM）、电子能量损失谱（EELS）映射和单分子光致发光（PL）研究，确定了银-镉硒阳离子交换掺杂过程产生的四种可能物质。这些样品的异质性表明，难以控制合成后阳离子交换方法来制备用于任何潜在应用所需的均匀样品。此外，掺杂样品中的异质性表明，在描述样品的整体或平均特性时必须格外小心。
