Colloidal CdSe Nanocrystals from Tri-n-Octylphosphine: Part I: Growth and Optical Properties from Polar and Non-Polar Solvents

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DOIResolve DOI: http://doi.org/10.1166/jnn.2005.122
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TypeArticle
Journal titleJournal of Nanoscience and Nanotechnology
Volume5
Issue4
Pages659668; # of pages: 10
SubjectCdse Nano-Particles; Photoluminescent Properties; Polar and Non-Polar Dispersions; Semi-Conductor Nano-Crystals; Solvent Sensitivity; Synthesis and Characterization
AbstractThis manuscript reports the ready synthesis of high-quality colloidal CdSe nanocrystals from tri-n-octylphosphine (TOP) and reports the optical properties of the resulting CdSe dispersed in non-polar and polar environments. With cadmium oxide (CdO) as the Cd precursor and TOPSe as the Se source, the CdSe nanocrystals were synthesized in a reaction medium consisting of TOP. The synthetic approach is as simple as: the swift injection of a TOPSe/TOP solution into a CdO/TOP solution at one particular (high) temperature, with subsequent growth at a lower temperature. The temporal evolution of the optical properties, including absorption and luminescence, were monitored in detail. The photoluminescence (PL) properties of the TOP-capped CdSe investigated comprise the intensity, emission peak wavelength, full width at half maximum of the PL spectra, and stability; these PL properties are sensitive to the history of growth as well as the environment of dispersion. An appropriate parameter, termed "Sensitivity Index (SI)," is proposed to define the percent difference in the PL intensity that arises when the dots are dispersed in non-polar hexane (Hex) as compared to polar tetrahydrofuran (THF). The decrease in the PL efficiency on going from Hex to THF is attributed to changes in surface states rather than in the internal core as more ligands are removed in THF. Dilution experiments further confirm the suggestion of the ligand removal mechanism and provide a conceptual estimate of surface quality via the SI parameter. Due to a slow growth in size (the size of the nanocrystals is almost constant during early 20 min) and good PL stability (tested as PL changes after storage for days both in dispersed or solid states, as well as after UV-irradiation), we suggest that our synthetic approach is likely to be practical for large-scale CdSe nanocrystals with good PL stability.
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AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences; NRC Institute for Biological Sciences
Peer reviewedNo
NPARC number12338865
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Record identifier49f4715e-b453-4553-9358-2414ac6bb8ee
Record created2009-09-11
Record modified2016-05-09
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