The effects of chemisorption on the luminescence of CdSe quantum dots
The effects of chemisorption on the luminescence of CdSe quantum dots
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DOI：
10.1021/la051898e
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发表时间：
2006-03-28
期刊：
影响因子：
3.9
通讯作者：
Mulvaney, P
中科院分区：
文献类型：
--
作者：
Bullen, C;Mulvaney, P
我们报道了刘易斯碱和其他配体对CdSe量子点在几种溶剂中的辐射复合的影响。长链伯胺被认为是最有效的封端剂的非极性溶剂中的CdSe量子点。伯烷基胺比仲烷基胺和叔烷基胺优越上级。在极性较小的溶剂如己烷或氯仿中的化学吸附和解吸的动力学受温度控制并且服从朗缪尔等温线。硫醇吸附也服从朗缪尔等温线，和烷基硫醇迅速取代胺，导致发光淬灭。在更极性的溶剂中，例如甲苯，配体解吸，导致发光猝灭。提出了表面Cd空位作为非辐射复合中心的观点。刘易斯碱对QD的吸附将表面空位能量提高到接近导带边缘或高于导带边缘，并且消除了由表面空位捕获的电子。溶剂极性对发光有很强的影响，因为溶剂决定了配体吸附到QD表面的程度。
We report on the effects of Lewis bases and other ligands on radiative recombination in CdSe quantum dots (QDs) in several solvents. Long-chain primary amines are found to be the most efficacious capping agents for CdSe QDs in nonpolar solvents. Primary alkylamines are superior to secondary and tertiary alkylamines. The kinetics of chemisorption and desorption in less polar solvents, Such as hexane or chloroform, are temperature controlled and obey a Langmuir isotherm. Mercaptan adsorption also obeys a Langmuir isotherm, and alkylmercaptans rapidly displace amines, leading to luminescence quenching. In more polar solvents, such as toluene, ligands desorb, leading to luminescence quenching. It is proposed that surface Cd vacancies function as nonradiative recombination centers. The adsorption of a Lewis base to the QD raises the surface vacancy energy close to, or above, the conduction band edge and eliminates electron capture by the surface vacancies. Solvent polarity has a strong effect on luminescence since the solvent determines the extent of ligand adsorption to the QD surface.