Relations between the photoluminescence efficiency of CdTe nanocrystals and their surface properties revealed by synchrotron XPS
Relations between the photoluminescence efficiency of CdTe nanocrystals and their surface properties revealed by synchrotron XPS
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DOI：
10.1021/jp0352884
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发表时间：
2003-09-11
影响因子：
3.3
通讯作者：
Weller, H
中科院分区：
文献类型：
--
作者：
Borchert, H;Talapin, DV;Weller, H
用可调谐同步辐射激发的光电子能谱研究了胶体制备的硫代乙醇酸包裹的CdTe纳米晶的表面。胶体法制备的CdTe纳米晶具有依赖于生长条件的光致发光特性。考察了以不同的净生长速率制备的两种相同粒径的样品。在生长和溶解的动态平衡中缓慢生长的纳米晶具有更高的光致发光量子产率。我们进行了光电子能谱研究，以揭示纳米晶体表面是否存在结构差异，这可能解释了观察到的光致发光效率的差异。在Te-4d和Te-3d能级的高分辨光谱中确实观察到了显著的差异。与高发光纳米晶相比，低发光粒子呈现出大量的Te表面位。提出了一种可以解释发光效率差异的结构模型。
The surface of colloidally prepared CdTe nanocrystals capped with thioglycolic acid has been studied by photoelectron spectroscopy with tunable synchrotron radiation excitation. Colloidally prepared CdTe nanocrystals possess photoluminescence properties which depend on the growth conditions. Two samples of the same particle size prepared at different net growth rates were investigated. The nanocrystals which were slowly grown in a dynamic equilibrium of growth and dissolution present a much higher photoluminescence quantum yield. We have performed a photoemission study in order to reveal if there are structural differences at the nanocrystal surface which might explain the observed differences in the photoluminescence efficiency. Significant differences are indeed observed in high-resolution spectra of the Te 4d and Te 3d level. In contrast to the highly luminescent nanocrystals, the lowly luminescent particles present a large amount of Te surface sites. A structure model is proposed which allows explanation of the differences in the luminescence efficiency.