PbSe/CdSe Thin-Shell Colloidal Quantum Dots
PbSe/CdSe Thin-Shell Colloidal Quantum Dots
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DOI：
10.1515/zpch-2014-0625
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发表时间：
2015-02
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影响因子：
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通讯作者：
Gary Zaiats;Diana Yanover;R. Vaxenburg;A. Shapiro;A. Safran;Inbal Hesseg;A. Sashchiuk;E. Lifshitz
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文献类型：
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作者：
Gary Zaiats;Diana Yanover;R. Vaxenburg;A. Shapiro;A. Safran;Inbal Hesseg;A. Sashchiuk;E. Lifshitz
本文研究了PbSe和PbSe/CdSe胶体量子点(CQD)的结构和光学性质，后者是通过Pb2+与Cd2+离子的阳离子交换而形成的。阳离子交换发生在择优晶面上，形成非同心的CdSe壳层或PbxCd1-xSe合金化壳层。得到的异质结构称为PbSe/CdSe“薄壳”CQD。母体PbSe CQD的直径较小，为3-4 nm，吸收边在1.0-1.3 eV之间。在不同温度下记录的稳态和时间分辨光致发光光谱揭示了PbSe/CdSe CQD的以下性质：(1)无空气CQD在氧气中保持光致发光强度；(2)带边激子寿命相对于母体PbSe CQD延长约2倍。实验结果和有效的基于质量的计算表明了合金化壳层的形成，并突出了中心偏离CQD中心的芯位移对异质结构光学性质的显著影响。
Abstract The present work describes the structural and optical characterization of PbSe and PbSe/CdSe colloidal quantum dots (CQDs), the latter being produced by cation exchange of Pb2+ for Cd2+ ions. The cation exchange occurs on preferred crystallographic facets and results in either non-concentric CdSe shells or PbxCd1–xSe alloyed-shell layers. The obtained heterostuctures are referred to as PbSe/CdSe “thin shell” CQDs. The parent PbSe CQDs are limited to relatively small diameters of 3–4 nm, with absorption edge between 1.0 and 1.3 eV. The steady-state and time-resolved photoluminescence spectra recorded at various temperatures reveal the following properties of the PbSe/CdSe CQDs: (1) the photoluminescence intensity of air-free CQDs is maintained upon their exposure to oxygen; (2) the band-edge exciton lifetime is extended by about a factor of two relative to the parent PbSe CQDs. The experimental results and the effective mass-based calculations suggest the formation of alloyed shells and highlight a pronounced effect of core displacement from the CQD center on the heterostructure optical properties.