Title :

Size-dependent optical properties of colloidal PbS quantum dots

Author(s) :

Moreels, Iwan [Auteur]
Universiteit Gent = Ghent University = Université de Gand [UGENT]
Lambert, Karel [Auteur]
Universiteit Gent = Ghent University = Université de Gand [UGENT]
Smeets, Dries [Auteur]
de Muynck, David [Auteur]
Universiteit Gent = Ghent University = Université de Gand [UGENT]
Nollet, Tom [Auteur]
Universiteit Gent = Ghent University = Université de Gand [UGENT]
Martins, José [Auteur]
Vanhaecke, Frank [Auteur]
Universiteit Gent = Ghent University = Université de Gand [UGENT]
Vantomme, Andre [Auteur]
Delerue, Christophe [Auteur]
Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]
Allan, Guy [Auteur]
Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]
Hens, Zeger [Auteur]
Universiteit Gent = Ghent University = Université de Gand [UGENT]

Journal title :

ACS Nano

Pages :

3023-3030

Publisher :

American Chemical Society

Publication date :

2009

ISSN :

1936-0851

English keyword(s) :

semiconductor nanocrystals
lead chalcogenide
PbSe
molar extinction coefficient
oscillator strength
exciton lifetime

HAL domain(s) :

Sciences de l'ingénieur [physics]

English abstract : [en]

We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots), by combining the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. ...
Show more >We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots), by combining the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. At high energies, the molar extinction coefficient ε increases with the Qdot volume d3 and agrees with theoretical calculations using the Maxwell−Garnett effective medium theory and bulk values for the Qdot dielectric function. This demonstrates that quantum confinement has no influence on ε in this spectral range, and it provides an accurate method to calculate the Qdot concentration. Around the band gap, ε only increases with d1.3, and values are comparable to the ε of PbSe Qdots. The data are related to the oscillator strength fif of the band gap transition and results agree well with theoretical tight-binding calculations, predicting a linear dependence of fif on d. For both PbS and PbSe Qdots, the exciton lifetime τ is calculated from fif. We find values ranging between 1 and 3 μs, in agreement with experimental literature data from time-resolved luminescence spectroscopy. Our results provide a thorough general framework to calculate and understand the optical properties of suspended colloidal quantum dots. Most importantly, it highlights the significance of the local field factor in these systems.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Non spécifiée

Popular science :

Non

Collections :

• Institut d'Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520

Source :

Harvested from HAL