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The nature of non-FRET photoluminescence quenching in nanoassemblies from semiconductor quantum dots and dye molecules†
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2018-06-21 00:00:00 , DOI: 10.1039/c8cp02846j Aleksander P. Stupak 1, 2, 3, 4 , Thomas Blaudeck 5, 6, 7, 8 , Eduard I. Zenkevich 4, 9, 10, 11 , Stefan Krause 5, 6, 7, 8 , Christian von Borczyskowski 5, 6, 7, 8
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2018-06-21 00:00:00 , DOI: 10.1039/c8cp02846j Aleksander P. Stupak 1, 2, 3, 4 , Thomas Blaudeck 5, 6, 7, 8 , Eduard I. Zenkevich 4, 9, 10, 11 , Stefan Krause 5, 6, 7, 8 , Christian von Borczyskowski 5, 6, 7, 8
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Nanoassemblies formed via self-assembly based on colloidal CdSe quantum dots (QDs) and porphyrin (H2P) dye molecules show Fluorescence Resonant Energy Transfer (FRET) and non-FRET quenching of QD photoluminescence (PL). We present a procedure to unravel and quantify these two relaxation pathways via dynamic and static PL quenching experiments. Accordingly, FRET amounts at maximum to 10% of the total quenching efficiency. Since the degree of ligand coverage is inhomogeneously distributed across the QD ensemble PL quantum yields vary broadly. The attachment of H2P molecules occurs preferentially to those QDs with low ligand coverage. Along with that, nanoassembly formation deviates strongly from Poisson statistics. Like FRET, non-FRET depends on the QD size. We assign non-FRET quenching to the formation of specific new Cd2+ trap states following depletion of several ligands by the spacious dye molecules. While FRET follows quantitatively the Förster model, non-FRET appears on time scales of 1–3 ns in new and enhanced non-radiative near-band-edge QD PL decay channels caused by a trapping of the electrons in long-lived intra-gap states which then manifests itself in a subsequent weak PL emission. We assign the related intra-band emission to a recombination of deep-trap electrons and shallow-trap holes.
中文翻译：
半导体量子点和染料分子在纳米组件中进行非FRET光致发光淬灭的性质†
通过基于胶体CdSe量子点（QD）和卟啉（H 2 P）染料分子的自组装形成的纳米组件表现出荧光共振能量转移（FRET）和QD光致发光（PL）的非FRET猝灭。我们提出了一个程序，通过动态和静态PL淬灭实验来阐明和量化这两个松弛途径。因此，FRET最大为总淬灭效率的10％。由于配体覆盖的程度在QD整体PL中不均匀分布，因此量子产率差异很大。H 2的附件P分子优先于那些配体覆盖率低的QD出现。随之而来的是，纳米组装体的形成与泊松统计有很大的不同。像FRET一样，非FRET取决于QD大小。我们将非FRET猝灭指定为特定的新Cd 2+捕集态的形成，这些状态将由宽敞的染料分子耗尽几个配体后产生。尽管FRET定量地遵循Förster模型，但在长寿命的内部带隙中捕获电子会导致新的和增强的无辐射近带边缘QD PL衰变通道中1 ns到3 ns的时间尺度上出现非FRET状态，然后在随后的弱PL排放中表现出来。我们将相关的带内发射分配给深陷阱电子和浅陷阱空穴的复合。
更新日期：2018-06-21
中文翻译：
半导体量子点和染料分子在纳米组件中进行非FRET光致发光淬灭的性质†
通过基于胶体CdSe量子点（QD）和卟啉（H 2 P）染料分子的自组装形成的纳米组件表现出荧光共振能量转移（FRET）和QD光致发光（PL）的非FRET猝灭。我们提出了一个程序，通过动态和静态PL淬灭实验来阐明和量化这两个松弛途径。因此，FRET最大为总淬灭效率的10％。由于配体覆盖的程度在QD整体PL中不均匀分布，因此量子产率差异很大。H 2的附件P分子优先于那些配体覆盖率低的QD出现。随之而来的是，纳米组装体的形成与泊松统计有很大的不同。像FRET一样，非FRET取决于QD大小。我们将非FRET猝灭指定为特定的新Cd 2+捕集态的形成，这些状态将由宽敞的染料分子耗尽几个配体后产生。尽管FRET定量地遵循Förster模型，但在长寿命的内部带隙中捕获电子会导致新的和增强的无辐射近带边缘QD PL衰变通道中1 ns到3 ns的时间尺度上出现非FRET状态，然后在随后的弱PL排放中表现出来。我们将相关的带内发射分配给深陷阱电子和浅陷阱空穴的复合。
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