Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange
Open Access
- 12 January 2011
- journal article
- Published by Springer Science and Business Media LLC in Nanoscale Research Letters
- Vol. 6 (1), 79
- https://doi.org/10.1186/1556-276x-6-79
Abstract
Resonant Raman study reveals the noticeable effect of the ligand exchange on the nanocrystal (NC) surface onto the phonon spectra of colloidal CdTe NC of different size and composition. The oleic acid ligand exchange for pyridine ones was found to change noticeably the position and width of the longitudinal optical (LO) phonon mode, as well as its intensity ratio to overtones. The broad shoulder above the LO peak frequency was enhanced and sharpened after pyridine treatment, as well as with decreasing NC size. The low-frequency mode around 100 cm-1 which is commonly related with the disorder-activated acoustical phonons appears in smaller NCs but is not enhanced after pyridine treatment. Surprisingly, the feature at low-frequency shoulder of the LO peak, commonly assigned to the surface optical phonon mode, was not sensitive to ligand exchange and concomitant close packing of the NCs. An increased structural disorder on the NC surface, strain and modified electron-phonon coupling is discussed as the possible reason of the observed changes in the phonon spectrum of ligand-exchanged CdTe NCs.PACS: 63.20.-e, 78.30.-j, 78.67.-n, 78.67.BfKeywords
This publication has 49 references indexed in Scilit:
- Hybrid photovoltaic cells with II–VI quantum dot sensitizers fabricated by layer-by-layer deposition of water-soluble componentsThin Solid Films, 2009
- Resonant Raman study of phonons in high-quality colloidal CdTe nanoparticlesApplied Physics Letters, 2009
- Water-soluble CdSe nanoparticles stabilised by dense-shell glycodendrimersNew Journal of Chemistry, 2009
- Ligand removal from soluble CdTe nanocrystals evidenced by time-resolved photoluminescence spectroscopyJournal of Physics D: Applied Physics, 2008
- Self‐Assembling Nanoparticles at Surfaces and InterfacesChemphyschem, 2008
- “Jelly Dots”: Synthesis and Cytotoxicity Studies of CdTe Quantum Dot–Gelatin NanocompositesSmall, 2007
- Light Harvesting and Carrier Transport in Core/Barrier/Shell Semiconductor NanocrystalsThe Journal of Physical Chemistry C, 2006
- Interdot interactions and band gap changes in CdSe nanocrystal arrays at elevated pressureJournal of Applied Physics, 2001
- Pressure Raman scattering of CdTe quantum dotsPhysical Review B, 1997
- Size effects on the phonon spectra of quantum dots in CdTe-doped glassesApplied Physics Letters, 1996