Sharma, S. N. and Sharma, H. and Singh, S. and Mehra, R. M. and Singh, G. and Shivaprasad, S. M. (2010) Single pot synthesis of composition tunable CdSe–ZnSe (core–shell) and ZnxCd1–xSe (ternary alloy) nanocrystals with high luminescence and stability. Materials Research Innovations , 14 (1). pp. 62-67. ISSN 1433-075X

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Abstract

In this work, a simple, effective and reproducible synthetic route (single pot approach) for the preparation of high quality core–shell CdSe–ZnSe quantum dots (QDs) without the use of any pyrophoric organometallic precursors is presented. Effective surface passivation of stoichiometric, monodispersed, small sized (?5 nm) CdSe nanocrystallites is achieved by overcoating them with a ZnSe shell using zinc acetate as a zinc source by single pot approach. The resulting core–shell nanocrystallites exhibit high quantum yield values (?11·33%), narrow linewidth of the photoluminescence (PL) band, stable surface bonds configuration and superior structural properties at lower Zn content (?10 at-%). With increasing Zn content (?20 at-%), a composition tunable emission across the visible spectrum has been demonstrated by a systematic blue shift in emission wavelength due to the formation of ternary ZnxCd1–xSe QDs with acceptable luminescence properties. Here, contribution to emission process from surface states of nanocrystallites increases with zinc content. The core–shell and ternary QDs formed by different routes are modelled, based on the observations of several complimentary techniques (XPS depth profiling, PL, UV-Vis absorbance and TEM/TED). The improved properties of core–shell CdSe–ZnSe QD with similar zinc content using single pot synthesis approach as compared to the corresponding samples obtained by double pot synthesis are due to better passivation effect rendered by thin ZnSe shell in the former as compared to the latter. Their strong luminescence, narrow emission bands and wide colour tunability make such QD structures attractive for various scientific and commercial applications.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Maney Publishing.
Uncontrolled Keywords:	CORE-SHELL; SINGLE POT SYNTHESIS; LUMINESCENCE; CDSE?ZNSE; STABILITY; TERNARY ALLOY
Subjects:	Materials Science
Divisions:	UNSPECIFIED
Depositing User:	Ms Neetu Chandra
Date Deposited:	09 Jul 2012 09:03
Last Modified:	09 Jul 2012 09:03
URI:	http://npl.csircentral.net/id/eprint/308

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