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Synthesis and Characterization of CdSe/CdS Core-Shell and CdSe/CdS Composites

Published online by Cambridge University Press:  21 February 2011

M. Azad Malika ,
Paul O'Brien  and
N. Revaprasaduac
M. Azad Malika
Affiliation:
Department of Chemistry, Imperial College of Science, Technology and Medicine, Exhibition Road, London, W7 2AZ, UK
Paul O'Brien
Affiliation:
Manchester Materials Science Centre and Department of Chemistry, Manchester University, Oxford Rd, Manchester M13 9PL. E-mail:[email protected]
N. Revaprasaduac
Affiliation:
Department of Chemistry, Imperial College of Science, Technology and Medicine, Exhibition Road, London, W7 2AZ, UK Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa, 886., South Africa
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Abstract

Highly mono-dispersed CdSe/CdS core-shell and CdSe/CdS composites have been prepared by a novel route involving thermolysis in TOPO using Cd(Se2CNMe(nHex))2 and Cd(S2CNMe(nHex))2. The absorption band edge (652 nm, 1.90 eV) of the CdSe-CdS core-shell structure is red shifted (22 nm, 0.0 17 eV) as compared to the CdSe nanoparticles (630 nm, 1.96 eV) whereas the absorption spectrum of the CdSe-CdS composites shows the absorption band edge at (584 nm, 2.12 eV), blue shifted (46 nm, 0.037 eV) as expected. Photoluminescence (PL, λex = 400 nm) of both the core-shell (622 nm) and the composites (588 nm) show values close to band edge emission. A sharper emission maximum with a considerable increase of intensity is observed for core-shell structure as compared to that of CdSe whereas the composite showed a broader emission maximum. The TEM images of the CdSe/CdS core-shell nanoparticles show crystalline, spherical particles with the average size of 53 Å (±7 %), a increase of 8 Å than the average size of CdSe (45 Å) nanoparticles, with a narrow size distribution. The High Resolution Transmission Electron Microscopy (HRTEM) showed lattice spacing intermediate between those for CdSe and CdS as is observed by Selected Area Electron Diffraction (SAED) and X-ray patterns (hexagonal phase). As expected no interface can be observed by HRTEM between CdSe core and CdS shell. The TEM image of the CdSe-CdS composites show particles with an average size of 48.7 Å (±10%).

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 581: Symposium F – Nanophase & Nanocomposite Materials II , 1999 , 291
Copyright
Copyright © Materials Research Society 2000

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