The Synthesis of Core/Shell Quantum Dots - Semiconductor Quantum Dots: Organometallic and Inorganic Synthesis - page 157

d n 1 y 4 n g | 3

Figure 5.10 High-resolution TEM images of a PbTe/CdTe core/shell QD: (a) along
the (111) axis, (b) along the (110) axis. Reprinted with permission
from K. Lambert, B. De Geyter, I. Moreels and Z. Hens, Chem. Mater. ,
2009, 21, 778. Copyright 2009 American Chemical Society.

a maximum quantum yield of 12%. To make the Cu 2 S/CdS material more
stable, a ZnS shell could also be deposited, which induced a signi

cant



emission blue shi  , attributed to the Zn atoms di using into the CdS shell.

A signi cant factor regarding these core/shell materials is that no emission

was observed from just the Cu 2 S cores alone, and only trap emission was
observed from the uncapped CdS.
In this chapter, we have shown that core/shell systems can be used to make
highly useful, resilient materials. The bandgap engineering of semi-
conductor nanomaterials, which was reported in earlier chapters, can be
improved to a new level of complexity when the range of materials and their
associated band structures is considered. Core emission can be protected,
shi



.

ed and the charge carriers can be tuned to various parts of the particle by
choosing the core and shell materials and their dimensions. Complicated
structures can be grown that exhibit unusual and interesting optical prop-
erties, which have found application in light-emitting device, solar and
bioimaging technologies.



References
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