Photoluminescence behaviors of single CdSe/ZnS/TOPO nanocrystals: Adsorption effects of water molecules onto nanocrystal surfaces
Photoluminescence behaviors of single CdSe/ZnS/TOPO nanocrystals: Adsorption effects of water molecules onto nanocrystal surfaces
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DOI：
10.1016/j.jlumin.2007.02.023
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发表时间：
2007-11-01
影响因子：
3.6
通讯作者：
Tani, Toshiro
中科院分区：
文献类型：
--
作者：
Oda, Masaru;Hasegawa, Atsushi;Tani, Toshiro
我们在这里报告的独特的修改的光致发光（PL）行为在单一的CdSe/ZnS/TOPO纳米晶体取决于他们的环境。在真空和湿氮气氛下，已经获得了来自单个纳米晶体的长时间PL强度的痕迹。虽然在两种环境中的所有纳米晶体都表现出PL闪烁行为，即PL强度的开-关闪烁，但像往常一样，湿氮气气氛中的一些纳米晶体显示出开事件持续时间的显著增加。至于闪烁关断事件的持续时间，目前与载流子捕获的偶然事件相关，载流子捕获发生在位于表面上或附近的陷阱位置处。我们提出了一个模型，其中吸附的水分子在陷阱网站上的光照射下，转换它们的表面，这最终减少了发生的捕获事件，由于他们的失活。这反过来又增加了PL的接通时间。除了闪烁轮廓的剧烈变化外，我们还发现在真空中的PL时间迹线中出现了一些波动行为，即PL强度的连续的低频波动，而在湿氮气氛中则完全消失。这些结果也描述了上述引入的陷阱网站的失活模型的基础上。(C)2007 Elsevier B. V.保留所有权利。
We report here the distinctive modifications of photoluminescence (PL) behaviors in single CdSe/ZnS/TOPO nanocrystals depending on their environments. Long-time traces of PL, intensity from single nanocrystals have been obtained in both vacuum and a wet nitrogen atmosphere. While all of the nanocrystals in both environments exhibit PL blinking behaviors, i.e. on-off intermittency of PL intensity, as usual, some of the nanocrystals in the wet nitrogen atmosphere show significant increase in duration time of on-events. As for the duration time of blinking off-events, it is for the moment associated with the occasional events of carrier capturing at trap sites on or near the nanocrystal surfaces. We propose a model in which adsorbed water molecules at the trap sites on the nanocrystal surfaces transform them under light irradiation, which eventually decreases the occurrence of the trapping events due to their inactivation. It in turn increases the PL on-times. In addition to the drastic modification of the blinking profile, we also found that in the PL time traces some kinds of undulated behaviors, i.e. continuous and rather low frequency fluctuation of PL intensity, appear during each on-event in vacuum while they disappear totally in the wet nitrogen atmosphere. These results are also described on the basis of the inactivation model of the trap sites introduced above. (C) 2007 Elsevier B.V. All rights reserved.