Breakdown of Volume Scaling in Auger Recombination in CdSe/CdS Heteronanocrystals: The Role of the Core-Shell Interface
Breakdown of Volume Scaling in Auger Recombination in CdSe/CdS Heteronanocrystals: The Role of the Core-Shell Interface
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DOI：
10.1021/nl103801e
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发表时间：
2011-02-01
期刊：
影响因子：
10.8
通讯作者：
Klimov, Victor I.
中科院分区：
文献类型：
--
作者：
Garcia-Santamaria, Florencio;Brovelli, Sergio;Klimov, Victor I.
半导体纳米晶体（NC）中电子激发的空间限制导致非辐射俄歇复合（AR）的显著增强，使得AR过程可以容易地主导多激子的衰变。AR对NC的激光应用特别有害，因为这些结构中的光学增益明显依赖于多激子态的发射。在标准NC中，AR率与NC体积的倒数呈线性关系。在这里，我们调查多激子动力学异质核的CdSe核心和CdS壳层的厚度可调组成的纳米碳。我们观察到在壳生长的初始阶段，AR率急剧下降，这不能单独用传统的体积缩放来解释。相反地，荧光线窄化研究表明，AR的抑制与核壳界面合金层的形成有关，这表明这种效应主要来自“平滑”这些数据强调了NC界面结构在AR过程中的重要性，并为开发具有抑制AR的新纳米结构提供了一般指导方针，未来的激光应用
Spatial confinement of electronic excitation,in, semiconductor nanocrystals (NCs) results in a significant enhancement of nonradiative Auger recombination (AR), such that AR processes can easily dominate the decay of multiexcitons. AR is especially detrimental to lasing applications of NCs, as optical gain in these structures explicitly relies on emission from multiexciton states. In standard NCs, AR rates scale linearly with inverse NC volume. Here, we investigate multiexciton dynamics in hetero-NCs composed of CdSe cores and CdS shells of tunable thickness. We observe a dramatic decrease in the AR rates at the initial stage of shell growth, which cannot be explained by traditional volume scaling alone. Rather, fluorescence-line-narrowing studies indicate that the suppression of AR correlates with the formation of an alloy layer at the core shell interface suggesting that this effect derives primarily from the "smoothing" of the Confinement potential associated with interfacial alloying These data highlight the importance of NC interfacial structure in the AR process and provide general guidelines for the development of new nanostructures with suppressed AR for future lasing applications.