期刊
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
卷 13, 期 45, 页码 20255-20261出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c1cp21366k
关键词
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资金
- National Natural Science Foundation of China [50872123, 50802083, 51072054, 60908007]
- National Basic Research Program of China [2011CB808100]
We report the synthesis of silicon nanocrystals via a one-step route, namely, femtosecond laser ablation in 1-hexene under ambient conditions. The size of these silicon nanocrystals is 2.37 +/- 0.56 nm as determined by transmission electron microscopy. Fourier transform infrared spectra and X-ray photoelectron spectra indicate that the surface of the silicon nanocrystals is passivated by organic molecules and is also partially oxidized by O-2 and H2O dissolved in the solution. These silicon nanocrystals emit stable and bright blue photoluminescence. We suggest that the photoluminescence originates from the radiative recombination of electron-hole pairs through the oxide-related centers on the surface of the silicon nanocrystals. The decay rate of the oxide-related surface recombination can be comparable to that of the direct band gap transition. In the excitation and emission spectra, a vibrational structure with nearly constant spacings (0.18 eV) is observed. We propose that the strong electron-phonon coupling between excitons and the longitudinal optical (LO) phonons of the Si-C vibration is responsible for this vibrational structure. The fluctuations in the peak resolution, about +/- 0.01 eV, are ascribed to the size distribution and presence of Si-O vibrations. These silicon nanocrystals offer stable luminescence and are synthesized through a green and simple route. They may find important applications in many fields, such as bioimaging and environmental science.
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