期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 134, 期 5, 页码 2539-2542出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja211547s
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资金
- MEST [NRF-2011-C1AAA001-2011-0030278]
- Acceleration Program [NRF-2011-0000301]
The third-order nonlinear optical (3NLO) activity of PbS quantum dots (QDs) encapsulated in zeolite Y has been expected to depend sensitively on the countercation of the zeolite host. However, ion exchange of the pristine countercation, H+, with other cations has not been possible because the framework decomposes and the QDs aggregate immediately when the PbS QD-incorporating zeolite Y with H+ as the countercation is exposed to the atmosphere. We now report that when H+ is transformed to NH4+, the framework of PbS QD-containing zeolite Y does not undergo decomposition and the PbS QDs do not undergo aggregation to form larger QDs during the aqueous ion exchange of NH4+ with alkali-metal ions (M-A(+) = Li, Na+, K+, Rb+). The 3NLO activity of the M-A(+)-exchanged PbS QD-incorporating zeolite Y film increases with increasing size of M-A(+). The stabilization of the surface-bound exciton by the electron-rich framework oxide and electron-poor cation is proposed to be responsible for the increase. This is the first example of a method for systematically increasing the 3NLO activity of QDs dispersed in a dielectric matrix by systematically changing its properties. These results will serve as a guideline for future research and also promote applications of QD-incorporating zeolites in various fields.
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