Size-Dependent Composition and Molar Extinction Coefficient of PbSe Semiconductor Nanocrystals
Size-Dependent Composition and Molar Extinction Coefficient of PbSe Semiconductor Nanocrystals
复制标题
PbSe 半导体纳米晶体的尺寸依赖性组成和摩尔消光系数
DOI：
10.1021/nn9001616
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发表时间：
2009-06-01
期刊：
影响因子：
17.1
通讯作者：
Yu, William W.
中科院分区：
文献类型：
--
作者：
Dai, Quanqin;Wang, Yingnan;Yu, William W.
采用原子吸收光谱法、紫外-可见-近红外光谱法和透射电子显微镜测定了PbSe半导体纳米晶的原子组成和摩尔消光系数。Pb/Se原子比被认为是与系统过量的Pb原子在PbSe的PbSe的体系的尺寸依赖。实验结果表明，单个PbSe晶体是由PbSe核和额外的Pb原子层组成的非化学计量比晶体。对于这些非化学计量比的PbSe半导体纳米晶体，我们提出了一种新的计算方法来计算不同尺寸颗粒中Pb和Se原子的总数。这一计算对精确确定消光系数起了关键作用，消光系数与尺寸密切相关，其指数近似为2.5。
Atomic compositions and molar extinction coefficients of PbSe semiconductor nanocrystals were determined by atomic absorption spectrometry, UV-vis-NIR spectrophotometry, and transmission electron microscopy. The Pb/Se atomic ratio was found to be size-dependent with a systematic excess of Pb atoms in the PbSe nanocrystal system. Experimental results indicated that the individual PbSe nanocrystal was nonstoichiometric, consisting of a PbSe core and an extra layer of Pb atoms. For these nonstoichiometric PbSe semiconductor nanocrystals, we proposed a new computational approach to calculate the total number of Pb and Se atoms in different sized particles. This calculation played a key role on the accurate determination of the strongly size-dependent extinction coefficient, which followed a power law with an exponent of similar to 2.5.