Blinking Statistics and Excitation-Dependent Luminescence Yield in Si and CdSe Nanocrystals

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• 作者：Benjamin Bruhn ; Fatjon Qejvanaj ; Ilya Sychugov ; Jan Linnros
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：January 30, 2014
• 年：2014
• 卷：118
• 期：4
• 页码：2202-2208
• 全文大小：431K
• ISSN：1932-7455

文摘

ON鈥揙FF intermittency or blinking is a phenomenon observed in single quantum emitters, which reduces their overall light emission. Even though it seems to be a fundamental property of quantum dots (QDs), substantial differences can be found in the blinking statistics of different nanocrystals. This work compares the blinking of numerous single, oxide-capped Si nanocrystals with that of CdSe/ZnS core鈥搒hell nanocrystals, measured under the same conditions in the same experimental system and over a broad range of excitation power densities. We find that ON- and OFF-times can be described by exponential statistics in Si QDs, as opposed to power-law statistics for the CdSe nanocrystals. The type of blinking (power-law or monoexponential) does not depend on excitation but seems to be an intrinsic property of the material system. Upon increasing excitation power, the duty cycle of Si quantum dots remains constant, whereas it decreases for CdSe nanocrystals, which is readily explained by blinking statistics. Both ON鈥揙FF and OFF鈥揙N transitions can be regarded as light-induced in Si/SiO₂ QDs, while the OFF鈥揙N transition in CdSe/ZnS nanocrystals is not stimulated by photons. The differences in blinking behavior in these systems will be discussed.