Koo Ja-Jung, Jung Kwang Hwan, Park Kyungsu, Min Won Ja, Yu Kyu-Sang, Kim Zee Hwan, Lee Jin-Kyu
Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea.
K-MAC, Yongsan-Dong 554, Yueseong-Gu, Daejeon 305-500, Republic of Korea.
J Phys Chem Lett. 2022 Aug 11;13(31):7220-7227. doi: 10.1021/acs.jpclett.2c01923. Epub 2022 Jul 30.
Core/shell quantum dots (QDs) have been extensively studied, yet their optical properties widely vary among studies. Such variation may arise from the variation in interfacial structures induced by the subtle difference in each synthetic procedure. Here, we studied the interfacial structures of CdSe/ZnS QDs using the time-of-flight medium energy ion-scattering spectroscopy (TOF-MEIS), which offers the radial elemental distributions as well as the overall elemental compositions of QDs. The TOF-MEIS spectra provided strong evidence for the existence of an alloyed layer at the interface between CdSe and ZnS in typical CdSe/ZnS QDs. On the basis of the emission and absorption spectra of QDs sampled during the synthesis, we conclude that such interfacial alloying is caused by the dissolution of CdSe seeds during the synthesis steps. Such a dissolution mechanism is further corroborated by the observation that the ligand environment of solvent (X or L type) leads to different shapes of interfaces.
核壳量子点（QDs）已得到广泛研究，但其光学性质在不同研究中差异很大。这种差异可能源于每种合成方法中细微差异所导致的界面结构变化。在此，我们使用飞行时间中能离子散射光谱（TOF-MEIS）研究了CdSe/ZnS量子点的界面结构，该光谱可提供量子点的径向元素分布以及整体元素组成。TOF-MEIS光谱为典型CdSe/ZnS量子点中CdSe与ZnS界面处存在合金层提供了有力证据。基于合成过程中采样的量子点的发射光谱和吸收光谱，我们得出结论，这种界面合金化是由合成步骤中CdSe晶种的溶解引起的。溶剂的配体环境（X型或L型）导致不同形状的界面这一观察结果进一步证实了这种溶解机制。
