Probing the size- and environment-induced phase transformation in CdSe quantum dots

Ajay S. Karakoti, Shail Sanghavi, Ponnusamy Nachimuthu, Ping Yang, Suntharampillai Thevuthasan

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The structural and electronic properties of CdSe quantum dots were investigated by in situ micro X-ray diffraction, X-ray photoelectron spectroscopy, and UV-visible absorption and emission spectroscopy. The in situ microdiffraction data show that the CdSe quantum dots capped with trioctylphosphine oxide (TOPO) or hexadecylamine (HDA) in toluene exhibit predominantly wurtzite crystal structure, which undergoes a phase transformation to zinc blende crystal structure following drop-casting on Si. Furthermore, decreasing the size of the CdSe quantum dots enhances this phase transformation. The X-ray photoelectron spectra show a systematic increase in the core level binding energies of Cd 3d and Se 3d and the band gap with decreasing size of CdSe QDs exhibiting quantum confinement. In addition, the Cd/Se ratio increases as the size of the quantum dots decreases from 6.6 to 2.1 nm, thereby increasing Se vacancies that cause the phase transformation. Drop-casting CdSe quantum dots on Si alter the arrangement of capping ligands and facilitate significantly more phase transformation.

Original languageEnglish
Pages (from-to)2925-2929
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume2
Issue number22
DOIs
Publication statusPublished - 17 Nov 2011
Externally publishedYes

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Quantum Dots
Semiconductor quantum dots
Phase transitions
Casting
Crystal structure
Photoelectron Spectroscopy
Quantum confinement
Core levels
Emission spectroscopy
Toluene
Photoelectrons
Binding energy
Absorption spectroscopy
X-Ray Diffraction
Electronic properties
Vacancies
Zinc
Structural properties
Spectrum Analysis
Energy gap

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Karakoti, A. S., Sanghavi, S., Nachimuthu, P., Yang, P., & Thevuthasan, S. (2011). Probing the size- and environment-induced phase transformation in CdSe quantum dots. Journal of Physical Chemistry Letters, 2(22), 2925-2929. https://doi.org/10.1021/jz201243t

Probing the size- and environment-induced phase transformation in CdSe quantum dots. / Karakoti, Ajay S.; Sanghavi, Shail; Nachimuthu, Ponnusamy; Yang, Ping; Thevuthasan, Suntharampillai.

In: Journal of Physical Chemistry Letters, Vol. 2, No. 22, 17.11.2011, p. 2925-2929.

Research output: Contribution to journalArticle

Karakoti, AS, Sanghavi, S, Nachimuthu, P, Yang, P & Thevuthasan, S 2011, 'Probing the size- and environment-induced phase transformation in CdSe quantum dots', Journal of Physical Chemistry Letters, vol. 2, no. 22, pp. 2925-2929. https://doi.org/10.1021/jz201243t
Karakoti, Ajay S. ; Sanghavi, Shail ; Nachimuthu, Ponnusamy ; Yang, Ping ; Thevuthasan, Suntharampillai. / Probing the size- and environment-induced phase transformation in CdSe quantum dots. In: Journal of Physical Chemistry Letters. 2011 ; Vol. 2, No. 22. pp. 2925-2929.
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