期刊
JOURNAL OF NANOPARTICLE RESEARCH
卷 13, 期 3, 页码 1049-1061出版社
SPRINGER
DOI: 10.1007/s11051-010-0094-0
关键词
CdSeS NCs; Doped; Surface defect; Upconversion luminescence; Synthesis
资金
- Natural Scientific Foundation of China [10774034]
- Foundation from Educational Bureau [11531283]
- Natural Scientific Foundation of Heilongjiang Province [F201032]
- Heilaogjiang University [Hdtd2010-15]
Upconversion luminescence was obtained from CdSeS nanocrystals (NCs) under 800 nm femtosecond laser excitation. The structural and optical characteristics of the CdSeS NCs were investigated experimentally by use of UV-visible absorption spectroscopy, transmission electron microscopy, X-ray diffractometry, and time-resolved luminescence dynamics. Peak shift of luminescence in CdSeS NCs can be readily observed under different wavelength femtosecond excitation. The pump power dependence of the luminescence intensity and time-resolved decay revealed that one, two, and three-photon absorption occur. It was found that upconversion luminescence is composed of photoinduced trapping and a band-edge excitonic state, and two types of species are involved in the biexponential luminescence decay kinetics. With increasing Se-doped composition, luminescence lifetimes of CdSeS NCs with similar sizes become shorter. This is not consistent with the changes of undoped CdS NCs and is ascribed to impurity level increased doping in the energy gap, which is favorable for trapping luminescence. A simple energy level of doping NCs is used to interpret upconversion luminescence and the peak shift of steady-state emission.
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