Characterization of the Dynamics of Photoluminescence Degradation in Aqueous CdTe/CdS Core-Shell Quantum Dots.

Autor: Pankiewicz CG; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. cgpanki@gmail.com.; DISSE - INCT de Nanodispositivos Semicondutores, Rio de Janeiro, Brazil. cgpanki@gmail.com., de Assis PL; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil., Filho PE; Departamento de Biofísica e Radiobiologia, Universidade Federal de Pernambuco, 50670-901, Recife, Pernambuco, Brazil., Chaves CR; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil., de Araújo EN; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.; INCT em Nanomateriais de Carbono, Belo Horizonte, Brazil., Paniago R; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil., Guimarães PS; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.; DISSE - INCT de Nanodispositivos Semicondutores, Rio de Janeiro, Brazil.
Jazyk: angličtina
Zdroj: Journal of fluorescence [J Fluoresc] 2015 Sep; Vol. 25 (5), pp. 1389-95. Date of Electronic Publication: 2015 Aug 06.
DOI: 10.1007/s10895-015-1629-7
Abstrakt: We investigate the effects of the excitation power on the photoluminescence spectra of aqueous CdTe/CdS core-shell quantum dots. We have focused our efforts on nanoparticles that are drop-cast on a silicon nitride substrate and dried out. Under such conditions, the emission intensity of these nanocrystals decreases exponentially and the emission center wavelength shifts with the time under laser excitation, displaying a behavior that depends on the excitation power. In the low-power regime a blueshift occurs, which we attribute to photo-oxidation of the quantum dot core. The blueshift can be suppressed by performing the measurements in a nitrogen atmosphere. Under high-power excitation the nanoparticles thermally expand and aggregate, and a transition to a redshift regime is then observed in the photoluminescence spectra. No spectral changes are observed for nanocrystals dispersed in the solvent. Our results show a procedure that can be used to determine the optimal conditions for the use of a given set of colloidal quantum dots as light emitters for photonic crystal optical cavities.
Databáze: MEDLINE
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