Res. Chem. Intermed.
, Vol. 34, No. 2–3, pp. 287–298 (2008)
Koninklijke Brill NV, Leiden, 2008.
Also available online - www.brill.nl/rci
New strategy for band-gap tuning in
and YAOYU FENG
School of Life Science and Technology, Tongji University, Shanghai 200092, P. R. China
Department of Chemistry, East China University of Science and Technology, Shanghai 200237,
P. R . C h i n a
Received 22 November 2006; accepted 20 January 2007
Abstract—In the last decade, the main efforts have focused on the preparation of different sized
binary II–VI group semiconductor nanocrystals to obtain different color-emitting luminescence.
However, the tuning of physical and chemical properties by changing the particle size could cause
problems in many applications, in particular if unstable small particles are used. Recent advances
have led to the exploration of tunable optical properties by changing their constituent stoichiometries
in ternary alloy nanocrystals. High-quality Zn
Se alloy nanocrystals have been successfully
prepared at high temperature by incorporating stoichiometric amounts of Zn and Se into pre-prepared
CdSe nanocrystals or embryonic CdSe nuclei. With increasing Zn content, a composition-tunable
emission across the whole visible spectrum has been demonstrated by a systematic blue-shift in
emission wavelength. High-quality alloy Zn
S nanocrystals have been obtained by the co-
nucleation and co-growth of the constituents through the reaction of a mixture of CdO- and ZnO-oleic
acid complexes with sulfur at elevated temperatures. The obtained Zn
S alloy nanocrystals
possess superior optical properties with photoluminescence quantum yields of 25–50%, especially
the extremely narrow emission spectral width (fwhm = 14 nm).
Keywords: Alloy nanocrystals; band-gap tuning; luminescence; semiconductor.
The successful synthesis of high-quality (narrow size distribution and luminescent
peak width, high stability and luminescent efﬁciency) colloidal luminescent semi-
conductor nanocrystals (quantum dots, QDs) has made QDs an attractive alternative
to organic molecules in application such as light-emitting devices (LEDs) [1– 4],
lasers [5, 6] and biological ﬂuorescence labeling [7–10]. QDs are becoming popu-
lar as replacements for ﬂuorescent dyes in biological ﬂuorescence imaging because
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